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LIGHTNING CONDUCTORS




  LONDON: PRINTED BY
  SPOTTISWOODE AND CO., NEW-STREET SQUARE
  AND PARLIAMENT STREET




[Illustration: MONUMENT TO GENERAL BAIRD ON THE SUMMIT OF TOMACHAISTLE
NEAR CRIEFF PERTHSHIRE. STRUCK BY LIGHTNING, MAY 28, 1878]




  LIGHTNING CONDUCTORS

  THEIR
  HISTORY, NATURE, AND MODE OF APPLICATION


  BY
  RICHARD ANDERSON, F.C.S. F.G.S.

  MEMBER OF THE SOCIETY OF TELEGRAPH ENGINEERS
  ASSOC. INST. C. E.


  _WITH NUMEROUS ILLUSTRATIONS_


  LONDON
  E. & F. N. SPON, 46 CHARING CROSS

  NEW YORK
  446 BROOME STREET
  1880




_PREFACE._


The want in England of a good practical work on Lightning Conductors,
accessible to both the professional and non-professional reader, has
long been a subject of remark. That there are English works bearing
more or less on Lightning Protection will be seen at once on reference
to the Bibliography contained in the Appendix, pp. 231–248. But it
will be found these books are either obsolete and out of print, or are
written in a purely popular style that conveys little or no ‘usable’
information whereby may be obtained a trustworthy account of the growth
and application of the LIGHTNING CONDUCTOR.

It is with a view of meeting this need that the present work has been
written. It contains not only a history of the various methods that
have been used to this end, but also a thoroughly practical exposition
of the systems employed by the best authorities in various countries.

To Architects, Clergymen, Municipal Officials, and all those in charge
of large and lofty buildings, it would be impossible to over-estimate
the importance of this subject. Year by year an enormous amount of
property is destroyed merely because the simplest precautions have not
been taken to guard churches and other large buildings from the effects
of thunder storms.

The Author of this work can at all events claim a large practical
acquaintance with its subject. He feels convinced that those concerned
in the preservation of buildings, whether they be houses, churches, or
public offices, need only to learn the simple methods that can be used
to render the action of lightning innocuous, in order to adopt them.

            R. A.

  NEW MALDEN, SURREY:
    _October 1879_.




_CONTENTS._


  CHAPTER                                                           PAGE

         LIST OF BOOKS REFERRED TO, OR CONSULTED, RELATING TO
             LIGHTNING CONDUCTORS                                     xi

     I.  ELECTRICITY AND LIGHTNING                                     1

    II.  DISCOVERY OF THE LIGHTNING CONDUCTOR                         17

   III.  EARLY EXPERIMENTS WITH LIGHTNING CONDUCTORS                  25

    IV.  GRADUAL SPREAD OF LIGHTNING CONDUCTORS IN EUROPE             34

     V.  METALS AS CONDUCTORS OF ELECTRICITY                          49

    VI.  CHARACTER OF LIGHTNING AND OF THUNDERSTORMS                  62

   VII.  INQUIRIES INTO LIGHTNING PROTECTION                          73

  VIII.  SIR WILLIAM SNOW HARRIS                                      85

    IX.  THE BEST MATERIAL FOR CONDUCTORS                            100

     X.  HÔTEL DE VILLE, BRUSSELS, AND WESTMINSTER PALACE            111

    XI.  WEATHERCOCKS                                                121

   XII.  LIGHTNING PROTECTION IN FRANCE AND AMERICA                  125

  XIII.  LIGHTNING PROTECTION IN ENGLAND                             140

   XIV.  ACCIDENTS AND FATALITIES FROM LIGHTNING                     169

    XV.  THE EARTH CONNECTION                                        198

   XVI.  INSPECTION OF LIGHTNING CONDUCTORS                          218


         APPENDIX                                                    231

         INDEX                                                       249




_LIST OF BOOKS_

REFERRED TO, OR CONSULTED, RELATING TO THE HISTORY, NATURE, AND MODE OF
APPLICATION OF

LIGHTNING CONDUCTORS.


  ACHARD (Fr. K.) Kurze Anleitung ländliche Gebäude vor
      Gewitterchäden sicher zu stellen. 8vo. Berlin, 1798.

  ARAGO (François). Meteorological Essays. Translated by Colonel
      Sabine; with an Introduction by Baron von Humboldt. 8vo.
      London, 1855.

  BARBERET (J.) Dissertation sur le Rapport qui existe entre les
      Phénomènes de Tonnerre et ceux de l’Electricité. 2 vols. 4to.
      Bordeaux, 1750.

  BEAUFORT (Dr. Antonin de). Notice sur les Paratonnerres. 8vo.
      Châteauroux, 1875.

  BECCARIA (C. B.) Lettere dell’ Elettricismo. 4to. Bologna, 1758.

  BECCARIA (Giambatista). A Treatise upon Artificial Electricity.
      Translated from the Italian. 8vo. London, 1776.

  BECQUEREL (Antoine C.) Traité de l’Electricité et du Magnétisme. 7
      vols. 8vo. Paris, 1834–40.

  BERGMAN (T.) Tal on möjeligheten at förexomma askans skadeliga
      werkningar. 4to. Stockholm, 1764.

  BIGOT (P.) Anweisung zur Anlegung, Construction und Veranschlagung
      der Blitzableiter. 8vo. Glogau, 1834.

  BODDE (M.) Grundzüge zur Theorie der Blitzableiter. 8vo. Münster,
      1804.

  BOECKMANN (N.) Ueber die Blitzableiter. 8vo. Karlsruhe, 1791.

  BREITINGER (D.) Instruction über Blitzableiter. 4to. Zürich, 1830.

  BUCHNER (Dr. Otto). Die Konstruction und Anlegung der
      Blitzableiter, mit einem Atlas. 2nd edition, 8vo. Weimar, 1876.

  CALLAUD (A.) Traité des Paratonnerres. 8vo. Paris, 1874.

  CAVALLO (Tiberius). A Complete Treatise on Electricity. 2 vols.
      8vo. London, 1786.

  DALIBARD (M.) Histoire abrégée de l’Electricité. 2 vols. 8vo.
      Paris, 1766.

  DAVY (Sir Humphrey). Elements of Chemical Philosophy. 8vo. London,
      1810.

  DEMPP (K. W.) Vollständiger Unterricht in der Technik der
      Blitzableitersetzung. 8vo. München, 1842.

  EBERHARD (Dr.) Vorschläge zur bequemeren und zicherern Anlegung der
      Pulvermagazine. 8vo. Halle, 1771.

  EISENLOHR (Dr. W.) Anleitung zur Ausführung und Visitation der
      Blitzableiter. 8vo. Karlsruhe, 1848.

  EITELWEIN (J. A.) Kurze Anleitung auf welche Art Blitzableiter an
      den Gebäuden anzulegen sind. 8vo. Berlin, 1802.

  FAIT (E. M.) Observations concerning Thunder and Electricity. 8vo.
      Edinburgh, 1794.

  FERGUSON (James). An Introduction to Electricity. 3rd edition, 8vo.
      London, 1778.

  FIGUIER (Louis). Les Merveilles de la Science. 4to. Paris, 1867.

  FONVIELLE (Wilfrid de). Eclairs et Tonnerres. 8vo. Paris, 1869.

  FONVIELLE (Wilfrid de). De l’Utilité des Paratonnerres. 8vo. Paris,
      1874.

  FRANKLIN (Benjamin). Experiments and Observations in Electricity,
      made at Philadelphia, in America. 8vo. London, 1751.

  FRANKLIN (Benjamin). Complete Works in Philosophy, Politics, and
      Morals. 3 vols. 8vo. London, 1806.

  FRANKLIN (William Temple). Memoirs of the Life and Writings of
      Benjamin Franklin. 4to. London, 1818.

  GAY-LUSSAC (F.) et POUILLET (Claude). Introduction sur les
      Paratonnerres, adoptée par l’Académie des Sciences. 8vo. Paris,
      1874.

  GRENET (E.) Construction de Paratonnerres. 8vo. Paris, 1873.

  GROSS (J. F.) Grundsätze der Blitzableitungskunst. 8vo. Leipzig,
      1796.

  GUERICKE (Otto von). Experimenta nova Magdeburgica. Folio.
      Amsterdam, 1672.

  GÜTLE (J. K.) Neue Erfahrungen über die beste Art Blitzableiter
      anzulegen. 8vo. Nürnberg, 1812.

  HARRIS (William Snow) On the Nature of Thunderstorms, and the Means
      of Protecting Buildings and Shipping against Lightning. 8vo.
      London, 1843.

  HARRIS (Sir William Snow). A Treatise on Frictional Electricity.
      Edited by Charles Tomlinson. 8vo. London, 1867.

  HELFENZRIEDER (J.) Verbesserung der Blitzableiter. 8vo. Eichstädt,
      1783.

  HEMMER (J. J.) Kurzer Begriff und Nutzen der Blitzableiter. 8vo.
      Mannheim, 1783.

  HEMMER (J. J.) Anleitung Wasserableiter an allen Gattungen vor
      Gebäuden auf die sicherste Art anzulegen. 8vo. Frankfurt, 1786.

  HENLEY (William). Experiments concerning the Different Efficacy
      of Pointed and Blunt Rocks in securing Buildings against the
      Stroke of Lightning. 8vo. London, 1774.

  HOLTZ (Dr. W.) Ueber die Theorie, die Anlage und die Prüfung der
      Blitzableiter. 8vo. Greifswald, 1878.

  IMHOF (M. von). Theoretisch-practische Anweisung zur Anlegung
      zweckmässiger Blitzableiter. 8vo. München, 1816.

  INGENHOUSZ (Dr. Johan). New Experiments and Observations concerning
      Various Subjects. 8vo. London, 1779.

  KLEIN (Hermann J.) Das Gewitter und die dasselbe begleitenden
      Erscheinungen. 8vo. Graz, 1871.

  KUHN (Carl). Handbuch der angewandten Elektricitätslehre. Part I.
      Ueber Blitzableiter. 8vo. Leipzig, 1866.

  LANDRIANI (M.) Dell’ Utilità di Conduttori elettrici. 4to. Milano,
      1785.

  LAPOSTOLLE (M.) Traité des Parafoudres et des Paragrêles. 8vo.
      Amiens, 1820.

  LENZ (Heinrich F. E.) Handbuch der Physik. 2 vols., 8vo.
      Petersburg, 1864.

  LICHTENBERG (G. Ch.) Neueste Geschichte der Blitzableiter. 8vo.
      Leipzig, 1803.

  LUTZ (F.) Unterricht vom Blitze und Wetterableitern. 8vo. Nürnberg,
      1783.

  MAFFEI (F. S.) Delle Formazione dei Fulmini. 4to. Verona, 1747.

  MAHON (Lord). Principles of Electricity. 4to. Elmsly, 1780.

  MARUM (M. van). Verhandeling over hat Electrizeeren. 8vo.
      Groningen, 1776.

  MELSENS (M.) Notes sur les Paratonnerres, in ‘Bulletins de
      l’Académie Royale de Belgique.’ 8vo. Bruxelles, 1874–78.

  MELSENS (M.) Des Paratonnerres. 4to. Bruxelles, 1877.

  MEURER (Heinrich). Abhandlung von dem Blitze und den
      Verwahrungsmitteln gegen denselben. 4to. Trier, 1791.

  MURRAY (N.) Treatise on Atmospheric Electricity, including
      Observations on Lightning Rods. 8vo. London, 1828.

  NEWALL (R. S.) Lightning Conductors: their use as protectors of
      buildings, and how to apply them. 8vo. London, 1876.

  NOAD (Henry M.) Lectures on Electricity. 8vo. London, 1849.

  NOAD (Henry M.) A Manual of Electricity. 8vo. London, 1855.

  NOLLET (Abbé J. A.) Leçons de Physique expérimentale. 6 vols. 12mo.
      Paris, 1743.

  NOLLET (Abbé J. A.) Recherches sur les Causes particulières des
      Phénomènes électriques. 8vo. Paris, 1749.

  OHM (Georg Simon). Bestimmung des Gesetzes nach welchem die Metalle
      die Contact-Electricität leiten. 8vo. Nürnberg, 1826.

  PARTON (James). Life and Times of Benjamin Franklin. 2 vols. 8vo.
      New York, 1864.

  PHIN (John). Plain Directions for the Construction of Lightning
      Rods. 8vo. New York, 1873.

  PLIENINGER (Dr. P.) Ueber die Blitzableiter. 8vo. Stuttgart, 1835.

  PONCELET (Abbé M.) La Nature dans la Formation du Tonnerre. 8vo.
      Paris, 1766.

  POUILLET (Claude S. M.) Eléments de Physique expérimentale et de
      Météorologie. 7th edition, 2 vols. 8vo. Paris, 1856.

  PRAIBSCH (Christian). Ueber Blitzableiter, deren Nutzbarkeit und
      Anlegung. 8vo. Zittau und Leipzig, 1830.

  PREECE (W. H.) On Lightning and Lightning Conductors, in ‘Journal
      of the Society of Telegraph Engineers.’ 8vo. London, 1873.

  PRIESTLEY (Dr. Joseph). The History and Present State of
      Electricity. 2 vols. 8vo. London, 1775.

  REIMARUS (J. A. H.) Vom Blitze. 8vo. Hamburg, 1778.

  REIMARUS (J. A. H.) Ausführliche Vorschriften zur Blitz-Ableitung
      an allerlei Gebäuden. 8vo. Hamburg, 1794.

  ROBERTS (M.) On Lightning Conductors, particularly as applied to
      Vessels. 2 vols. 8vo. London, 1837.

  ROWELL (G. A.) An Essay on the Cause of Rain and its Allied
      Phenomena. 8vo. Oxford, 1859.

  SAUSSURE (H. B. de). Manifeste, en exposition abrégée, de l’Utilité
      des Conducteurs électriques. 8vo. Genève, 1771.

  SIGAUD DE LA FOND (M.) Précis historique et expérimental des
      Phénomènes électriques. 2nd edition, 8vo. Paris, 1785.

  SINGER (George John). Elements of Electricity. 8vo. London, 1814.

  SPANG (Henry W.) A Practical Treatise on Lightning Protection. 8vo.
      Philadelphia, 1877.

  SPARKS (Jared). The Works of Benjamin Franklin; with Notes and a
      Life of the Author. 10 vols. 8vo. Boston, 1840.

  SPRAGUE (John F.) Electricity: its Theory, Sources, and
      Applications. 8vo. London, 1875.

  STRICKER (Dr. Wilhelm). Der Blitz und seine Wirkungen. 8vo. Berlin,
      1872.

  STURGEON (William). Lectures on Electricity. 8vo. London, 1842.

  TAVERNIER (A. de). Blitzableiter, genannt Anti-Jupiter. 8vo.
      Leipzig, 1833.

  TINAN (Barbier de). Mémoires sur les Conducteurs pour préserver les
      Edifices de la Foudre. 8vo. Strasbourg, 1779.

  TOALDO (Giuseppe). Della Maniera di defendere gli Edifizii dal
      Fulmine. 8vo. Firenze, 1770.

  TOALDO (Giuseppe). Dei Conduttori per preservare gli Edifizii da
      Fulmine. 4to. Venezia, 1778.

  TOMLINSON (Charles). The Thunderstorm. 8vo. London, 1859.

  TYNDALL (John). Notes on Electrical Phenomena. New edition, 8vo.
      London, 1876.

  VERATTI (J.) Dissertatione de Electricitati cœlesti. 8vo. Bologna,
      1755.

  WEBER (F. A.) Abhandlung von Gewitter und Gewitterableiter. 8vo.
      Zürich, 1792.

  WHARTON (W. L.) The Effect of a Lightning Stroke. 8vo. London, 1841.

  WILSON (Robert). Boiler and Factory Chimneys; with a chapter on
      Lightning Conductors. 8vo. London, 1877.

  WINCKLER (Prof. J. H.) Gedanken von den Eigenschaften, Wirkungen
      und Ursachen der Elektricität. 8vo. Leipzig, 1744.

  YELIN (J. C. von). Ueber die Blitzableiter aus
      Messingdrahtstricken. 8vo. München, 1824.




LIGHTNING CONDUCTORS:

THEIR

HISTORY, NATURE, AND MODE OF APPLICATION.




CHAPTER I.

ELECTRICITY AND LIGHTNING.


‘First let me talk with this philosopher: What is the cause of
thunder?’ asks Shakspeare in ‘King Lear’ but without giving a reply.
The ‘philosopher’ of Shakspeare’s days had no answer to make; nor
had any others long after. From the dawn of history till within
comparatively modern times, thunder and lightning were mysteries to the
human mind; nor did there exist so much as a surmise that there might
be any connection between them and the equally mysterious agent called
electricity. The latter force indeed revealed itself early to attentive
observers, though in forms very different from those known at the
present time. The Greeks found out that amber, or ‘electron,’ attracted
certain other bodies under friction, and named the force after it; and
the Romans were aware that the shocks discharged by the torpedo fish
were of electrical nature, and they used them for the cure of rheumatic
complaints in the reign of the Emperor Tiberius. Both Greeks and Romans
also observed the sparks emitted, under certain circumstances, from
clothing and from the fur of animals. But this represented the total
sum of knowledge about electricity for ages and ages.

It was not until the year 1600 that Dr. William Gilbert, physician
to Queen Elizabeth, made a great step forward by showing in his
celebrated work, ‘De magnete, magneticisque corporibus, et de magno
magnete tellure, physiologia nova,’ that the two classes of phenomena,
the magnetic and the electric, are emanations of a single fundamental
force pervading all nature. Dr. Gilbert further discovered that many
other substances besides amber possess the electric power, and that
this power is easily excited when the air is dry and cool, and with
difficulty when it is moist and warm. These discoveries caused great
commotion in the European learned world, yet produced no further result
for another half a century. In 1650, Otto von Guericke, burgomaster
of Magdeburg, the inventor of the air-pump, who had studied with
deep interest Dr. Gilbert’s book, succeeded in constructing a little
electrical machine, composed mainly of a ball of sulphur mounted
on a revolving axis. By the aid of this instrument, very rude in
construction, he produced powerful sparks and flashes of electric
light, and it helped him likewise to discover, first, that bodies
excited by friction communicate their electricity to other bodies
by mere contact, and, secondly, that there resides in electrified
substances the power of repulsion as well as that of attraction.

Those who followed in the wake of the ingenious burgomaster of
Magdeburg for the next ninety or hundred years, till towards the middle
of the eighteenth century, did very little towards adding to the
already acquired knowledge of electricity. Sir Isaac Newton constructed
an electrical machine of glass, very superior to that of Otto von
Guericke, with which he made some amusing experiments; but, strangely
enough, drew no conclusions from them, treating the mighty force under
his eyes as only a plaything. This was all the more singular as a
contemporary of the great philosopher, Francis Hauksbee, like him a
Fellow of the Royal Society, called attention, in a volume entitled
‘Physico-mechanical Experiments,’ published in 1709, to the great
similarity between the electric flash and lightning, hinting that the
two might possibly be offspring of the same mysterious force. Dr. Wall,
in 1708, said that the light and crackling of rubbed amber seemed in
some degree to represent thunder and lightning. Another member of the
Royal Society, Stephen Gray--the first man in England who made the
study of electricity the devotion of his life, but of whose career very
little is known beyond the fact that he was very poor, and a pensioner
of the Charterhouse--added numberless experiments to those previously
made, and was bold enough to declare, in 1720, six years before Sir
Isaac Newton’s death, that ‘electricity seems to be of the same nature
with thunder and lightning--if we may compare great things with small.’
For this audacity in ‘comparing things’ he was sharply taken to task by
all the scientific men of the age, and, as deserved, set down as a man
out of his senses.

Nothing more was done for the next twenty-five years to enlarge the
knowledge of the phenomena of electricity. It stood, in fact, on a
footing not very far advanced from what it had been two thousand
years before. The achievements mainly consisted in a great number
of entertaining experiments performed for the delectation of great
and little children. Various machines had been made for exciting
electricity, but they served only, or at least chiefly, for amusement,
allowing ladies to fire off a cannon by a touch of their delicate hand,
and bringing ladies and gentlemen together to behold the wonderful
spectacle of an infant’s hair being made to stand on end, the little
creature having been placed upon cakes of resin, and fastened to the
ceiling by silken cords. The whole was little more than a repetition,
on a greater scale and with improved means, of the ancient Greek
experiment of rubbing a piece of amber on the sleeve of a philosopher’s
coat.

The first great step towards a practical insight into the nature and
phenomena of electricity, hitherto a mere plaything, was made in
the year 1745 in the ancient Dutch city and university of Leyden.
Two professors of the high school, John Nicholas Allamand, a member
of the Royal Society of London, and Peter Van Musschenbroek, author
of a treatise entitled ‘Introductio ad philosophiam naturalem,’ had
been trying, like many other scientific men of the time, electrical
experiments, when the thought occurred to them that the real reason
why all the work of the same kind had as yet produced such slight
results was that the electrical force was absolutely unstable. It
slipped, so to speak, through their hands, before they could look at
it; it vanished ‘like a dream, leaving no substance behind.’ One body,
they knew, had the power of electrifying another, but only to let
the mysterious force pass on, like a current of water running down a
cataract. Could they but ‘bottle up’ electricity, what a grand gain
would this be to science! So thought the two professors of Leyden
university; and thought justly. They went on experimenting, with this
end in view, till at last so-called ‘accident,’ the mother of millions
of human inventions and discoveries, threw a brilliant light on the
dark road along which they were groping their way.

One day Professor Allamand and Van Musschenbroek, together with a pupil
named Cuneus--a sort of Wagner, it would seem, sitting at the feet
of Dr. Faust--were trying the effects of electricity on a small iron
cannon, suspended by silk threads, and connected by a wire with a glass
bottle half full of water, when whey were startled by an extraordinary
incident. Curious, like all students of occult sciences, young Cuneus
took it into his head to see what would happen if he held the prime
conductor of the electrical machine in one hand and the electrified
bottle of water in the other. Something wonderful happened, indeed,
causing profound amazement and terror to the three persons witnessing
it, most of all to the immediate experimenter, who sank down on the
floor, half dead with fright. Master Cuneus had received an electric
shock. It was the first electric shock ever administered by artificial
means to any human being.

Such was the origin of the long-famous ‘Leyden jar,’ or, as it was
originally called, ‘Leyden phial.’ The whole of the scientific world
of Europe was as much startled by the discovery that electricity
could be imprisoned, like Ariel in an oak-tree, as the two Leyden
professors and their pupil had been, and a perfect fury set in for more
experiments. A professor of the University of Leipzig, in Germany, Dr.
Winckler, started the excitement by submitting his body to frequent
powerful shocks, opening up, besides, a scientific discussion in which
he came forth as the champion of the proposition that the discovery
of the ‘Leyden phial’ was due, not to the professors in the Dutch
university, but to a German ecclesiastic, Ewald George von Kleist,
who made the experiments of Messrs. Allamand and Van Musschenbroek a
year before them. His own sensations in submitting to the force of
electric shocks, Professor Winckler described, doubtless with some
exaggeration, as being convulsed from head to toe, and the prey of
violent agitations, which threw his arms about, and made the blood rush
from his nose. Dr. Winckler did not venture upon many experiments; but
his spouse, undismayed by the arm-shaking and nose-bleeding of her
lord, and having the combined curiosity of a woman and a professor’s
wife, continued upon her own person the electric shocks. However,
she did not take many, nor did science gain by the sacrifice. When a
few graspings of the ‘Leyden phial’ had deprived her of the power to
walk, and, what was worse, to speak, she followed the example of her
bleeding husband, and took ‘cooling medicines.’ All these wonderful
facts were made widely known at the time, and created the most profound
interest. Professor Musschenbroek, of Leyden, added not a little to the
prevailing excitement by writing to his friend René Antoine de Réaumur,
inventor of the thermometer named after him, a long letter, given at
once to the public, in which he dwelt upon the terrible effects of the
mysterious agency which he had helped to call into being, and wound
up by declaring that he had become terrified by his own foster-child,
and that he would not submit to another electric shock ‘for the whole
kingdom of France.’

Experiments in electricity now became the prevailing mania. Louis XV.
of France set the fashion among crowned heads of having his soldiers
electrified, to see what benefit he, or they, would derive from it. On
the instigation of Abbé Nollet, considered a man of high scientific
attainments, and who made several important discoveries in electricity,
the King submitted, in his own presence, 180 of the tallest men of his
life-guards, fastened hand to hand by iron wires, to repeated charges
from a connected group of Leyden jars. The big fellows were not visibly
influenced by the electric shocks, experiencing not so much as the
historical nose-bleeding of Professor Winckler of Leipzig, still less
the dumbness of his worthy spouse. On the contrary, the wire-bound
royal guards, conscious of but very slight sensations from the electric
shocks, and feeling somewhat indignant at this, and of being made
scientific tools without at least getting a strong bump on the head,
spoke out strongly, declaring the whole matter to be an imposture.

Having failed to electrify his soldiers, Louis XV. tried his monks.
It struck his Most Christian Majesty that perhaps the human creatures
who had the honour of fighting for him were endowed by nature with
rather tough hides, and that the case might be different in regard
to the softer beings upon whom devolved the task of praying for him.
Accordingly, the King issued orders that all the monks of the grand
convent of the Carthusians at Paris, over 700 in number, should be
electrified by the same connected group of Leyden jars which had
been tried upon the company of life-guards. The result was entirely
different, and most gratifying to the King. The shock had no sooner
been given when the whole file of monks gave an instantaneous jump,
uttering a howl at the same time. There were some eye-witnesses of
the affair who asserted that the Carthusians jumped and howled even
before the shock had been given, on seeing some one approach the Leyden
jar; but this was officially denied. King Louis XV. was so delighted
with this result of his scientific investigations, that he proposed
to submit all the monks of all the monasteries of France successively
to the process of being electrified, so that it might be accurately
ascertained upon what religious orders and communities it took the
greatest effect. His Majesty likewise was pleased to suggest, that,
after all the monks had been electrified, the nuns might be tried in
their turn. But the proposal was vetoed at Rome. There came definite
orders from the Supreme Pontiff forbidding the contact of any more
persons in the service of the holy Catholic Church with the sinful
electric wire; and the Carthusians of Paris remained the last monks,
as they had been the first, brought to jump and howl at the touch of a
Leyden jar.

From France and the continent of Europe the mania for electrical
experiments spread into England. But here it was taken up in a
thoroughly practical spirit, worthy of the genius of the nation.
Instead of aiming merely at the production of wonderful phenomena,
made to create astonishment, a number of scientific gentlemen formed
themselves into a body for the express purpose of seeking to ascertain
the nature, effects, and conditions of the mysterious agent which had
obtained the name of electricity. At the head of this body of inquirers
was Dr. William Watson, a member of the Royal Society, indefatigable
in the pursuit of science, and with him worked Martin Folkes, then
president of the Society, Lord Charles Cavendish, Dr. Bevis, and other
distinguished men. They set themselves, first of all, to ascertain in
what manner electricity was communicated through the solid earth, as
well as through fluid bodies; and, secondly, to enter upon experiments
showing the amount of speed at which the force travelled. With the
first object before them, they made some curious trials in the month
of July 1747, which attracted all London. They hung a wire over the
Thames, close to Westminster Bridge, attaching the one end to a Leyden
jar, and giving the other to a man who held it in the left hand, while
he grasped with the right an iron rod, standing in the river. Facing
the latter, on the opposite side of the Thames, not far from the
operators with the ‘jar,’ was stationed another person, also grasping
an iron staff planted in the river. After the charge had been given,
it was found that the electricity, after travelling by the wire over
the river, had come back by the water, the person holding the iron
staff on the starting side not only experiencing a shock himself, but
several individuals touching him. Not content with this experiment,
showing the transmission of electricity, Dr. Watson and his friends
made another, on a larger scale, a week afterwards, on the New River,
at Stoke Newington, London. They spanned, by chains and wires, a
circuit embracing 800 feet by land and 2,000 by water, with the result
of finding that the water transmitted the electric force by itself, if
merely an iron staff was placed in it. But they also discovered at the
same time that moist land would carry the force, equally with water.
To ascertain the latter fact more distinctly, the investigators made
a third experiment at Highbury Barn, Islington, setting up some miles
of wire, separated partly by land and partly by water. The conduit
of the electric force throughout the whole distance was found to be
uninterrupted, which led Dr. Watson to proclaim his conviction that the
agent was far more abundant throughout nature than had been formerly
believed.

In order to ascertain the speed at which the electric force traversed
space, Dr. Watson and his friends next entered upon a series of
experiments at Shooter’s Hill, near London. They sent an electric
discharge a distance of four miles, observers being stationed at each
end, and a gun fired at the touch of the Leyden jar, when it was shown
conclusively that the movement of the electric force was instantaneous.
This was an important step in advance, in overthrowing all formerly
established conclusions as to the agency being produced by a succession
of waves, like sound, and as such, moving slowly through space.

The field for electrical experiments was now becoming gradually
more extensive, and a few more practical tests of Mr. Watson and his
coadjutors led the way to the greatest knowledge of the all-pervading
force that had yet been achieved, in the clear apprehension that
lightning was but a manifestation of electricity. The new experiments
were chiefly made with the so-called electrical tube, a glass rod, from
two and a half to three feet in length and about an inch in diameter.
It had been known for some time that the tube, when gently warmed, so
as to be perfectly dry, and rubbed with a silk handkerchief, exhibited
strong symptoms of electricity, to the extent of throwing off luminous
sparks, which obtained the name of ‘electric fire.’ Dr. Watson found,
to his surprise, that this electric fire was not general and always
obtainable, but conditional upon circumstances. Having rubbed a glass
tube while he was insulated by standing upon a cake of wax, he found
that no electricity could be drawn from him by another person who
touched any part of his body, but that the same person could obtain
sparks from the tube by putting his hand near it. Dr. Watson likewise
observed, in the same train of experiments, that if an electrical
machine, together with the person turning the handle, were suspended
by silk, electric fire was not apparent until he touched the floor
with one foot, when the fire appeared upon the conductor. Having made
a great number of trials of a like nature, Dr. Watson made known the
important conclusion derived from them, namely, that glass tubes and
all similar ‘electrifiers’ did not contain within themselves the subtle
agent known as electricity, but formed only its temporary place of
rest, as a sponge would that of water. Dr. Watson was near proclaiming
the fact that electricity resides everywhere throughout the universe;
but for a moment he only touched the fringe of it. The discovery of
this grand truth was left to later investigators.

One curious result of the experiments made by Dr. Watson and his
friends, and which they themselves probably did not expect, was the
breaking out of a sort of public frenzy for making like trials, but
after the most childish fashion. Everybody who had, or thought he had,
the least tincture of science in him, procured a long glass tube,
and went on rubbing it assiduously with his handkerchief, sitting in
dark rooms and cellars, so as to be better able to watch the first
appearance of the ‘electric fire.’ Ladies and gentlemen alike went on
rubbing, with desperate energy, as if the fate of the world depended on
their exertions. They sold ‘electrical tubes’ in pastry shops; every
draper praised his own handkerchiefs as the best for rubbing; and
lecturers upon electricity went about through the length and breadth
of the land, with glass rods in their hands, delivering wonderful
harangues, and trying to explain to gaping multitudes the mysteries of
nature as regards electricity. The lecturers even crossed the Atlantic
to America, visiting the chief towns, and preaching to large assemblies
in places--

        Where blind and naked ignorance
    Delivers brawling judgments, unabashed
    On all things, all day long.

If it was a ludicrous spectacle to see these wandering lecturers, with
their glass tubes and pocket-handkerchiefs, the movement nevertheless
produced, apparently quite by accident, a striking result. It occurred
through one of the peripatetic preachers of electric revelation
coming face to face with Benjamin Franklin, a printer established
at Philadelphia, when on a visit to his native town of Boston,
Massachusetts, North America.

There are, in the records of scientific discovery, few figures so
interesting, because so full of marked individualism, as that of
Benjamin Franklin. He was not a man of genius, in the accepted sense
of the word; nor was he even a man of high talents. But he was
nevertheless a decidedly great man, his greatness consisting in the
largest development of that undefined faculty known as common sense.
Benjamin Franklin was the very ideal of a ‘practical’ man, that is,
a man valuing thoughts only as leading to actions, and new ideas
only as the road to visible results. The success of his career in
life was but an illustration of his thoroughly practical character.
Born at Boston in January 1706, the son of a tallow-chandler and
soap-boiler, he was destined by his parents to follow the same trade,
but not relishing the melting pots, he got apprenticed to an elder
brother, a printer at Boston. Harsh treatment drove him away from
this place before the terms of his apprenticeship were over, and with
scarcely a penny in his pocket, and the experience of only seventeen
years in his brain, he made his way to Philadelphia. A year after,
when eighteen years of age, he was induced to sail for England, and
was fortunate enough to find employment as a compositor in a printing
office in London, but so poor as to be compelled to take a lodging
for eighteen-pence a week. However, his self-reliance never deserted
him; he managed to go unscathed through all the perils of poverty and
friendlessness in a great city, and after a few years went back to
Philadelphia, with a small stock of money and a wealth of experience.
He now set up as a master printer, and gradually, though by very slow
degrees and ceaseless toil, devoted to multifarious objects, rose into
prosperity. For upwards of twenty years, from 1728 to 1748, he was the
most energetic and active man of business in Philadelphia. He was not
only a printer, but an author, an editor of newspapers, a compiler of
almanacks, a publisher, a bookseller, a bookbinder, and a stationer.
He made lamp-black and ink; he dealt in rags; he sold soap and geese
feathers; also, as he frequently made known to his fellow-townsmen
in printed notices, he had always in stock ‘very good sack at six
shillings a gallon.’ To dispose of the numerous articles in his store
he invented the art of advertising, unknown before him at Philadelphia.
All the inquiring minds of the ‘Quaker City’ assembled regularly in the
shop of Benjamin Franklin, ‘the new printing office near the market,’
which came to form the centre of intelligence, and the source from
which all public movements went forth.

The reward for all this activity was that at the end of twenty years
Benjamin Franklin had accumulated a handsome fortune, his average
income amounting to over two thousand pounds sterling a year: then
considered a very large sum, and of probably three times the purchase
value it would possess at the present day. With increasing wealth,
the active printer, happy in all his family relations, thought
himself justified to seek a little occasional leisure, which he found
chiefly in visits to Boston, his native town. It was on one of these
visits, made in the summer of 1746, that he went with a friend to
a lecture-hall, scarcely knowing what was to be the intellectual
entertainment prepared for him. It proved a discourse, with
illustrative experiments, upon electricity, by a Dr. Spence, duly armed
with a three-feet glass rod and silk pocket-handkerchief. Benjamin
Franklin was not merely interested: he was startled. It was to him,
as he afterwards declared to one of his friends, the opening of a new
world.

Perhaps the subject which attracted so suddenly the attention of
Benjamin Franklin might have escaped it again, in the pursuit of his
many vocations, but for another accidental circumstance. It so happened
that, immediately after his return to Philadelphia, there came a parcel
of books from England, accompanied by a present in the shape of an
electrical tube. The sender of it was the London agent of the Library
Company of Philadelphia, Mr. Peter Collinson, a member of the Royal
Society, and as such sharing the general interest in the electrical
experiments of Dr. Watson. The tube, which was accompanied with full
directions for its use, was no sooner unpacked, than Franklin seized
it eagerly and began experimenting, at the same time inspiring the
most sanguine of his friends to follow his example. Glass tubes, made
similar to the one sent from London, were soon procured from a local
manufacturer, and then began a general rubbing. ‘I never before,’
Franklin wrote, early in 1747, ‘was engaged in any study that so
totally engrossed my attention and my time as this has lately done; for
what with making experiments when I can be alone, and repeating them to
my friends and acquaintances, who, from the novelty of the thing, come
continually in crowds to see them, I have, during some months past,
had little leisure for anything else.’ To the greater number of those
friends and acquaintances who came flocking in crowds to the shop of
the Philadelphia printer, the electric tube was, probably, only looked
upon as a new toy; but it was vastly different as regarded himself. His
keen practical eye seemed to discern at once that the manifestations of
the mysterious force on which he was experimenting contained the germ
of something that might be utilised by men, or brought into obedience
to the human will.

It is not very clear from the published correspondence of Franklin what
his earliest views on the subject were, but there are many indications
that he conceived for a while that the ‘electric fire’ might be
employed in arts and manufactures. In his usual humorous style he spoke
of these utilitarian aims of his in a letter to Mr. Peter Collinson,
written in the early summer of 1747: ‘Chagrined a little that we
have not been able to produce hitherto anything in the way of use to
mankind,’ he wrote, ‘and the hot weather coming on, when electrical
experiments are not so agreeable, it is proposed to put an end to them,
for this season, in a party of pleasure on the banks of the Schuylkill.
Spirits at this party are to be fired by a spark sent from side to
side through the river, without any other conductor than the water:
an experiment which we some time since performed, to the amazement of
many. Then a turkey is to be killed for our dinner by the electrical
shock, and roasted by the electrical jack, before a fire kindled by the
electrified bottle, when the healths of all the famous electricians in
England, Holland, France, and Germany are to be drunk in electrified
bumpers, under the discharge of guns from the electrical battery.’

The longer he experimented, the more fascinated grew Benjamin Franklin
with his study of the phenomena of electricity. In order to be able to
devote himself completely to his darling science, he sold his printing
and publishing business in the year 1748, and went to live in a suburb
of Philadelphia, not far from the banks of the Delaware. At the same
time he purchased a complete set of electrical apparatus, the best that
had yet been manufactured, which had been brought over from Europe by
the same Dr. Spence who had given him his first ideas about electricity
at Boston. With these more perfect means he now continued his
investigations, arriving before long at results that formed an epoch in
the history of electricity.

The results achieved were wholly of a practical kind. With that strong
common sense which formed the most marked feature of his character,
Benjamin Franklin, at a very early period of his experiments, came
to the conclusion that of the actual _nature_ of electricity we know
nothing, and, in all probability, never can know anything, with our
finite senses. But, never losing sight of this starting point, he
treated electricity as astronomers do the movement of the heavenly
bodies. Of the incomprehensible forces that keep countless worlds in
their courses through measureless space, astronomers know no more than
the most ignorant of mankind; still they are able to arrive at very
accurate calculations concerning the directions followed by stars and
planets, and the amount of time consumed in their wanderings through
the inconceivable universe. To such astronomical endeavours Franklin
limited all his researches, and it was precisely because he so limited
them that he achieved greater successes than any other investigator of
the phenomena of electricity.

Together with many smaller matters, Benjamin Franklin added three great
discoveries to the knowledge of electricity. The first was that the
electric fluid--so called for want of a better word to express the
action of the mysterious force--will run its course more easily and
quickly through sharply pointed metals than in any other way. This had
never before been demonstrated, nor, probably, been ascertained. The
second great discovery of Franklin was that of positive and negative
electricity, or, as he called it for some time, _plus_ and _minus_,
the latter names being really the most descriptive. Of the actual
existence of these two divisions of the great and marvellous agency,
now attracting and now repelling each other, much was known previous
to Franklin, but he was the first to make them clearly understood,
and to bring their effects within reach of calculation. To these two
discoveries Benjamin Franklin added a third, the greatest of all. He
established the identity between the electric force and lightning,
and upon it based one of the noblest inventions of all ages, that of
the lightning conductor. And perhaps there never was any invention
acknowledged more deeply by mankind. The French Academy expressed it
when, on Franklin’s entrance, all the members rose, and the President
exclaimed ‘_Eripuit cœlo fulmen_.’

The identity of the electric force and lightning, vaguely surmised
by previous inquirers, and expressed at times in hints, was not only
firmly asserted by Benjamin Franklin, but at a comparatively early part
of his investigations proved by him in experiments. His broad practical
way of looking at facts succeeded in grasping a truth which all the
learned men before him, who had busied themselves with electrical
experiments, had not been able to lay hold of, simply because they lost
themselves in philosophical abstractions. The professors sought the
unattainable, and he confined himself strictly to what he considered
within reach, and it was thus he gained his end.

The thoroughly matter-of-fact way in which Franklin went to work
is strikingly exhibited in his own description as to how he came
to the conclusion of the oneness of lightning and electricity. In
reply to a friend and correspondent, living in South Carolina, who
had asked him how he came to such an ‘out-of-the-way idea’ as that
of the majestic fire from the cloud-capped firmament being exactly
the same with the puny gleam from a stick of glass, rubbed with the
sleeve of an old coat, Franklin wrote a highly characteristic letter.
‘I cannot answer your question better,’ he told his friend, ‘than
by giving you an extract from the minutes I used to keep of the
experiments I made. By this extract you will see that the thought was
not so much an out-of-the-way one but that it might have occurred to
any electrician. The extract, dated November 7, 1749--a date worth
remembrance in the history of scientific progress--was as follows
in its entirety:—‘Electrical fluid agrees with lightning, in these
particulars: 1. Giving light. 2. The colour of the light. 3. In the
crooked direction of the flame. 4. In the swift motion. 5. In being
conducted by metals. 6. In the crack, or noise, of the explosion. 7.
The subsisting in water, or ice. 8. In the rending of bodies it passes
through. 9. In destroying animals. 10. In melting metals. 11. In firing
inflammable substances. 12. The sulphurous smell. The electric fluid
is attracted by points, and we do not know whether this property is in
lightning. But since they agree in all the particulars wherein we can
already compare them, is it not probable that they agree likewise in
this? _Let the experiment be made._’




CHAPTER II.

DISCOVERY OF THE LIGHTNING CONDUCTOR.


With that liberality which distinguishes all truly great minds,
Benjamin Franklin did not keep his great discoveries to himself,
but communicated them to others in the most open-handed manner.
Ever since he had commenced his electrical experiments, he had sent
the detailed results of them to his London correspondent, Mr. Peter
Collinson, for communication to the Royal Society, and he was not
even prevented from continuing the labour of writing long letters by
the knowledge of the fact that scant notice was taken of them by the
Royal Society. The members of this august learned body, with a few
honourable exceptions, seemed unable to hide their contempt for what
they considered the dabblings in science of a mere tradesman, living
in an obscure little town, in a distant colony. Somebody had mentioned
in public that this person, of the name of Franklin, was a dealer in
rags and goose-feathers, dwelling among money-worshipping Quakers in
the City of Brotherly Love: which naturally was productive of great
merriment, but detrimental to scientific respect. Thus, although by the
influence of Mr. Collinson and some of his friends, the letters from
Philadelphia were read before the Royal Society, they met with scarcely
any attention, and the members broadly expressed their disdain of them
by refusing to allow their insertion in their ‘Transactions.’ Three
whole years elapsed in this way, when at length, in the autumn of 1750,
Benjamin Franklin reported to Mr. Collinson his researches on the
identity of electricity and lightning, together with his ideas that all
damage done by the electric fire descending from the clouds upon the
earth might be put a stop to by fixing iron rods, with sharp points, to
the summit of buildings, which would thus be protected. He added that
he himself intended shortly to verify his conclusions by experiments,
but that, in the meanwhile, it would be well if others did the same.
Never before, perhaps, was a grand idea thrown out to all the world
with more munificence of spirit, and with more entire abnegation of the
very thought of self.

Franklin’s letter made a great impression upon Mr. Collinson. Anxious
to make it public, while persuaded that the Royal Society would give no
better reception to it than to the author’s previous communications, he
hastened to Mr. Edward Cave, proprietor and editor of the ‘Gentleman’s
Magazine,’ and asked him to print it in his publication, the most
widely read at the time. A man of quick sense, Mr. Cave, too, saw at
once the vast importance of Franklin’s paper, describing his discovery,
and readily offered to print it, but recommended that it should be done
in pamphlet form, as likely to make the facts even more extensively
known than could be the case in his own Magazine. This having been
agreed to, there appeared, early in May 1751, a pamphlet with the
name of Benjamin Franklin on the front page, and a preface by Dr.
Fothergill, entitled, ‘New Experiments and Observations in Electricity,
made at Philadelphia, in America.’ It was the most important
contribution to science published since the appearance, five-and-thirty
years before, of Newton’s ‘Principia.’

Like Newton’s book, that of Franklin was not immediately successful--at
least not in England. Not appearing under the patronage of the Royal
Society, the supposed fountain-head of all legitimate science, it
was looked coldly upon by the public and the critics, and it was
only after having been greeted with immense applause in France, that
at last something like justice was done to it in England. The great
success of Franklin’s little treatise in France was due, in the first
instance, to rather accidental circumstances, but was none the less
genuine. By a happy chance a copy of the pamphlet printed by Mr. Cave
fell into the hands of the Count de Buffon, the greatest naturalist of
the age, and whose pre-eminent position was established not only in
France, but throughout the whole of Europe. Himself familiar with the
English language, he yet thought that it was necessary to have the book
immediately translated into French, and he employed for the purpose
Professor Dubourg, a literary man of note, well versed in electrical
science. Under such favourable auspices, Franklin’s pamphlet, carefully
translated, was issued at Paris in the summer of 1751, three or four
months after its appearance in London. Its success in France was as
immediate as it was great, and the wave of it spread at once over
Europe, marked by German, Italian, and Latin translations of the ‘New
Experiments.’ For a considerable time nothing was talked of among the
upper classes of France but the discoveries in science of the unknown
Philadelphia printer, and the king, Louis XV., following the fashion of
the day, ordered a course of the electrical experiments, described by
Franklin, to be performed before him at St. Germain, in the presence of
the whole court.

A rather ludicrous incident, and which gave rise to a great deal of
scientific tournamenting, added to the celebrity of Franklin’s little
book on the continent of Europe. The greatest of French electricians,
Abbé Nollet, a man of acknowledged merit, but inordinately vain,
was mystified in believing that the pamphlet which caused such an
immense stir at court and among the public was not the production
of the obscure man Franklin of Philadelphia, but got up among his
enemies in England and France, to rob him of his reputation. With this
belief fixed in his mind, he sat down at his desk to write a series
of letters intended to demolish the man of Philadelphia, and proving,
entirely to his own satisfaction, first, that Franklin did not exist
at all; secondly, that he had no right to exist; and thirdly, that
all his pretended discoveries were mere dreams. Not long after the
publication of his letters, the wrathful Abbé received undoubted proofs
from America that at Philadelphia there was a man called Franklin,
who himself mildly asserted his right not only to live, but to make
experiments in electricity. Poor Abbé Nollet felt his humiliation all
the more keenly as holding the post of preceptor in Natural Philosophy
to the royal family of France, and he had to suffer from a ‘burst of
inextinguishable laughter’ at one of his appearances at court.

If Count de Buffon did great service to electrical science by getting
Franklin’s pamphlet translated into French, he did still more by
instigating a series of experiments tending to verify the great theory
put forward in the pamphlet, that lightning could be drawn from the
clouds by means of pointed iron rods. By his prompting, several
gentlemen interested in scientific pursuits engaged upon trials to this
effect, among them two persons of note, M. Dalibard and M. de Lor.
The first-named had the good fortune to be successful, and thereby to
hand his name down to posterity. A wealthy man of science, M. Dalibard
was in the habit of living, during a part of the year, in a handsome
country house situated at Marly-la-Ville, about eighteen miles from
Paris, on the road to Pontoise. Marly-la-Ville stands on a high plain,
some four hundred feet above the sea-level, and the residence of M.
Dalibard being situated on the most elevated part of the ground, it
formed an excellent place for experiments, and was chosen as such by
Count de Buffon. The garden near the house was selected as the best
ground for the experiments. A wooden scaffolding was built up to hold
in its midst an iron rod, eighty feet long, and slightly over an inch
in diameter. On the top of the rod was fastened a piece of polished
steel, sharply pointed, and bronzed to prevent rust. The iron rod
entered, five feet from the ground, into another thinner one, running
horizontally towards an electrical apparatus, fastened to a table in
a kind of sentry-box, erected on purpose for observations. It was
M. Dalibard’s intention to make the experiments himself; but almost
immediately after the structure in his garden had been completed, he
was called by business to Paris, and left the whole in charge of one
of his servants, an old soldier, formerly in the French dragoons,
Coiffier by name. With true military spirit, Coiffier thought that
he ought to spend the greater part of his time in the sentry-box in
his master’s garden, and there he sat in the afternoon of Wednesday,
May 10, 1752, when a violent thunderstorm drifted over the plain
of Marly. Sufficiently instructed by his master what to do under
the circumstances, he touched the electrical apparatus with a key,
silk-bound at the handle, and to his extreme surprise, sees a flame
bursting forth. He touches another time, and there is a second flame
bursting forth, stronger than before. Then the old dragoon rushes from
his sentry-box--most famous private dragoon that ever lived, born to
the high honour of being the first man that ever drew lightning from
heaven.

It was not fear that drove the worthy servant of M. Dalibard from his
post, but a far better motive. He judged, with the prudence of an old
soldier, that the astounding things he had seen required witnesses,
in order that his master might not think him an inventor of fairy
tales. Accordingly, he hurried to the house of the prior of Marly,
M. Raulet, who lived close by, and asked him to behold the marvel of
marvels. The prior hesitated not for a moment to go, and, entering the
sentry-box, he also drew sparks from the electrical machine. Others of
the inhabitants of Marly-la-Ville, seeing the prior run, followed in
his wake, notwithstanding the rain was pouring down in streams, and
terror was struck among all of them in witnessing the dreaded lightning
creep down, serpent-like, but bereft of all its terrors, into the
sentry-box, in the centre of which stood the now exulting old dragoon.
As soon as the storm was over, the prior insisted upon Coiffier at
once saddling a horse, and riding full speed to Paris, to acquaint his
master with the great news that lightning had been drawn from the
skies by his apparatus at the blessed village of Marly-la-Ville. The
obedient dragoon did as advised, and three days after, on May 13, 1752,
M. Dalibard startled all the members of the Académie des Sciences of
Paris, convoked together in haste, by reading to them a full report of
what had taken place in the first great experiment for ascertaining the
truth of the suggestions of Benjamin Franklin.

All Europe soon rang with the report of the marvellous discovery
verified at Marly-la-Ville. But before the news of the experiment
made at the village near Paris had reached America, Benjamin Franklin
had made another, which, if not more conclusive, was at least more
original. Ever since he had arrived at his great conclusion regarding
the sameness of electricity and lightning, and the possibility of
conducting the latter to the ground harmlessly, by means of pointed
rods, the discerning citizen of Philadelphia had tried hard to find
some means for putting his ideas to a practical test, but met with
apparently insurmountable difficulties. His first plan was to set
up simply a tall iron rod near his house; but he abandoned this on
ascertaining, by measurement, that nearly all stormclouds passed over
Philadelphia, which was situated in a plain, at a height of several
hundred feet. In his then state of knowledge, he fancied that it
was impossible for him to reach the clouds in this manner. He next
resolved to await the building of an intended steeple for the principal
ecclesiastical edifice, and highest building of Philadelphia, Christ
Church. At that time not a steeple pierced the sky in all the extent
of the ‘Quaker city;’ nor was there a single one in the whole State
of Pennsylvania. But though Franklin made immense efforts to get the
steeple erected, starting a lottery for the purpose, and subscribing
largely to the funds, the work made little or no progress, many of the
principal inhabitants of the city being, from their religious opinions,
averse to the project. At last, getting impatient, Franklin’s ingenuity
hit upon the simplest of all means for verifying his great discovery.

One day he saw a boy flying a kite, and the thought instantly
occurred to him that here was the straight road from the earth to the
thunderclouds. Accordingly, he at once set to make a kite for his
intended experiments; but fearing he would incur the ridicule of his
sober fellow-citizens in engaging in what might seem to them a childish
undertaking, he kept the whole matter a profound secret. The kite he
made was not distinguished from those used by boys except of being made
of silk instead of paper so as to be able to stand the wet. Franklin
took an ordinary silk pocket-handkerchief, and fastened it over a cross
made of two light strips of cedar, by simply tying the four corners of
the handkerchief to the ends of the sticks. He next fastened a thin
iron wire, a foot long, to the top of the kite, and having provided it
with a loop and tail, attaching to the former a roll of twine, all was
ready for the experiment. Watching the skies diligently, he saw a dark
thundercloud coming up over Philadelphia late in the evening of July 4,
1752, and at once sallied forth from his house, situated at the corner
of Race and Eight streets, into a neighbouring field. There was nobody
with him but his eldest son, a lad of about twenty; and, in order to
get protection against the heavy downpour, as well as to hide from the
gaze of passers-by, the two sought shelter under an old cow-shed. Very
likely, had they been seen here at the time, the philosopher and son
might have been taken for two escaped lunatics, seeking so propitious
an occasion as a thunderstorm to fly their darling kite. Perhaps
Franklin too felt a little foolish, for he was about relinquishing his
experiment after several flashes of lightning which had not in the
least disturbed his kite, when a cloud darker than the previous one
came rolling up. All on a sudden, Franklin felt a smart shock, and saw
a spark flashing before his eyes. He had fastened the twine holding
his kite to a silk ribbon which he held in his hand, joining twine
and silk by a large key, attached to a Leyden jar. The latter at once
became heavily charged, and as shock followed upon shock, and flash
upon flash, there vanished all doubt from Franklin’s mind as to the
absolute truth of the grand discovery he had made. It may be imagined
with what inward satisfaction the great citizen of Philadelphia drew
in his kite, and crept out from under the cow-shed, when the storm was
over, and went home exultingly, the happiest of philosophers.

The experiment of Benjamin Franklin in drawing, as he thought, the
electricity of stormclouds to the ground by his kite, and thereby
demonstrating the necessity for the establishment of lightning
conductors, for the protection of persons and buildings, was accepted
as thoroughly satisfactory by the whole scientific world of Europe
at that time. Franklin was wrong, however, in supposing that the
lightning had really passed along his kite-string from the clouds to
the earth, for, had this been the case, he would undoubtedly have
been killed. What he witnessed was merely the inductive action of
the thundercloud on the kite and string. There had been some doubts
in respect to the experiment made, at the suggestion of Franklin’s
pamphlet, at Marly-la-Ville, since all the witnesses were inexperienced
persons, entirely unacquainted with the phenomena of electricity; but
there could be none whatever as regarded that tried by the originator
himself, and pronounced satisfactory by him. The fame of the wonderful
discovery spread with extraordinary swiftness through the civilized
world. Praises and congratulations flowed in upon the hitherto obscure
citizen of Philadelphia from all sides. The king of France sent him
a letter, full of compliments; the Royal Society of London voted him
their gold medal, modestly claiming a share in his work; and nearly
all the scientific bodies of France, Germany, and Italy elected him an
honorary member. But the praise of which Franklin had most reason to
be proud came from the great philosopher Immanuel Kant. The sage of
Königsberg grandly called him the modern Prometheus, bringing fire from
heaven.




CHAPTER III.

EARLY EXPERIMENTS WITH LIGHTNING CONDUCTORS.


The first actual lightning conductor ever constructed was set up by
Benjamin Franklin himself, at his house in Philadelphia. Its main
object was to protect the house against the effects of thunderstorms;
still experiments were so dear to the heart of the great discoverer,
that he could not help making trials even with things devoted to other
uses. It was in the summer of 1752 that Franklin erected over his house
a lightning conductor, made entirely of iron, but with a sharp steel
point on the top, the latter projecting seven or eight feet above the
roof, while the end was above five feet in the ground. Curious to know
whenever an electrical stream was passing through the conductor, he
attached to it an ingenious contrivance, by means of which through
an electric spark two bells were set in movement as soon as this
took place, the greater or lesser noise from them corresponding with
the strength of the electrical current. With the aid of this device
Franklin was enabled to observe some curious phenomena, which at first
puzzled him not a little. ‘I found the bells rang sometimes,’ he
informed a friend, ‘when there was no lightning or thunder, but only a
dark cloud over the rod; that sometimes, after a flash of lightning,
they would suddenly stop, and at other times, when they had not rung
before, they would, after a flash, suddenly begin to ring; that the
electricity was sometimes very faint, so that when a small spark was
obtained, another could not be got for some time after. At other
times, the sparks would follow extremely quickly; and once I had a
continual stream from bell to bell, the size of a crow-quill. Even
during the same gust there were considerable variations.’ By continued
watching, Franklin came to make the discovery that the fluctuations
in the electrical current were owing to changes and interchanges,
in atmosphere and earth, of positive and negative electricity. He
held at first that thunder-clouds are usually in a negative state of
electricity, but afterwards discovered that they varied from negative
to positive during the same storm.

Notwithstanding the unbounded praises bestowed upon Benjamin Franklin
for the great discovery of the lightning conductor, the actual
adaptation of it spread with extreme slowness. It was in the country
of its origin that it was brought into public use, all the countries
of Europe lagging far behind. But even in the Northern States of
America, though inhabited by a highly intelligent race, there were
great difficulties to overcome. The ministers of religion at first
seemed to think that the iron rods were not altogether free from the
suspicion of infidelity. Franklin himself had the reputation of being
a free-thinker, and indeed never hid from others the fact of his being
accustomed to examine all matters by the light of his own reason, and
to believe nothing that he could not understand. Perhaps on the same
ground many of the New England ministers did not believe in lightning
conductors. They could not understand them. A heavy shock of earthquake
was felt throughout Massachusetts in the summer of 1755, whereupon a
Boston clergyman instantly came forward, denouncing in eloquent strains
the erection of a number of lightning conductors which had taken place.
The high iron rods, he gravely maintained, had been the cause of the
earthquake, by drawing vast masses of electricity from the atmosphere
into the ground. A distinguished friend of Franklin, Professor
Winthrop, of Harvard College, thought it necessary to come forward and
defend lightning conductors against the accusation of accumulating
electricity, but without convincing the plaintiff. A different charge,
still more serious in the eyes of pious people, had been made against
lightning conductors some years before. Another Boston clergyman,
coming forward in 1770, opposed the use of Franklin’s iron rods on the
ground that, as the lightning was one of the acknowledged means of
punishing the sins of mankind, and of warning them from the commission
of acts of wickedness, it was impious ‘to prevent the execution of the
wrath of heaven.’ To this gentleman also Professor Winthrop deemed
it requisite to reply. Franklin himself remained silent, wrapping
himself in the mantle of the sage. But he allowed his friend Ebenezer
Kinnersley, of Philadelphia, who went travelling, by his wish and
partly at his cost, through the principal towns and villages of the New
England States, to explain to the people the uses and advantages of
lightning conductors, to preface all his lectures by the announcement
that the erection of iron rods to protect houses from the effects
of thunderstorms was not an act ‘chargeable with presumption, nor
inconsistent with any of the principles either of natural or revealed
religion.’

In the gradual spread of lightning conductors through the British
colonies of North America, Franklin himself took the leading part. He
employed all his leisure time, engrossed though it was more and more
by political affairs, in which he was destined to take a world-famous
part, in going from one part of the country to another, advocating the
use of conductors, advising as to the best mode of their construction,
and, whenever he could, examining into the effects of strokes of
lightning upon buildings. How minute he was in these inspections, and
how practical in the conclusions he almost invariably drew from them,
Franklin gives proof in one of his letters addressed to his friend
Collinson in London. He tells him that he inspected the church of
Newbury, in Massachusetts, which had been struck by lightning, and
traced, foot by foot and inch by inch, the road which the electric
current had taken, creating great havoc and destruction. ‘The steeple,’
he says, ‘was a square tower of wood, reaching seventy feet up from
the ground to the place where the bell hung, over which rose a taper
spire, of wood likewise, reaching seventy feet higher, to the vane
of the weathercock. Near the bell was fixed an iron hammer to strike
the hours; and from the tail of the hammer a wire went down through a
small gimlet-hole in the floor the bell stood upon; then horizontally
under and near the plastered ceiling of that second floor, till it came
to a wall; and then down by the side of this wall to a clock which
stood about twenty feet below the bell. The wire was not bigger than
a common knitting-needle.’ It surprised Franklin that ‘the lightning
passed between the hammer and the clock in this wire, without hurting
either of the floors, or having any effect upon them, except making
the gimlet-holes, through which the wire passed, a little bigger, and
without hurting the wall or any part of the building.’ The inference he
drew from this was, that even a comparatively thin mass of metal would
give passage to a powerful electric stream. ‘The quantity of lightning
that passed through the steeple,’ he informed his correspondent, ‘must
have been very great, as shown by its effects on the lofty spire above
the bell, and on the square tower below the end of the clock pendulum;
and yet, great as this quantity was, it was conducted by a small wire
and a clock pendulum, without the least damage to the building as far
as they extended.’

Besides travelling and employing lecturers, to make the advantages of
lightning conductors known, Franklin found means of doing so in an
annual publication he had started in the year 1732, known as ‘Poor
Richard.’ This almanac, humorous in form but very serious in substance,
which had acquired an enormous circulation, proved in the end the most
powerful instrument for spreading information on the great subject
dear, above all others, to Franklin’s heart, and leading his countrymen
to adopt, before all other nations, the wonderful metal rod, protective
against ‘the wrath of heaven.’ In several of the editions of the
almanac, notably the ‘Poor Richard’ for the year 1758, Franklin drew
attention to his lightning conductors in simple advertisements, drawn
up in a spirit of absolutely touching modesty and self-abnegation.
Not seeking the slightest reward for himself, nor even mentioning his
name, he only sought to benefit others by instructing them how to get
protection against the dangers of lightning. ‘It has pleased God,’
ran the advertisement in the almanac, ‘in His goodness to mankind, at
length to discover to them the means of securing their habitations and
other buildings from mischief by thunder and lightning. The method is
this:--Provide a small iron rod, which may be made of the rod-iron used
by nailers, but of such a length that, one end being three or four
feet in the moist ground, the other may be six or eight feet above the
highest part of the building. To the upper end of the rod fasten about
a foot of brass wire, the size of a common knitting-needle, sharpened
to a fine point; the rod may be secured on the house by a few small
staples. If the house or barn be long, there may be a rod and point at
each end, and a middling wire along the ridge from one to the other.
A house thus furnished will not be damaged by lightning, it being
attracted by the points and passing through the metal into the ground
without hurting anything. Vessels also, having a sharp-pointed rod
fixed on the top of their masts, with a wire from the foot of the rod
reaching down round one of the shrouds to the water, will not be hurt
by lightning.’ Franklin had occasion subsequently greatly to modify the
advice here given. He early discovered his error of lightning being
‘attracted by the points;’ and also found that his recommendation to
people to construct their own lightning conductors only led to grievous
calamities. There came reports from all sides of houses having been
severely damaged by lightning notwithstanding having conductors, and
close investigation soon showed that in every instance the apparatus
was defective, having been erected by unskilful hands, either the
owners themselves, or a set of wandering impostors, who soon made
themselves notorious as ‘lightning-rod men.’

Having improved in various ways the lightning conductor set up
experimentally over his own house, Franklin erected a second one, of
larger dimensions, to protect the residence of one of his friends, Mr.
West, a wealthy merchant of Philadelphia. The apparatus, constructed
entirely under the supervision of Franklin, consisted of an iron rod
half an inch in diameter throughout its length, and ending at the
bottom in a thick iron stake, driven four or five feet into the ground.
The top of the conductor, rising nine feet above the central stack of
chimneys, was formed by a brass wire ten inches in length, tapering off
in a sharp point. Franklin considered the brass wire, which was screwed
and soldered inside the iron rod, a great improvement upon simple iron,
having discovered brass, as well as copper, to be better conductors of
electricity. The result justified his expectations. Not many months
after the lightning conductor had been erected over the mansion of Mr.
West, a thunderstorm more severe than had been experienced for many
years broke over Philadelphia. Vivid flashes of lightning followed each
other incessantly, one of them striking, visible to all beholders, the
house of Mr. West, touching the point of the conductor on the roof,
and appearing again on its base in a thin sheet of flame. Naturally,
Franklin was delighted at this first notable result of his grand
discovery, and lost no time in examining the traces of the lightning
over his conductor. He found that the sharp metal point at the upper
end had been melted, and the small brass wire reduced from ten to seven
and a half inches, with its top very blunt. The thinnest part of the
wire, he saw at once, had disappeared in smoke, while the portion below
it, a little thicker, had simply been liquefied, sinking down while in
a fluid state, and forming a rough irregular cap, lower on one side
than on the other. This was a highly interesting test, showing that
the wire on the summit of the conductor must not be made too thin, so
as to be liable to be burnt. But still more interesting to Franklin
was the investigation of the report, confirmed on all sides, that a
sheet of flame had been seen at the base of the conductor, where it
was connected with the earth. He at once suspected that the earth at
the point, and down to the end of the metal rod, had been very dry,
and such indeed was the case. Hence he arrived at the conclusion that
all conductors should go deep enough into the earth to find sufficient
moisture quickly to dissipate the electric fluid. All subsequent
experience, down to the present day, has proved that the inference of
the practical philosopher of Philadelphia was as sound in this respect
as in the rest of his ever clear and lucid judgments.

Like most other inventions and discoveries, that of the lightning
conductor was destined not to be without its early martyrs. Among the
many searchers in the science of electricity on the continent of Europe
who had eagerly seized the ideas of Benjamin Franklin, and entered
enthusiastically upon the experiments recommended by him, was Professor
George Wilhelm Richmann, of St. Petersburg. He had conceived some
theories of his own regarding electrical discharges, and constructed
for experimental purposes an apparatus which he called the ‘gnomon,’
one of the uses of which was to measure the comparative strength of
electrical currents. The instrument consisted of a tube of metal,
terminating in a small glass vessel, into which, for some unknown
reason, he put a quantity of brass filings. Attached to the tube of
metal, at its top, was a chain, so arranged as to be easily attached
or detached from it, and this was fastened to an iron rod going to the
roof, in the form of a lightning conductor, as prescribed by Franklin.
It seems to have been the notion of the professor that he might lead
the electrical current from the clouds down into his ‘gnomon’ bottle,
there to measure its strength; though it is difficult to conceive
how a man acquainted with the manifestations of the mystic force
with which he was experimenting, and knowing its powerful effects,
should not have perceived the extreme danger of thus leading it into a
nonconducting element. However, the enthusiastic man, evidently blind
to all consequences, set out on his course of experiments. A violent
thunderstorm coming over St. Petersburg on August 6, 1753, Professor
Richmann hurried to his ‘gnomon,’ attached the chain to the phial, and
then stood to watch the effect, with not more than a foot and a half
distance between his head and the glass tube. Near him, but further
behind, stood a friend, M. Solokow, who was going to make a drawing
of the electrical apparatus. All on a sudden, there came a terrible
flash of lightning, described as ‘a ball of fire’ by M. Solokow, down
from the skies, falling upon the ‘gnomon’ and springing from thence
upon Professor Richmann, laid the latter dead on the floor, and his
companion senseless.

When the body of the unfortunate professor came to be examined, it was
found that the electric current had passed right through him, entering
at the forehead, and coming out at the sole of the left foot, both
places being distinctly marked by red spots and small perforations,
like those of a needle. There were no other marks of injury visible,
either inwardly or outwardly, except a number of red and blue spots
over the back and shoulders, which grew larger the day after, and
seemed to bring with them symptoms of rapid decay. Some of the medical
men attending the ‘post mortem’ examination were most desirous to
enter into further observations, so as to ascertain, if possible, the
actual cause which produced death by a stroke of lightning, but they
had no opportunity. When they returned to the professor’s house, the
second day after his death, the body was already so far decomposed as
to be unrecognisable, and it was with difficulty that the remains of
the first martyr of applied electricity could be got into a coffin and
carried to their last resting-place.

The appalling death of Professor Richmann produced an enormous
commotion, far beyond what might be expected from a similar event,
throughout the learned world of Europe. In France especially the
occurrence created the deepest impression, mingled with admiration of
what was called the ‘glorious death’ of the St. Petersburg professor,
and more than one student of electrical science boldly declared
his determination to become a martyr in the same noble cause. But
reflection, probably, brought better counsel, for, as it happened,
there were no more contributions, for the time being, to the roll of
martyrs.

[Illustration]




CHAPTER IV.

GRADUAL SPREAD OF LIGHTNING CONDUCTORS IN EUROPE.


In singular contrast with the burst of applause with which the whole
scientific world of Europe received the great discovery of Benjamin
Franklin, was the extreme slowness of the actual introduction
into Europe of lightning conductors. The opposition they met
with in Franklin’s own country was trifling to that which they
encountered in the principal states of Europe, more particularly
in England and France. It was natural, perhaps, that the lower
classes--ultra-conservative, through the mere effect of ignorance, in
every country in the world--should see danger in the setting-up of
iron rods which, as they were told, drew lightning from the skies;
and it was, perhaps, equally natural that religious fanatics should
regard them with extreme suspicion, as removing one of their imagined
instruments of heaven for punishing sinful mortals. Both these classes,
the untaught multitude and the bigoted zealots, opposed in Europe,
as they did in America, the establishment of lightning conductors;
but to the strength of these parties was unexpectedly added a third
in a not numerous but powerful section of learned literary men. They
were chiefly French, but had many adherents in England, as well as in
Germany, the _savants_ of both countries looking then upon France as
the seat of all science, and indeed human knowledge.

The opposition raised against lightning conductors in France was
entirely personal, its origin being due to the wounded vanity of a
very estimable but likewise a very weak man, the already mentioned
Abbé Nollet. Born in 1700, the Abbé had very early in life gained
renown for his scientific researches, and after a while devoted much
of his time to electrical experiments, in conjunction with two other
celebrated men, Dufay and De Réaumur. When the report of Franklin’s
discoveries arrived in Europe, the Abbé Nollet was generally looked
upon as the greatest of living ‘electricians,’ and the general homage
paid to him having roused his self-esteem to an inordinate degree, he
got fiercely irritated that another man, a previously quite unknown
person, in a distant land, should have dared to snatch from him his
scientific laurels. Accordingly, he used all his influence among the
public, in the scientific world, and at the French court, where he held
a high position as tutor of the King’s children, not only to depreciate
Franklin’s lightning conductors, but to set them down as something like
an imposture. In various treatises and articles published in learned
papers, Abbé Nollet sought to prove that the person called Benjamin
Franklin--in whose very existence he formerly refused to believe, but
which he now grudgingly acknowledged--was an individual unacquainted
even with the first principles of the science of electricity, and that
his proposal for protecting houses against lightning was so absurd
as not to be worth engaging the attention of any thinking man. More
than this, he argued that the proposed lightning conductors were not
only inefficacious, but positively dangerous. By thus joining in the
vulgar cry of lightning being, so to speak, sucked from the clouds
by Franklin’s conductors, the learned Abbé had the satisfaction of
retarding their introduction in his own, as well as other European
countries, for a number of years.

In France itself the thus awakened resistance to the setting-up of
lightning conductors was strikingly shown by an incident which occurred
at the town of St. Omer, not far from Calais. A manufacturer settled
here, who had been in America, and there learnt to appreciate the
usefulness of Franklin’s lightning conductors, had one made for his
own house, and quietly fixed it to wall and roof. But the populace no
sooner heard of it when there arose a public disturbance, and the iron
rod was torn down by force. So far from repressing the rioters, the
municipality of St. Omer, acting under priestly influence, forbade the
manufacturer to erect another lightning conductor, on the ground that
it was ‘against law and religion.’ Thereupon the bold manufacturer, a
man of English descent, to try his right, appealed to the tribunals,
and the judges at last, after protracted pleadings, not being able to
discover any statutes against the fastening of metal rods to buildings,
declared that the thing might be done, but with precautions. The lawyer
who pleaded the case of the lightning conductors before the French
tribunals at this momentous period was a very young man, quite unknown
to fame at the time, but destined for a superabundance of it. His name
was Robespierre.

Perhaps the violent opposition which the erection of lightning
conductors--or ‘Franklin rods,’ as they were often called--met almost
everywhere, would have proved more effective than it ultimately turned
out, had not the great discoverer himself showed admirable temper in
meeting his enemies, thus pouring oil upon the stormy waters. His
calmness and confidence is admirably shown in a letter, dated July 2,
1768, addressed to Professor John Winthrop, of Cambridge, in answer to
one in which astonishment was expressed at the ‘force of prejudice,
even in an age of so much knowledge and free inquiry,’ of not placing
lightning conductors upon all elevated buildings. Franklin--or he must
now be called Dr. Franklin, having received the degrees of LL. D.
and D. C. L. from the universities of St. Andrew’s, Edinburgh, and
Oxford--was residing in England at the time, as agent of the people of
Pennsylvania. He was thoroughly acquainted with the state of public
feeling, yet so far from being angry, smiled down upon it like a
true philosopher. ‘It is perhaps not so extraordinary,’ he wrote to
his friend, ‘that unlearned men, such as commonly compose our church
vestries, should not yet be acquainted with, and sensible of, the
benefits of metal conductors in averting the stroke of lightning, and
preserving our houses from its violent effects, or that they should
still be prejudiced against the use of such conductors, when we see
how long even philosophers, men of science and of great ingenuity, can
hold out against the evidence of new knowledge that does not square
with their preconceptions; and how long men can retain a practice that
is conformable to their prejudices, and expect a benefit from such
practice, though constant experience shows its inutility. A late piece
of the Abbé Nollet, printed last year in the Memoirs of the French
Academy of Sciences, affords strong instances of this; for though
the very relations he gives of the effects of lightning in several
churches and other buildings show clearly that it was conducted from
one part to another by wires, gildings, and other pieces of metal
that were _within_, or connected with the building, yet in the same
paper he objects to the providing of metallic conductors _without_ the
building, as useless or dangerous. He cautions people not to ring the
church bells during a thunderstorm, lest the lightning, in its way to
the earth, should be conducted down to them by the bell ropes, which
are but bad conductors; and yet he is against fixing metal rods on the
outside of the steeple, which are known to be much better conductors,
and through which lightning would certainly choose to pass, rather than
through dry hemp. And though, for a thousand years past, church bells
have been solemnly consecrated by the Romish Church, in expectation
that the sound of such blessed bells would drive away thunderstorms,
and secure buildings from the stroke of lightning; and, during so long
a period, it has not been found by experience, that places within
the reach of such blessed sound are safer than others where it is
never heard, but that, on the contrary, the lightning seems to strike
steeples by choice, and at the very time the bells are ringing, yet
still they continue to bless the new bells, and jangle the old ones
whenever it thunders.’

‘One would think,’ continues Dr. Franklin, with exquisite humour,
‘that it was now time to try some other trick. Ours is recommended,
whatever the able French philosopher may say to the contrary, by more
than twelve years’ experience, during which, among the great number of
houses furnished with iron rods in North America, not one so guarded
has been materially hurt by lightning, and many have been evidently
preserved by their means; while a number of houses, churches, barns,
ships, &c., in different places, unprovided with rods, have been struck
and greatly damaged, demolished, or burnt. Probably, the vestries of
English churches are not generally well acquainted with these facts;
otherwise, since as good Protestants they have no faith in the blessing
of bells, they would be less excusable in not providing this other
security for their respective churches, and for the good people that
may happen to be assembled in them during a tempest, especially as
these buildings, from their greater height, are more exposed to the
stroke of lightning than our common dwellings.’

While Franklin thus wrote of ‘the great number of houses furnished with
iron rods in North America,’ there was not a single public building
so protected in England. Several private persons had adopted them for
their houses, following the example of Dr. William Watson--subsequently
Sir William--vice-president of the Royal Society, who had been the
first to set up a lightning conductor in England, erecting one over
his cottage at Payneshill, near London, in 1762. But notwithstanding
the evident utility of the ‘Franklin rods,’ they were refused where
they were most wanted--for larger buildings, and particularly for
churches. The ‘unlearned men, such as commonly compose our church
vestries,’ openly declared against them, and among the clergy there
was a steady, if often silent, antagonism to their introduction. The
first movement towards its being upset was given by an occurrence which
caused much commotion, and gave rise to a vast amount of discussion.
On Sunday, June 18, 1764, a few minutes before three in the afternoon,
the splendid steeple of St. Bride’s Church, in the city of London, one
of the architectural monuments of Sir Christopher Wren, was struck by
lightning, the flash being intensely vivid, blinding several people.
The damage done was so serious that about ninety feet of the steeple
had to be taken down entirely, while great and expensive repairs
were required for the rest. Dr. Watson, as the first introducer, so
one of the chief promoters of Franklin’s invention in England, took
this opportunity of publishing in the ‘Philosophical Transactions’
a detailed account of the effects of lightning upon St. Bride’s
steeple, explaining the potency of conductors in the very action of the
electric force. He showed how the lightning first struck the metallic
weathercock at the top of the steeple, and ran down, without injuring
anything, the large iron bars by which it was supported. At the bottom
of the bars, the electric force shattered a number of huge stones into
fragments, to make its way to some other pieces of iron, inserted into
the walls to give them strength. So it went on till there were no more
metals, when havoc and destruction became the greatest. Thus, as Dr.
Watson conclusively proved, the beautiful steeple of St. Bride was
wilfully made over to ruin for want of a few hundred yards of iron, or
other metal, which would lead the electric force harmlessly from the
weathercock on the summit into the earth. He finished by telling in
the plainest terms, to all on whom devolved the duty of taking care of
churches, that it was neglectful, even to criminality, not to protect
them by conductors against the always imminent danger of being struck
by lightning.

The lay-sermon of Dr. Watson, deeply impressive by the power of the
indisputable facts on which it was based, had a considerable effect
in rousing public opinion, finding its way even into the dull ears of
‘such as commonly compose church vestries.’ Among the most important
results was a step taken, after long and solemn deliberations,
extending over several years, by the Dean and Chapter of St. Paul’s.
They made an application to the Royal Society, asking for advice as
to the best means of protecting the great cathedral, Sir Christopher
Wren’s noblest creation, against the perils of lightning. The
application was made on March 22, 1769, as recorded under that date in
the ‘Gentleman’s Magazine.’ ‘A letter from the Dean and Chapter of St.
Paul’s,’ it was stated, ‘was read at the Royal Society, requesting the
direction of that learned body for the sudden effects of lightning.
It was referred to a committee consisting of Dr. Franklyn (_sic_),
Dr. Watson, Mr. Canton, Mr. Edward Delaval, and Mr. Wilson, who,
after having examined the building, are to report their opinion.’ The
committee thus nominated embraced all the most eminent men of the
day who had studied the phenomena of electricity, and in the order
in which they ranked. Next to the great discoverer of the lightning
conductor himself, Dr. Watson could claim to stand; and next to him Mr.
John Canton, a most painstaking and intelligent worker in the field,
inventor of the pith-ball electrometer, and other instruments.

But a curious element of discord pervaded from the first this small
conclave of learned men, chosen to decide the not unimportant question
as to the best means of providing the cathedral of St. Paul with
lightning conductors. That the noble building should be so protected,
all were agreed; and it was clearly understood, besides, that if once
St. Paul’s had lightning conductors, all the other cathedrals and
principal churches of England would follow suit. What they differed
upon was not this, but the best form of lightning conductors.
Franklin’s steadfast assertion that points to the elevated rods were
not only far preferable to any other form of conductors, but the only
really protective ones, was adopted by Dr. Watson and Mr. Canton; but
they were opposed by Mr. Wilson, who asserted, with some degree of
vehemence, that points were dangerous, and that balls on the summit of
the rods afforded infinitely better protection. Standing alone in this
view among the eminent members of the committee of the Royal Society,
his arguments naturally had no effect, and the recommendation to the
Dean and Chapter of St. Paul’s was to protect the cathedral by pointed
lightning conductors. This was done accordingly. ‘Franklin rods’ were
attached to Wren’s splendid structure, worthy to be the introducer of
them, on a large scale, in Europe.

The dispute as to pointed conductors, or balls, was by no means brought
to a termination by the decision that was come to regarding St. Paul’s.
Endless pamphlets were published on the subject, and it went so far as
to being turned into a political question. As priests scented heresy
in the daring attempt to draw lightning from the clouds, so the court
faction and ultra-conservatives of England smelt republicanism in the
erection of iron rods designed by the representative of the disaffected
American colonies. The king was understood to have given his own high
opinion entirely against points, and in favour of balls, declaring his
preference by ordering a cannon ball of large size to be placed on
the top of a conductor erected over the royal palace at Kew. Meeting
such high patronage, the ‘anti-Franklinians’ only sought an occasion
to break out into open scientific warfare, and they were not long in
finding it. On May 15, 1777, a large public building at Purfleet, on
the Thames, serving as a storehouse for war material, was struck and
greatly damaged by lightning, although protected by a pointed lightning
conductor. Thereupon arose an instant outcry against the system
advocated by Dr. Franklin. From much evidence adduced, there could be
no doubt that the building at Purfleet had been hurt simply because the
conductor was defective in parts, and was besides not laid deep enough
into the ground; still this did not stop the clamour raised. Chiefly
through the agitation of Mr. Wilson, the members of the Royal Society
entered into hot discussions about the respective merits of pointed
and round conductors. The feeling of the partisans of the latter side
ran so high on this occasion, that Sir John Pringle had to resign the
presidency of the Royal Society, which post he had ably filled since
1772, for making himself an advocate of points against balls. When the
fever of the learned men had cooled down a little, it was resolved to
settle the great question of points _versus_ balls by a series of
experiments, to be held in the Pantheon, a large building in Oxford
Street, dome-like in the interior. The arrangement, in fact, carried
out under the direction of Mr. Wilson, leader of the ‘ball’ party, was
to create an artificial thunderstorm--or, as it should properly be
called, ‘lightning storm’--by means of powerful electrical batteries,
to be discharged upon conductors of various forms. His Majesty George
III., greatly interested in the subject, and cherishing fond hopes that
cannon-balls would carry off the victory in the scientific dispute,
as well as in the graver political one with Franklin’s countrymen,
undertook to pay all the expenses of the Pantheon experiments, and
they took place accordingly on an elaborate scale. But though prepared
entirely with a view of showing the inefficiency of Dr. Franklin’s
points, they proved absolutely the contrary. Artificial, like real,
lightning clearly showed its preference for a lancet over a ball; it
would glide down the former quietly, but fall heavily, mostly with an
explosion, upon the latter. However, the question being in reality less
a scientific controversy than a dispute arising from the fiery heat
of political passions, it was by no means set at rest by the Pantheon
trials. ‘Franklin rods’ were more than ever abhorred by a multitude of
persons, learned and unlearned, after the great citizen of Philadelphia
had set his hand, on July 4, 1776, to the declaration of independence
of the ‘United States of America,’ and more than a quarter of a century
had to elapse, a new generation of men growing up, before there arose
clear and unimpassioned views about lightning conductors.

While thus the battle of the rods was being fought in England, it raged
no less hotly on the continent of Europe. Here there was religious
prejudice alone at work, the political sympathies running in favour
of anything coming from America. But priestly animosity by itself
proved as strong an obstacle as any other to the erection of lightning
conductors. Where it did not exist, they sprang up with rapidity; but
wherever its influence was felt, the movement was arrested. In the
most enlightened parts of Germany, the seat and home of Protestantism,
the ‘Franklin rods’ early made their appearance. The first lightning
conductor set up over a public building in Europe was erected early
in 1769 on the steeple of the church of St. Jacob, Hamburg; and so
rapid was the spread of them that, at the end of five years from
this date, there were estimated to be over seven hundred conductors
within a circle of ten miles of the old Hanse town. To this day
they are comparatively more numerous in this district than anywhere
else in Europe. In contrast with Northern Protestant Germany, the
Roman Catholic South refused the ‘Franklin rods,’ and so did France,
although making a hero of Franklin personally. For many years after
young Robespierre pleaded the case of lightning conductors before the
tribunal of St. Omer, the strongest abhorrence to them was expressed
by the priests and their mob following in almost all parts of France,
and the active antagonism did not cease till after the outbreak of the
great revolution.

It was the same in most countries of southern and central Europe. Even
in Geneva, famous for the enlightenment of its citizens, the populace
made an attempt to pull down the first lightning conductor. It was
erected, in the summer of 1771, by the celebrated naturalist, Professor
Horace de Saussure, over his own house, after directions furnished
by Dr. Franklin. But notwithstanding that the professor was himself
highly respected, his lightning conductor created general abhorrence,
and to appease it he found it necessary to issue a public address or
‘manifesto,’ as he called it, to his fellow-citizens. The address,
dated November 21, 1771, was strangely characteristic of the times. ‘I
hear with regret,’ Professor de Saussure declared, ‘that the conductor
which I have placed over my house to protect it against lightning, as
well as to observe, occasionally, the electricity of the clouds, has
spread terror among many persons, who seem to fear that by this means
I draw upon the heads of others those dangers from which I myself
wish to escape. Now, I beg you to believe that I would never have
decided upon erecting this apparatus, if I had not been fully persuaded
both of its harmlessness and its utility. There is no possibility of
its causing damage to my own house, or of doing harm to others. All
those who are now labouring under fear would be precisely of the same
opinion, if they had entered upon the same inquiries to which I am
called in the course of my studies.’ After which the professor goes
on minutely to describe the ‘electric conductor,’ which he had been
bold enough to place over his house, dwelling upon the fact of its
having protected, as he believed, already his own residence from being
struck by lightning, and of having been found, likewise, universally
efficacious in the same manner in ‘the English colonies of North
America.’ The citizens of Geneva, much given to reasoning, earnestly
read and studied the ‘manifesto’ of Professor de Saussure, and the
consequence was, not only that he was spared further attacks and
reproaches, but that there arose soon over the churches and houses of
the town some hundreds of lightning conductors.

In Italy the progress in the erection of conductors was accompanied
by some very curious incidents. The priests here, as in other Roman
Catholic countries, actively opposed their introduction, and to do
so more effectively, they craftily attached to them a stinging name,
calling them ‘heretical rods.’ As a consequence, the mob fiercely
opposed the putting-up of any such accursed pieces of metal, and
whenever the attempt was made to fasten them to houses, it met
with forcible opposition. However, some of the highly accomplished
professors of the universities of Italy, enthusiastic in their
reception of Franklin’s discovery, proved themselves victorious
over both priests and mob. They got the Grand Duke Leopold of
Tuscany--subsequently German Emperor, under the title of Leopold I.--a
man of high scientific acquirements, to place lightning conductors
over his own palace, as well as over all the powder magazines in his
dominions. Here the mob and priest rule ceased, and only silent
curses could be levelled against the ‘heretical rods.’ Another still
more important step in advance was made by the influence of the
Abbé Giuseppe Toaldo, a warm admirer of Franklin, in correspondence
with him, and author of various scientific works, among them one on
lightning conductors. He had some influence with the ecclesiastical
authorities at Siena, in Tuscany, and brought it to bear upon them by
getting them to consent to make trial, in a manner so as not to excite
public attention, of one of the ‘heretical rods,’ over the cathedral.
This was only permitted on account of the extreme danger in which the
edifice stood, having been struck several times by lightning, and
greatly damaged. Placed on the summit of the highest of the three hills
on which stands the ancient city of Siena, the cathedral was opposed
to the dangers brought in the womb of every passing thunderstorm, and
they were all the greater as the building, erected by Pisano in the
thirteenth century, was deemed to be priceless, being one of the most
magnificent structures of the kind in Italy, of red and white marble,
filled with the choicest specimens of art, statues, pictures, gold and
jewelry. It seemed well worth risking a little heresy to guard such
treasures.

Very silently, in the dark of night, the priests of the Siena
cathedral, directed by Abbé Toaldo, laid their iron rods along the
walls of the building, but inside, planting them deep into the
ground, and with the pointed summit only a few feet above the highest
point of the steeple, so as to be scarcely perceptible from below by
the naked eye. Still the secret of what had been done could not be
entirely kept from the multitude. Some of the workmen, engaged in the
operation of fixing the iron rods to the inner walls and steeple of the
cathedral, whispered about what they had been doing, trembling at the
evil consequences of their work, notwithstanding having received full
absolution from their employers. Murmurs were now heard everywhere,
and there were signs of a popular outbreak, just when one of the many
thunderstorms regularly visiting the mountain city crept over it on
April 18, 1777. Portentously the black clouds laid themselves thicker
and thicker over the high cathedral, till all the people of Siena
crept forth from their houses, awaiting in breathless expectation the
terrors to come. Then the dark masses discharged their fiery streams;
flash followed flash, till one, a long hissing tongue of flame, fell
down upon the cathedral steeple, distinctly visible to thousands
of beholders. A few minutes after, a ray of sunshine pierced the
dark clouds, and to the bewildering astonishment of the masses, the
cathedral was standing there absolutely unhurt. As if to exhibit its
wonderful power, the gilded point of the lightning conductor stood
out brilliantly in the sun, pointing in radiant silence up to heaven.
‘Maraviglia, maraviglia!’ cried people and priests in chorus. High
mass was held forthwith in the wonderfully preserved cathedral, and
on the same day the magistrates of Siena went into the town hall and
had a record made in the book containing the annals of the city, to
make known to all posterity that their noble cathedral had just been
preserved from destruction by the astounding influence of an ‘heretical
rod.’ Though not in the least intended to be sarcastic, the irony could
not have been more complete.

There was a most remarkable historical concurrence between the gradual
introduction of lightning conductors into Europe and that of the art of
vaccination. Both the great scientific discoveries had the same end in
view for the benefit of mankind, the one teaching the art of drawing
the dangerous electric fire of the clouds harmlessly into the earth,
and the other that of extracting the poisonous seed of disease from
the human body. Both were brought forward with the noblest intentions;
and both encountered the most violent opposition from religious
fanatics, the same in substance, as interfering with the decrees of
Providence, and the ordained wrath of heaven. Both triumphed in the
end, and almost exactly at the same time, though the battle of the
great medical discovery lasted longer, and was more fiercely fought
than that of Franklin’s invention. To make the analogy between the
progress of lightning conductors and of vaccination complete, it so
happened that in at least one conspicuous instance the same man was
an important agent in forwarding the success of both discoveries. The
person in question was Dr. Johan Ingenhousz, a native of Breda, in the
Netherlands, born in 1730. A man of great natural gifts, he came to
England when about thirty years of age, practising as a physician, and
attending specially to the so-called Suttonian method of inoculation
against the small-pox, then an entirely new branch of medical science.
At the same time he eagerly embarked in electrical experiments, got
into correspondence with Benjamin Franklin, and, having made many
friends, was elected a fellow of the Royal Society in 1769. Recommended
to the king, Dr. Ingenhousz became a favourite at court, owing chiefly
to his perfect knowledge of German, which resulted in his being
recommended to a highly profitable as well as distinguished mission.
The famous Imperial lady, the Elizabeth of her age, Maria Theresa of
Austria, had read of the benefits of vaccination, then chiefly known in
England, and wishing to confer them on her own family and friends, she
asked King George the Third to recommend to her some able physician,
who could come to Vienna for the purpose. His Majesty at once named Dr.
Johan Ingenhousz, a recommendation warmly supported by the President of
the Royal Society, Sir John Pringle, who had taken an affection for the
young Dutch physician on account of his electrical researches, which
had resulted in the invention of a novel apparatus, subsequently known
as the plate electrical machine.

Dr. Ingenhousz set out for Vienna in 1772, was received with marked
honours by the great Empress, and having done his work, and wishing to
visit Italy, received an autograph letter of Maria Theresa to her son,
Grand Duke Leopold of Tuscany. At the court of this enlightened prince,
Dr. Ingenhousz resided for some time, practising vaccination, but also
engaged in electrical experiments, which created the greatest interest.
It was partly by his advice that the Grand Duke consented, in the
teeth of desperate priestly opposition, to erect one of Franklin’s
lightning conductors over his own palace, and to set them up likewise
for the protection of all the powder magazines in Tuscany. This done,
Dr. Ingenhousz went forward to Padua, invited by some of the professors
of the university, and by the famous senator of Venice, Angelo Querini,
who had a magnificent palace in the neighbourhood of the city. In this
palace, bearing the name of Altichiera, the ‘English doctor,’ as he
was called, was made to reside, practising vaccination, the same as
at the court of Florence, but following as a favourite occupation the
setting-up of ‘heretical rods.’ Altichiera itself had the first erected
in May 1774, and soon after Dr. Ingenhousz had the satisfaction of
planting another over the astronomical observatory of the university
of Padua, in the presence of an enormous crowd of students who lustily
applauded, and of an angry multitude, kept in the background less by
persuasion than the strong arms of the young men. As at Siena, so at
Padua, the mob became pacified not long after by seeing the lightning
fall upon the observatory, much exposed by its situation, and which had
often been struck before, without doing the least damage. From Padua,
Dr. Ingenhousz went to Venice, in company of his friend and patron,
Senator Angelo Querini. Here his efforts to spread the knowledge of
lightning conductors, together with vaccination, had the best results.
The church of St. Mark and other public buildings were surmounted
before long by the awe-striking ‘heretical rods,’ and on May 9, 1778,
the Senate of Venice issued a decree ordering the erection of lightning
conductors throughout the republic. It was the first recognition of the
value of conductors by any government of Europe, or, indeed, of the
world.




CHAPTER V.

METALS AS CONDUCTORS OF ELECTRICITY.


In the history of human inventions and discoveries, the idea of the
lightning conductor is almost the sole one which sprang, all but
perfect, from one brain, like Minerva, in Greek mythology, from
Jupiter’s head. Benjamin Franklin discovered the lightning conductor,
and, except some important improvements in its manufacture, due
to the progress of the metallurgical arts, the conductor remains
the same, in essence, as designed by the world-famous citizen of
Philadelphia. The reason of this is plain enough. Though one of the
most brilliant discoveries in the annals of mankind, the lightning
conductor, by itself, is one of the simplest of things. Franklin
found by experiments, that the mysterious so-called ‘electric fluid’
had a tendency to make its way in preference through metals, and so
he recommended the laying-down of a metallic line from the clouds to
the earth to prevent damage to surrounding objects, such as buildings
and the human beings within them. More than this he did not know; and
more than this we, to this day, do not know. Of the inner nature, or
constitution, of that grand cosmic discharge of electricity to which
the name of lightning is given, no scientific explanation can be given.
We are utterly ignorant of it, and in all probability ever will be.

But while the general principle laid down by Franklin, that metals
will conduct the electric force harmlessly from the clouds to the
earth, remains the same, very much has been learnt, in the progress of
scientific investigation, as regards the varying conducting capacity of
different metals. The first conductors were invariably rods of iron,
this metal being preferred by Franklin and his immediate followers
as cheap, ready at hand, and answering all purposes in practice. But
it was gradually found by experiments that there are other metals
through which the electric force will make its way more rapidly than
through iron. One of the earliest investigators of this subject was
Sir Humphrey Davy, the celebrated inventor of the miner’s safety lamp.
It was while studying the decomposition of the fixed alkalies by
galvanism, and tracing the metallic nature of their bases, to which
he gave the names of sodium and potassium, that the great chemist
and natural philosopher was brought to enter upon an examination of
what may be called the permeability of the different metals by the
electric force. The result of his investigations, as stated by him,
was that silver stood highest as a conductor of electricity; next to
it coming copper; then gold; next, lead; then platinum; then the new
metal called palladium--discovered by Wollaston, 1803, in platinum--and
lastly, iron. These were the principal metals experimented upon by
Sir Humphrey Davy, and the net result of his inquiries was expressed
summarily in the fact of copper being more than six times, and silver
more than seven times, as good a conductor as iron. Taking copper at
100, Sir Humphrey Davy drew up the following table of the electrical
conductivity of the seven metals:—

  Silver         109·10
  Copper         100·00
  Gold            72·70
  Lead            69·10
  Platinum        18·20
  Palladium       16·40
  Iron            14·60

The practical result of these experiments was that it came to be
recognised that, among the metals, copper might be employed to
greater advantage as a lightning conductor than iron: a much lesser
substance of it doing the same service of passing a given quantity of
electricity from the clouds harmlessly into the earth.

Sir Humphrey Davy was followed in his researches on the conductivity
of the different metals by the electric force, by a number of other
scientific men. His immediate successor in entering upon this line
of observations was a French naturalist of eminence, Antoine C.
Becquerel. Perhaps no man after Benjamin Franklin studied the phenomena
of electricity with such thorough insight, free from all misleading
theoretical delusions, as Becquerel. He was educated at the Polytechnic
School of Paris, and in 1810, at the age of twenty-two, entered the
army as an officer of engineers, but quitted it five years afterwards
with the rank of colonel, to devote himself entirely to scientific
pursuits. Geology and mineralogy first engaged his attention, but he
soon quitted these studies to devote himself, heart and soul, to the
observation of the phenomena of electricity, which fascinated him as
much as they had done Benjamin Franklin. The result was the discovery
of a great many facts previously unknown, making Becquerel, amongst
others, one of the founders of the science of electro-chemistry.
The result of his researches concerning the conducting power of the
electric force by different metals may be stated as follows:

  Copper       100·00
  Gold          93·60
  Silver        73·50
  Zinc          28·55
  Platinum      16·40
  Iron          15·80
  Tin           15·50
  Lead           8·30
  Mercury        3·45

It will be seen, in comparing this statement with the result of the
investigations of Sir Humphrey Davy, that while the latter places
silver before copper in conductivity, Becquerel puts copper at the
head of the list. Probably, the explanation of this difference in the
result of scientific research, by two men equally learned and equally
able, may be found in the fact that the conductivity of copper varies
greatly according to the purity of the metal. It has been ascertained
that absolutely pure copper of the finest kind--such as that existing
in the Isle of Cyprus, youngest of mother Britannia’s colonial
children--has a conducting power of upwards of twenty per cent. more
than the ordinary copper of commerce. While thus arriving at different
estimates, Sir Humphrey Davy and Becquerel are singularly in agreement
in one important respect: they both make the relative electrical
conductivity of copper and iron about the same, placing it, the one a
little under, and the other a little over 100 to 15. In other words,
they both say that the value of copper as a lightning conductor to iron
is as twenty to three, or between six and seven times as great.

Among a host of other investigators of the subject there stand
forward, besides Sir Humphrey Davy and Antoine Becquerel, two Germans,
Professors Lenz and Ohm, and another French savant, Claude Pouillet. In
the opinion of many scientific authorities, especially in the United
States, the experiments of Professor Lenz regarding the comparative
electrical conductivity of different metals were more carefully made
than any other, and are therefore deserving of the greatest credit.
He had, indeed, ample means and great leisure at his disposal, making
his scientific investigations under the patronage of the Grand Duke,
afterwards Emperor, Nicholas of Russia, while acting as his private
tutor at the university of St. Petersburg. The researches of Professor
Lenz as to the comparative power of various metals to conduct the
electric force were given in the following results--copper, as before,
standing as the centesimal unit:—

  Silver       136·25
  Copper       100·00
  Gold          79·80
  Tin           30·84
  Brass         29·33
  Iron          17·74
  Lead          14·62
  Platinum      14·16

A comparison of the figures here given with those of Sir Humphrey
Davy and of Becquerel shows that the results obtained by Professor
Lenz differ from those of both the other investigators. Like Sir
Humphrey Davy, Professor Lenz declared silver to be of greater electric
conductivity than copper, but, on the other hand, he assigned lead a
very low place, putting it under iron, instead of far above it. It is
difficult to explain this wide divergence, even on the utmost allowance
of purity, or impurity, of metals. As regards the most important
question, from a practical point of view--that of the difference
between copper and iron--Professor Lenz, it will be noticed, places
iron higher in the scale than both Sir Humphrey Davy and Becquerel.
Still, in his estimate also, copper was admitted to have about six
times the conductive power of iron.

While, as just stated, the experiments of Professor Lenz on the
electric conductivity of metals are held in the highest esteem in
America, the same is the case in Germany as regards those of Professor
Ohm. The latter is held to be there the highest authority on all
subjects connected with the measurement of the electric force. The
professor, born at Erlangen, 1787, and for many years teacher of
natural history at Munich, where he died in 1854, devoted the utmost
patience and an immense amount of time to the definite object of
ascertaining the electric conductivity of all the metals, registering
the result of his experiments in a special work, the most complete
existing on the subject. According to Professor Ohm, the principal
metals stand to each other in conductivity as follows:—

  Copper       100·00
  Gold          57·40
  Silver        35·60
  Zinc          33·30
  Brass         28·05
  Iron          17·40
  Platinum      17·10
  Tin           16·80
  Lead           9·70

Here again is a striking difference with the statements of other
investigators. It seems absolutely inexplicable indeed, how it could
happen that scientific men of eminence, and admitted authorities on the
subject they are treating, came to vary on the electric conductivity
of several of the metals. The difference is most astounding as
regards silver, the conductivity of which, compared with the per
cent. of copper, Professor Lenz places at 136·25, Sir Humphrey Davy
at 109·10, Becquerel at 73·50, and Professor Ohm at only 35·60. The
only conclusions that can be come to under the circumstances are, that
the record of Professor Ohm’s results as regards silver is incorrect;
or, that the relative degrees of purity of the samples of metal
experimented upon by him and the other professors differed very widely.
What is of more importance than this question, is the comparative rank
of copper and iron. Here, it is satisfactory to find, the results
ascertained by Ohm agree very nearly with the conclusions of the other
investigators, it being laid down that copper has about six times the
conductive power of iron.

The place filled in America by Lenz, and in Germany by Ohm, is
generally assigned in France to Professor Claude Pouillet, a savant who
devoted, perhaps, more time than any other in his own country to the
study of the phenomena of electricity. Born in 1791, Professor Pouillet
became, at a comparatively early age, the director of the celebrated
scientific institution of Paris known as the ‘Conservatoire des arts
et métiers,’ which led him to enter upon a course of experiments in
electricity, and most particularly, at the request of the government,
upon investigations as to the best material for lightning conductors.
The result of these was published in a lengthened treatise, in which
Professor Pouillet set down the electric conductivity of the principal
metals, taking copper at a hundred, as follows:—

  Gold                       103·05
  Copper                     100·00
  Silver                      81·26
  Brass         from 23·40 to 15·20
  Platinum                    22·50
  Iron          from 18·20 to 15·60
  Cast Steel                  14·75
  Mercury                      2·60

It will be seen that Professor Pouillet, differing from other
investigators, as they among themselves, regarding the relative
conductivity of the precious metals, gold, silver, and platinum, agreed
in the main with them as regards the relative proportions of copper
and iron. Most painstaking and minute in his experiments, he found
moreover that iron, as well as brass--the latter a mixed metal, and
as such variable in composition--was not always the same in respect
to conductivity, the changes being due to difference in temperature,
as well as greater or lesser metallic purity. As set down by him,
the variations in iron were between a maximum of 18·20 in regard to
100·00 of copper, and a minimum of 15·60, which gives a mean of 16·90.
Taking this mean, the comparative list of the positions held by copper
and iron in regard to electrical conductivity, according to the five
investigators, may be set forth in the following summary:—

                 Copper         Iron
  Davy           100·00        14·60
  Becquerel      100·00        15·80
  Lenz           100·00        17·74
  Ohm            100·00        17·40
  Pouillet       100·00        16·90

Taking the average of these five statements, it will be found that the
relative conductivity of copper to iron stands as 100 to 16½--that is,
a little over six to one. The approximate correctness of this figure,
being the result of all the investigations by the most eminent men who
studied the subject, can therefore admit of no reasonable doubt.

The important researches as to the greatly varying degree in which
given quantities of metals will act as conductors of the electric
force, were made possible only by the discovery of the singular
phenomena of electro-magnetism, due chiefly to the Danish philosopher
and naturalist, Hans Christian Oersted. His career, in some respects,
was not unlike that of Benjamin Franklin. The son of an apothecary,
born in 1777, he set up in the same business, not despising trade, but
devoting himself actively to it, as means to an honourable end, that
of gaining independence. Fascinated by the study of the phenomena of
electricity, Oersted devoted himself to it heart and soul, as Franklin
had done; and the result achieved, if not fully as important as the
invention of the lightning conductor, was one filling a prominent place
in modern scientific discovery. It had been observed, long before
Oersted, that there was a close connection between what was known as
magnetism and lightning, or rather, to state it more directly, it was
known that lightning exercised a strong influence upon the magnetic
needle. One of the most notable reports, and one of the first on the
subject, came from the captains of two English vessels, sailing in
company from London to the West Indies in the year 1675. When near
the Bermudas, a stroke of lightning fell upon the mast of one of the
vessels, doing considerable damage, and, as the captain believed,
swinging his ship round, the men at the helm seeing the compass
violently disturbed. He continued steering in what he believed the
old direction, but noticed, a few minutes afterwards, that the other
vessel, his former companion on the route, and which had not been
struck by lightning, was following an opposite course. He had the good
sense to approach it, and explanations ensued, the result being the
discovery that the lightning had completely reversed the polarity of
the magnetic needle, it pointing now south instead of north. The story
of this met with much doubt at the outset, but it was amply verified
before long by the report of many similar occurrences. It became
known, not only that the polarity of the magnetic needle might be
reversed by a stroke of lightning, but that the effect of the latter
frequently was to magnetise iron and steel. An instance of this kind,
on a large scale, occurred at Wakefield, Yorkshire, in the month of
June 1731, during a violent thunderstorm. The lightning here entered
the warehouse of a merchant who had just packed a case of knives,
forks, and other articles of steel and cutlery ware, for despatch to
the colonies. The case was placed immediately under the chimney, which
the lightning entered, breaking open the box, and scattering over
the floor of the room its contents, which, when afterwards examined,
were all found to be strongly magnetic. These, and many similar facts,
were all clearly established; yet a considerable time elapsed before
important conclusions were drawn therefrom. As in the case of Franklin,
so in that of Oersted, it required not merely scientific acumen, but a
thoroughly practical mind, to trace, in the one instance, the actual
connection between electricity and lightning, and in the other that
between magnetism and electricity.

It was in the year 1819 that Hans Oersted, now settled as a lecturer at
Copenhagen, announced the result of a series of investigations which
laid the foundation for the new science of electro-magnetism. He stated
that he had found that if a magnetic needle, free to move like that of
a compass, was brought parallel to a wire charged with electricity,
it would leave its natural place and take up a new one, dependent on
the position of the wire and the needle relative to each other. If
the needle, he said, was placed horizontally under the wire, the pole
of the needle nearest the negative end of the electric battery would
move westward, but, on the other hand, if the needle was placed above
the wire, the same pole would move eastward. Again, if the needle was
placed on the same horizontal plane as the wire, no motion would be
on that plane, but the inclination would be to a vertical movement.
Finally, if the wire was laid to the west of the needle, the pole
nearest the negative side of the battery would be depressed, but it
would be raised if the wire was placed to the east of the needle.
From these observations, verified in numerous experiments, Oersted
concluded that the magnetic action of the electric force moved in a
circular manner around the conducting object, which he expressed in
the formula that ‘the pole _above_ which the negative enters is turned
to the west,’ and that ‘the pole _under_ which it enters is turned
to the east.’ The discoveries of Oersted resulted in the creation of
that wonderful production of modern science--the electric telegraph.
A minor result, highly important as regards the erection, and still
more the maintenance, of lightning conductors, was the construction of
galvanometers.

What the microscope is to the student of the inner secrets of animal
and vegetable life, the galvanometer is to the investigator of the
phenomena of electricity, in their practical applications. Until its
invention, there existed no means of practically testing the strength
of the electric force, or the ‘current,’ as it is usually called,
and it was not possible, therefore, to ascertain, in any given case,
whether lightning conductors, among others, were really efficient or
not. Perhaps, had it been only for this purpose, the galvanometer
would have waited long in being constructed, but what brought it into
existence, and led it to its present perfection, was that greatest of
practical uses of electricity, the telegraph. As it arose from small
beginnings to gradually more extended employment, embracing ultimately
some of the highest interests of civilised mankind, there came the
necessity of having instruments for gauging accurately the effects of
the mysterious force thus put in harness at the bidding of science.
The galvanometer having been devised, the next step, indispensable for
its use, was to frame a standard by which electrical energy might be
measured, and to invent terms by which the amount of such energy could
be expressed. It is well known that in order to be able to measure the
dimensions of any material object, standard units are required. In this
country the units adopted are: for length, the foot; for weight, the
pound; for time, the second; and so on. To express mechanical force or
power, the foot pound is the unit employed--that is, the mechanical
energy necessary to raise a weight of one pound to a height of one
foot. On the Continent, where the units of length and weight are the
metre and the gramme, the unit of mechanical energy is the metre
gramme. Apart from the fact that the latter units are very generally
adopted by all the Continental States, the simplicity of the decimal
method of multiplying and sub-multiplying them renders the system of
particular usefulness for scientific purposes; and they are therefore
very extensively employed even in England in scientific research. Thus
experimental results obtained in one country are at once understood,
and are directly comparable with results obtained in any other country,
without the necessity of reducing the figures to terms of units of
other kinds than those in which they are expressed.

Now electrical energy being merely a form of mechanical energy--the one
being capable of conversion into the other--it follows that the units
of the functions of either of the two powers can be expressed in units
of the other; and this being the case, it is manifestly both convenient
and desirable that in forming the dimensions of the standard electrical
units, they should be constructed in terms of the metre gramme, second
units.

The proposition to do this originated with Dr. Weber, and acting upon
this proposition a committee of the British Association, comprising
nearly all the leading electricians of Great Britain, was formed some
years ago, which committee, with almost perfect experimental skill,
determined an absolute measure for the values of the several units
required for electrical measurement. Taking as the unit quantity of
electricity that amount which would be generated by a gramme weight
falling through a distance of one metre in one second, the value given
to the unit of resistance was such as would allow this unit quantity
to flow through it in one second. The means by which the values were
experimentally arrived at cannot be described here. It suffices to say,
that the unit of resistance being once determined, copies of it, formed
of lengths of wire of a platinum-iridium alloy, were issued, from which
copies the sets of resistances now so largely employed by electricians
were adjusted. Out of compliment to the great German physicist who
first proposed the fundamental law which governed the flow of the
electrical current, the unit of resistance was called the ‘Ohm.’ It was
a marked progress on the practical application of the electric force
to be enabled to measure it, and, as it were, bring it under control.

Without its help the electric telegraph could not have become what
it is; nor has it been without notable use in the art of protection
against lightning. One of the greatest steps in advance in the
application of the lightning conductor, from its discovery to the
present day, has been the invention of the galvanometer. Franklin could
not, but we can, test our lightning conductors.

[Illustration: Fig. 1.]

[Illustration: Fig. 2.]

Some of the simplest and most practical galvanometers, specially
designed for ascertaining the actual efficiency of conductors, have
been made in recent years in Germany. The author of this work had
constructed for him by Mr. H. Yeates, of Covent Garden, the one, with
some improvements, as shown in the subjoined engravings: the first,
fig. 1, exhibiting the arrangement of the battery and resistance coils,
and the second, fig. 2, giving a diagram of the battery current. The
battery consists of three cells, and is a modification of the old
manganese cell, in which the carbon and oxide of manganese occupy
the outer, and the zinc plate the inner, or porous, cell. By this
arrangement, the surface of the negative element is greatly increased,
and hence a more constant current is obtained, on account of the
battery not polarising so rapidly as in the old form. Another advantage
of this arrangement is, that the cells can be almost entirely sealed
up, the air-openings being made within the porous cell. In the centre
of the lid of the box is placed the galvanometer with a ‘tangent’
scale; and on the left are two terminals, by the connection of which
the conductor can be examined. On the right hand end of the lid are
placed five keys, marked respectively, L, B, 1, 2, 3. Under B is
one pole of the battery, so that by depressing this key, as will be
seen by the connections in the diagram (fig. 2), the battery current
is sent through the galvanometer direct. If, however, key No. 1 is
depressed, the battery is connected with the galvanometer through a
known resistance--key No. 2 has a larger resistance, and No. 3. still
larger. The fifth key, L, closes the circuit within the limit of the
instrument, but on being depressed opens it, and includes the line
or conductor placed between the two terminals at the other end, the
battery key at the same time being pressed down. By this arrangement
it will be seen that the resistance of the line or conductor may be
compared with the known resistance connected with any of the keys
Nos. 1, 2, 3, or any of these resistances may be included with that
of the line, so as to get a convenient deflection of the galvanometer
needle. In the case, with the battery, is a bobbin of insulated wire
for connecting the instrument with the conductor and earth which is
to be tested. The whole arrangement here described and illustrated
is exceedingly portable, being in the form of a small carpet bag,
and therefore particularly fitted for persons inspecting lightning
conductors and making periodical tests, without which it cannot be too
widely known there is really no trustworthy security of protection in
lightning conductors.




CHAPTER VI.

CHARACTER OF LIGHTNING AND OF THUNDERSTORMS.


It is well remarked by Arago, that although we know nothing about
lightning, beyond the well-ascertained fact that it is one of the
manifestations of the equally vast and mysterious electric forces
pervading the universe, we yet may ascertain a great deal about
its mode of action by continued observation, made by many persons
and at many places. As yet the wise recommendation of the French
astronomer has, unfortunately, not been acted upon to any extent,
or in any systematic manner; still, a good many facts and incidents
have been gathered which serve to throw a strong light upon the
apparently erratic, but in reality normal manner in which, as in
obedience to some grand unfathomable cosmic law, the fire of the
clouds flashes along its self-made path. That these observations
are entirely modern, detracts nothing from their value. With all
their famed civilisation, the classical nations of the ancient world
never came to look upon lightning and thunderstorms as regular
functions of nature, but regarded them with dread and horror. Even
the greatest of their natural philosophers found in them means only
for encouraging popular superstition. Thus Pliny the Elder, in his
celebrated ‘Natural History,’ recommends, like Arago, notes being
taken about thunderstorms, but for quite a different purpose. ‘Nothing
is more important,’ says the celebrated author of the _Historia
Naturalis_, than to observe from what region the lightnings proceed,
and towards what region they return. Their return to the eastern
quarter is a happy augury. When they come from the east, the prime
quarter of the Heavens, and likewise return thither, it is the
presage of supreme felicity.’ It is reported by travellers that this
form of superstition--which has reference, of course, to the zigzag
form of many strokes of lightning, apparently in turn advancing and
retrograding--still exists in some districts of Southern Italy.

The superstitious awe with which lightning was looked upon not only
in ancient times, but in which it is still held by the ignorant at
the present day, finds its easy explanation both in the nature of
the terrifying phenomenon, and in the fact that even now we can only
speculate upon some of the causes of its seemingly capricious actions.
There can be no doubt that thunderstorms will visit some districts
in preference to others, and that lightning will descend constantly
upon some selected spots, and will entirely keep away from others.
As regards the latter case, old historians were fond of quoting the
grand temple of Solomon at Jerusalem, which was never struck by
lightning in the course of a thousand years, although thunderstorms
burst unceasingly over the Holy City, creating immense havoc and
destruction. In this instance at least, the explanation is simple,
although it may not be so in many others. It is stated expressly in
the biblical description of the building of the world-famed temple (1
Kings vi. 21, 22) that ‘Solomon overlaid the house within with pure
gold; and he made a partition by the chains of gold before the oracle;
and he overlaid it with gold. And the whole house he overlaid with
gold, until he had finished all the house; also the whole altar that
was by the oracle he overlaid with gold.’ If wise King Solomon had
known Franklin’s discovery of the protection against lightning given by
metallic conductors, he could not have guarded his magnificent edifice
better than he did by having ‘the whole house overlaid with gold,’
as stated in the Bible. But he did even more than this, according
to the historian Josephus, who records that the roof of the Temple,
constructed in what is now called the Italian style, was ornamented
from end to end with sharply pointed and thickly gilded pieces of
iron, in lancet form. These points, the historian surmised, were
placed there to prevent the birds from settling on the magnificent
roof, and soiling it, and it is very possible that this was the
original design. Nevertheless, it is certain that King Solomon guarded,
although, probably, without intending to do so, his magnificent temple
as perfectly against lightning, as could have been accomplished by
the best arranged system of conductors. It is not often that many
thousands of pounds are spent for protection against lightning, even
if intended for great cathedrals and splendid royal palaces; but King
Solomon disbursed, by the most trustworthy calculations, no less than
thirty-eight millions sterling in covering the temple with one of the
best of conductors--including the pointed and gilded lancets along the
roof, as perfect ‘Franklin rods’ as were ever designed by any architect.

If it is easy to account for the old historical marvel of Solomon’s
temple having stood unharmed amidst the ragings of lightning from
tens of thousands of storms, it is more difficult to find the reason
why many buildings of another kind should be constantly under attack.
A notable case in point, related by the German naturalist G. Ch.
Lichtenberg, occurred at the village of Rosenberg, in the province
of Carinthia, Austria, belonging to the noble family of Orsini. The
village church, although not standing in a very elevated position, was
unceasingly struck, in the course of the seventeenth and eighteenth
centuries, by lightning, which sometimes battered in the roof,
sometimes broke down part of the steeple, and often flew in at the
window on one side and out on the other. Very possibly, there were
large pieces of metal on the wall, or in the roof; or, if not, there
may have been masses of water near, underground, sufficient to account
for the manifestations of the electric force. However, popular opinion,
utterly ignorant as to such causes, ascribed the whole to the doings
of evil spirits, and endless attempts were made to exorcise them
by prayers, fastings, and sprinkling of holy water. But it was all
unavailing. The lightning came again and again, and in the summer of
1730, a flash from the clouds, more violent than any preceding one,
demolished the entire steeple. The Orsini family, suspected by many of
the lower people of being the secret originators of all the mischief,
in league with the evil spirits, erected another steeple, handsomer and
far more solid than the one destroyed, to show their pious intentions.
But the lightning visited it as before, on the average five or six
times a year, doing so much damage that the whole church had to be
taken down in 1778, being found in ruins. Happily, in the meanwhile
the report had gone as far as the little village in Carinthia that
something had been discovered for guarding all buildings, including
spirit-haunted churches, against damage by lightning. Once more, the
proprietors of the village built a new church on the old ground, but
this time, by the advice of an Italian architect, they placed upon it
one of the ‘heretical rods,’ made famous for having done good service
in protecting the cathedral of Siena. Needless to say that it did again
similar service.

It is very probable that, besides the two causes just referred to which
divert the path of lightning, there are many others of influence,
at present entirely unknown. Numerous cases are reported where the
electric discharge from the clouds touched precisely, and with
singular accuracy, as if directed by a superior intelligence, the
same spot, without the slightest reason being discoverable for such
an action, after the most minute investigation by competent persons.
Thus, on June 29, 1763, a violent thunderstorm broke over the village
of Antrasme, near Laval, in France, the residence of a distinguished
investigator of electrical phenomena, Count de Labour-Landry, a friend
and correspondent of the Abbé Nollet as well as of Benjamin Franklin.
The lightning struck, as carefully ascertained by the Count, first
the steeple of the church, then sprang to one of the lower walls,
where it fused and blackened the gilding of picture frames and some
other metallic ornaments, melting also some pewter flasks used for
sacramental purposes, and finally opened two deep holes, as regular
as if they had been drilled with an auger, in a wooden table, placed
within a recess of soft stone. All these damages were duly repaired;
but, to the boundless surprise of the witnesses, the lightning struck
the church almost exactly a year after, on June 20, 1764, entering
the church by the same way as before, fusing and blackening the same
gildings, melting the same flasks, and, in the end, driving out the
very plugs of the wooden table inserted to fill the holes bored by
the previous stroke of lightning. The account of the whole might seem
almost incredible, were it not attested by independent eye-witnesses.
Arago, with absolute faith in their testimony, remarks thereon that
‘those who will take the trouble of reflecting upon the thousands of
combinations which might have caused the path of the lightning to have
been different in the two cases, will, I imagine, have no hesitation
in viewing, with me, the perfect identity of effect as demonstrating
the truth of a proposition I put forward,’ namely, that ‘lightning, in
its rapid march, is influenced by causes, or actions, dependent on the
terrestrial bodies near which it explodes.’ In other words, lightning,
like many other phenomena of earth, air, and water, is influenced by
unknown causes. Hamlet says very much the same, when exclaiming:

    There are more things in heaven and earth, Horatio,
    Than are dreamt of in your philosophy.

After all possible explanations, Arago could get no further than
Horatio, who thought that there was much in the universe which was
‘wondrous strange.’

It does not seem impossible that some of the extraordinary effects
of lightning, either in striking repeatedly certain objects, or in
seldom or never touching others, may be explained on meteorological
grounds. The height, as well as thickness, of the clouds charged with
the electric fire, must naturally greatly influence the direction of
the latter, and though both elements vary enormously, in different
countries and at different seasons, it is likely enough that the
variation is comparatively trifling under given conditions, as, for
example, in a district where there are prevailing winds, and where the
configuration of the earth powerfully acts upon the drift and movement
of the aerial masses, and the atmospheric conditions in general. As
to the height of the clouds charged with lightning, there appears
scarcely any limit, as it has been found that they at times rise above
the summit of the most elevated mountain ridges on the face of the
globe. The great naturalist and traveller, Alexander von Humboldt,
measured the height of a storm cloud, discharging lightning, near the
mountain of Toluca, in Mexico, and found that it was no less than
4,620 metres, or 15,153 English feet, above the level of the sea. The
height of another, ascertained by Professor de Saussure, of Geneva,
when ascending Mont Blanc, was 4,810 metres, or 15,776 English feet,
or almost exactly three miles. Probably, these are exceptional cases,
as even in mountainous districts the heavy moist and electricity-laden
clouds seldom rise to such extraordinary heights; still, even such
as they are they do not represent the extreme limit of elevation. A
member of the French Academy of Sciences, M. De Lisle, records having
measured, by trigonometrical observations, the vertical height of
clouds in a thunderstorm, with strong flashes of lightning, which broke
over Paris, and found it to be 8,080 metres, or 26,502 English feet.
Consequently, this cloud-mass, charged with electricity, stood far
above the summit of the highest mountain peak in the world.

If some of the lightning-clouds tower at a gigantic elevation over the
earth’s surface, there are others that lie almost flat on it. There are
some remarkable observations on this kind in existence, made by German
meteorologists. Two of these deserve particular notice. On August 27,
a heavy storm burst over the town of Admont, on the river Ens, in
Styria, and the lightning, falling upon the lower part of the great
convent of the Benedictines, and passing through the wall, killed two
young priests near the altar, while reading vespers. The convent lies,
like the town of Admont, in a valley, and above it, some three hundred
feet higher, stands a castle, in which resided at the time a German
professor, specially interested in the phenomena of thunderstorms. He
watched assiduously the coming storm, and saw the lightning fall upon
the great convent, noticing all the while that the gilded cross placed
on the belfry of the edifice, about 115 feet from the ground, remained
standing out clear above the electric cloud, which appeared to come
close to the earth’s surface. He noticed further that above this cloud,
enveloping the ground portion of the Benedictine convent, there hovered
another, more than two thousand feet higher, and at intervals he could
see streaks of lightning fly from between the two, not however from the
more elevated to the lower one, but in a contrary direction. It was
evident that the two clouds must have been charged by electric forces
of different ‘degree,’ or ‘potential;’ it may be, one of a ‘negative’
and the other of a ‘positive’ kind, or, as Benjamin Franklin termed
them, ‘plus’ and ‘minus;’ although, as long as the forces differ in
‘degree’ or ‘potential,’ it is not essential that they be of opposite
kinds. As the marvellously sagacious discoverer of the lightning
conductor surmised, the wondrous force is really unitarian--that is,
throughout the same, the term ‘kind’ really only indicating on which
side of an assumed zero (the potential of the earth) the observations
or measurements are made.

Another notable instance of low-lying storm-clouds, and which furnished
the rare opportunity of measuring the thickness of one of them,
occurred at the city of Gratz, Austria, on June 15, 1826. The city is
built along the side of a hill, the highest point of which, called the
Schlossberg, has on its summit a castle, now in ruins, but at the time
garrisoned by troops, and furnished with a small observatory. When
the storm in question broke over the city, several scientific men on
the Schlossberg took notes of the movement and direction of the great
cloud emitting its electric discharges. This they could easily do, as
they themselves, on their altitude, were standing in sunshine, under
a perfectly blue sky, the dark cloud-wave rolling deep under their
feet, indicating its path and size by streams of fire, following each
other in rapid succession. Exclusive of short flashes, vanishing in
the air as soon as seen, there fell nine great strokes of lightning
upon buildings in the city, in the course of about three quarters of
an hour, five of them causing conflagrations and killing a number of
people. The storm over, the observers compared their measurements, and
it was then found that the height of the storm cloud had never been
above the clock-tower of the Johanneum, an edifice connected with the
university, and containing a library and museum, while the lowest part
of it had gone down the sloping ground of the city no further than 120
feet under the summit of the clock-tower. This, then, was the exact
thickness of the storm-cloud which had caused so much destruction.
It was noticed on this occasion, as had been done often before, that
the discharges of lightning fell all upon buildings standing on moist
ground, near the river Mur, a mountain stream coming from the Noric
Alps, and dividing the city into two parts. There can be no doubt, from
thousands of observations made, that it is one of the characteristics
of the electric force to seek its way towards water--to be, as it were,
dissolved by it, or, as perhaps it might be said more truly, to be
equalised by it. A very remarkable electrical phenomenon, and one which
is often attended with fatal results to men and animals, is what is
known as the ‘return stroke’ of a lightning discharge. This is always
less violent than the direct stroke, but is nevertheless very powerful.
It is caused by the inductive action which a thunder-cloud exerts
on bodies placed within the sphere of its activity, and disastrous
effects often take place upon objects, upon men and animals on the
earth under the cloud, although perhaps miles away from the point
where the discharge takes place. These bodies are, like the ground,
charged with the opposite electricity to that of the cloud; but when
the latter is discharged by the recombination of its electricity with
that of the ground, the induction ceases, and all the bodies charged by
induction return to a neutral condition. The suddenness of this return
constitutes the dangerous ‘return stroke.’

Lord Mahon was the first to demonstrate by experiment its mode of
action; as shown in the following illustration.

[Illustration]

A B C is the electrified cloud, the two ends of which come near the
earth. The lightning discharge occurs at C. A man at F is killed by the
return stroke, while those at D, nearer to the place of discharge, but
further from the cloud, receive no injury. It may be mentioned that it
was the action of the return shock upon the limbs of a dead frog in
Galvani’s laboratory that led to the Professor’s experiments on animal
electricity, and further to the discovery by Volta of that form of
electrical action which bears his name.

The subject of the origin of atmospheric electricity has at all times
been a favourite source of speculation with scientific investigators,
and given rise to numerous hypotheses. The eminent Swiss savant,
Professor de Saussure, already referred to, held that all atmospheric
electricity was due to the evaporation of the waters of the globe
through the effect of the sun. To prove this, he made a great number of
experiments, showing that whenever water, whether pure or containing
more or less salt, whether acid or alkaline, is projected upon a
metal crucible heated to redness, the evaporation that takes place
immediately is accompanied by strong liberation of electricity. The
fact is undisputed by scientific men, but not so the conclusion.
Another eminent savant, no less distinguished than De Saussure,
Professor De la Rive, in taking up the experiments of the former,
succeeded in showing that the production of atmospheric electricity
by throwing water upon heated metal was not the simple effect of
evaporation, but due to chemical causes.

Of the numberless attempts made to elucidate the phenomena of
electricity, in connection with the formation of thunderstorms, none
seem more worthy of regard, and of thoughtful consideration, than
those of Jean Athanase Peltier, a French savant, little known to the
general world. Born in 1785, he occupied his whole life, until his
death in 1845, with the study of meteorology and electricity, making,
among others, the important discovery that a current flowing through
a circuit composed of two metals joined together heats or cools the
junction according to the direction of the current. From all the
experiments upon the phenomena of electricity, to which he devoted
his life, Peltier drew the conclusion that the earth itself, and more
particularly the fiery liquid mass forming the inner bulk of it, over
which the solid crust and the ocean lie, but both thinner in comparison
than the skin of an apple, form one immense reservoir of electricity.
As light comes from the sun, generated, as we believe, by heat, so
the electric force, he held, comes from the interior of the globe,
likewise generated by heat. The atmosphere surrounding the globe,
Peltier asserted, produced no electricity whatever, nor held it, except
temporarily. But he thought it possible that it might exist, engendered
by other flaming masses than those of the earth’s interior, in the
interminable planetary spaces, which no astronomer can measure, and of
which imagination itself, in its loftiest flights, can form no more
conception than the finite ever can of the infinite. On the whole,
Peltier’s explanation, such as it is, may fairly be accepted, in the
present state of the scientific investigation, as one of the best that
can be given. For the rest, men must content themselves to study the
phenomena of electricity, and to regard it simply as one of the great,
if mysterious, forces of nature.

[Illustration]




CHAPTER VII.

INQUIRIES INTO LIGHTNING PROTECTION.


From our present ignorance of the actual nature of electricity,
admitted alike by all scientific men, it has often been argued that no
claim can be set up for a perfect protection against the effects of
the electric force called lightning, since we do not know ‘whence it
comes, nor whither it goes.’ That this argument is entirely fallacious,
may be easily shown. The human mind does not understand, any more
than it does electricity, the great forces called centripetal and
centrifugal, which keep millions of suns and of planets in their path
through the boundless universe; yet there is no educated man who doubts
that astronomers are able to calculate, with the greatest mathematical
precision, the time when two particular stars will come near each
other, when the moon will obscure Orion, and Venus make her transit
across the sun. Again, no explanation can be given of the actual
nature, of the Why and the Wherefore, of the force called gravity,
simply in its operation on our globe. Still men can calculate, with
the greatest nicety, the result of any given weight, falling, from any
given height, on the surface of the earth or below it.

François Arago, reasoning on the disputed efficiency of lightning
conductors, puts another indisputably practical case. ‘If,’ says he,
‘we take the dimensions to be given to conductors from experience,
and if those which we adopt have been found to resist the strongest
lightning recorded for over a century, what more can reasonably be
asked for?’ When the engineer decides on the height and width of
the arches of a bridge, the vault of an aqueduct, the section of a
drain, and similar constructions, what does he concern himself with?
He examines all the facts and records on the matter as extensively as
he can, and, in making his plan, keeps somewhat beyond the dimensions
dictated by the greatest floods and the heaviest rains which have ever
been observed. He thus goes as far back in his research as the evidence
within his reach will enable him to do, but without confusing himself
either with searching for the hidden causes of floods and rains, or
with investigating the character of the physical revolutions, or the
cataclysms which occurred in prehistoric times, and of which geologists
only have been able to discover the traces and estimate the magnitude.
So with the engineer. Greater precaution or foresight than his cannot
be demanded from the constructor of lightning conductors, nor is any
needed.’

It may be laid down as an absolute fact, that a well-made lightning
conductor, properly placed, and kept in an efficient state, can never,
under any circumstances, fail in its action. Undoubtedly it has
happened that buildings to which conductors were attached have, in many
instances--of which some will be enumerated in another chapter--been
struck by lightning, and even damaged; but these cases, so far from
going against the truth that good lightning conductors are infallible,
only serve to prove it. A close investigation of all known instances
where the electric force has struck buildings, nominally protected
against lightning, shows most conclusively that the conductors placed
on them were either inefficient, in some way or the other, or did not
lead properly into moist ground--that is, had not the all-indispensable
‘earth connection.’ There is no case on record in which a really
efficient lightning conductor, properly placed, and with its terminal
in technically so-called ‘good earth,’ did not do its duty; and without
being dogmatic on the subject, it may well be asserted can no more
fail to give protection than an efficient drain-pipe can fail to carry
off the water upon the roof. Although the electric force is neither a
‘current’ nor a ‘fluid,’ often as it is so described, still the analogy
holds good so far as the one here given between the drain-pipe and the
conductor. And the reason is clear enough. The water, in running down
a hollow tube, obeys simply the law of gravity, but no less immutable
than this is that which governs the movement of the electric force. As
the water has no choice but to follow the channel made for it, under
the guidance of experience and mathematical calculation, so has the
emanation of the electric energy no option but to pursue the path which
scientific investigation has shown it always to take. Men may speak of
‘erratic’ lightning; but it is certain that the course of the electric
force is as subject to cosmic laws and as immutable as that of the
stars.

Most of the experiments and investigations for ascertaining the best
form of lightning conductors, and their application to buildings
so as to be invariably efficient, have been carried on by private
activity; still, the subject has also, at various times, undergone
the examination of official authorities, as well as of learned
societies. Little has been done in this respect in England, but very
much in France, where, ever since the publication of Franklin’s great
discovery, the question of protection against lightning has uniformly
interested the public, as well as the learned world, leading to
the production of more treatises on the subject than in any other
country, except perhaps Germany, the world’s centre of book-making.
One of the most important of the French works here referred to, and
which may be regarded as the standard work on lightning conductors,
is a semi-official publication, entitled ‘Instruction sur les
paratonnerres,’ issued in new editions from time to time, and widely
dispersed, not only in France, but all over Europe and America. It
consists of several reports about lightning conductors made, from
1823 to 1867, by committees comprising some of the most distinguished
men of science at the time, to the ‘Académie des Sciences’ of Paris.
The earliest of these reports originated from an application of
the French Government to the ‘Académie.’ In the year 1822, there
happened to be in France, and over the greater part of Continental
Europe, an extraordinary number of violent thunderstorms, accompanied
by earthquakes and simultaneous eruptions of Mount Vesuvius, the
latter on a scale not witnessed for centuries. In France, the almost
continuous thunderstorms caused great alarm among the population;
and the priests in many places held processions in and around the
churches, with special prayer-meetings, to ‘appease the wrath of
heaven.’ In consequence of all this excitement, the Minister of
the Interior, deeming that something also ought to be done besides
the walking in procession to stay the fatal effect of lightning,
ordered that all the public buildings in France should be protected
immediately by conductors, made on the most perfect model and placed
in the best manner. To get pre-eminent advice as to the efficiency of
lightning conductors, the Minister applied officially to the ‘Académie
des Sciences,’ which learned body thereupon nominated a committee
consisting of six of the most celebrated investigators of the phenomena
of electricity--MM. Poisson, Lefèvre-Gineau, Girard, Dulong, Fresnel,
and Gay-Lussac. The committee held many sittings, collecting a vast
amount of evidence on the subject, and on April 23, 1823, presented
through M. Gay-Lussac its report to the ‘Académie des Sciences,’
which was adopted and ordered to be printed, being declared a highly
important document. The French Government took the same view as the
‘Académie des Sciences,’ and not only acted upon the recommendations
of the report, but issued it to all public functionaries, to the
clergy, and others, with directions to make it generally known. In
this way hundreds of thousands of copies of the ‘Instruction sur
les paratonnerres’ found their way all over France, and from thence
in translations all over Europe, as the best existing guide for the
erection of lightning conductors.

The information thus spread by the French Government gave rise to
important results. It caused the setting-up of lightning conductors
throughout the country, on private as well as public buildings, and
it likewise led to an improved construction of them, in as far as the
‘Instruction’ recommended the rods to be made of stout pieces of metal,
well fastened to each other, and, above all, led into the ground deep
enough to reach moist earth or water. If this was well enough, and
useful enough, to meet with general acceptation, there were some points
in the advice of the learned men of the ‘Académie’ that gave rise
to much criticism, as being more founded upon theory than practical
experience. In the first place, they laid it down as a hard-and-fast
rule that the upper rod of a lightning conductor--that projecting over
the roof--‘will be an efficient protective against lightning within
the circular area of a radius double that of its height,’[1] and the
acquiescence in this supposed absolute formula had for one of its
results the erection of monstrously huge rods, made to tower high above
buildings, so as to increase the field of protection to the largest
possible extent. Another and worse fault was committed by the authors
of the ‘Instruction’ in not saying anything about the necessity of
regularly inspecting the actual condition of lightning conductors, and
testing them in respect to their efficiency. While giving minute advice
as to the mode of construction and the general design of conductors,
the contents of the ‘Instruction’ were such that, on the whole, its
readers would take it for granted that it was only necessary to
properly join the strips of metals and bring them down into the ground,
after which, thenceforth and for ever, the protection against lightning
would be complete. This grave omission, together with the erroneous
dogma as to absolute rule of protection within an area prescribed by
the height of the ‘tige,’ or upper part of the rod, had the inevitable
result of causing disasters, and before the ‘Instruction’ had been
issued many years, there came report after report to the

    [1] The original, long taken as a scientific dogma, runs: ‘Une
        tige de paratonnerre protège efficacement contre la foudre
        autour d’elle un espace circulaire d’un rayon double de sa
        hauteur.’

Government that well-constructed lightning conductors had failed to
do their duty. For a length of time these reports were either not
believed in, or the failure ascribed to partial non-compliance with
the strict rules laid down by the ‘Académie des Sciences.’ However, in
the end, when thirty years had passed, the instances of buildings with
conductors being struck became so numerous, that it was impossible to
ignore them any longer and, flying once more for advice to the savants
of the ‘Académie des Sciences,’ the French Government desired them
to investigate anew the question as to the best means of protecting
buildings against lightning. Complying with the behest, the learned
body nominated again a committee of six, the names of those selected
comprising the most eminent men who had made electricity and its
phenomena their study. They were MM. Becquerel, Babinet, Duhamel,
Despretz, Cagnard de Latour, and Pouillet.

The ‘Instruction’ of the new committee, drawn up by Professor Pouillet,
was read before the ‘Académie des Sciences’ on December 18, 1854, and
having been unanimously approved, was, like the former one, taken up by
the Government and extensively circulated. The report began by modestly
excusing the short-coming of its predecessor. ‘For the last thirty
years,’ Professor Pouillet remarked, with no fear of being gainsaid,
‘the science of electricity has made great progress--in 1823 the
discovery of electro-magnetism had only just been made, and none could
foresee the immense results that would spring from its revelations.’
Based upon these grounds, the new ‘Instruction’ entirely reversed
many of the conclusions of the old one. First of all, it declared
inadmissible the theory of a fixed area of protection, to be calculated
by the length of the upper rod. ‘Such a rule,’ Professor Pouillet
justly remarked, ‘cannot be laid down with any pretence to accuracy,
since the extent of the area of protection is dependent from a mass of
circumstances--such as, among others, the shape of the building and the
materials entering into its construction. It is clear, for example,
that the radius within which the conductor gives protection cannot be
so great for an edifice the roof or upper part of which contains large
quantities of metals, as for one which has nothing but bricks, wood, or
tiles.’ Professor Pouillet then proceeded to give detailed instructions
in respect to the design and mode of manufacturing lightning
conductors. He insisted that the rods should be of greater capacity
than those recommended by Gay-Lussac in the report of 1823, and that
there should be as few joints as possible from the point to the earth.
He considered it of the greatest importance that all the joints should
be carefully tin soldered, otherwise the metallic continuity of the
conductor could not be assured. He also advised that the top of the
air-terminal should not taper to so fine a point as formerly, but
be rather blunt. A lightning conductor, said Professor Pouillet, is
destined to act in two ways. In the first place, it offers a peaceful
means of communication between the earth and the clouds, and by virtue
of the power of points the terrestrial electricity is led gently up
into the sky to combine with its opposite. In the second it acts as
a path by which a disruptive discharge may find its way to the earth
freely. In the latter case he considered there was a risk of a sharply
tapered point becoming fused, and recommended that the angle of the
cone at the top of the air-terminal should be enlarged. He also advised
that the point should be made of red copper instead of platinum, and
based his argument on the fact of copper being a better conductor of
electricity than platinum, and considerably cheaper. A copper point,
remarks M. Pouillet, subjected to a heavy stroke of lightning, would
be much less heated than a platinum point, and would scarcely in any
case be fused. While in the report of 1823, iron ropes were recommended
almost exclusively as the best material for conductors for ships, the
‘Instruction’ of 1854 declared strongly in favour of copper as the far
superior metal for the purpose. ‘Copper,’ affirmed Professor Pouillet,
‘is superior to iron as well as to brass for the purpose of lightning
conductors, it having the advantage not only of being less influenced
by atmospheric agencies, but the still more important one of allowing
a freer passage to the electric force of over three to one. Copper
should therefore be exclusively used in the construction of lightning
conductor cables for the protection of ships.

The inquiries into lightning protection instituted by the ‘Académie
des Sciences,’ and resulting in two reports, the second valuable in
the highest degree, had the good effect, not only of drawing public
attention to the necessity of providing such safeguards, but of
bringing the whole matter under due scientific control. Henceforth the
ground was cut away under ‘lightning-rod men,’ perambulating towns
and villages, and offering their trumpery ware--mostly bits of wire
tied together, with perhaps a lacquered piece of wood on the top--to
credulous persons, as a substitute for good conductors. The French
Government set a laudable example in appealing for the future always to
scientific aid. A few months after the publication of the ‘Instruction
sur les paratonnerres,’ drawn up by Professor Pouillet, a decision was
come to for protecting the new wings of the Louvre, at Paris, with the
most perfect lightning conductor that could be made, and thereupon
appeal for counsel was once more made to the ‘Académie des Sciences.’
The case was one of special interest. The palace of the Louvre, with
its inestimable treasures of art, had been the first public building
in France provided with a lightning conductor. It was due to the
initiative of an enthusiastic admirer of Benjamin Franklin, David Le
Roy, that this was accomplished, he having excited the public feeling
as to the dangers from lightning to which the Louvre was exposed to
such a degree as to compel the Government, in 1782, to carry out his
plans, under his own superintendence. The conductors erected by Le
Roy had stood the test of experience from 1782 until the year 1854,
many a thunderstorm having passed over the extensive buildings of the
Louvre without causing the least damage. But, in the last month of
1854, one more lightning cloud swept along the banks of the river
Seine, and the electric fire, falling on one of the chimneys of the
palace, knocked off a few bricks. The damage was very trifling, but
the alarm nevertheless was great, and very naturally so. If there was
one building in France, it was said, which ought to be beyond the risk
of being struck by lightning, it was the Louvre, and, if this could
not be accomplished, the art of constructing protective conductors was
altogether vain and ineffectual. It was under these circumstances,
incited by the public outcry, that the Government hastened to submit
the new case to the ‘Académie des Sciences.’

Once more the ‘Académie’ nominated a committee on lightning conductors,
composed of the same members who had signed the ‘Instruction’ of 1854,
and drawn up by Professor Pouillet. He again drew up the report, which
was adopted by the ‘Académie’ on February 19, 1855, and contained some
notable additions to the directions previously given. They related,
as was desired, in the first instance to the Louvre alone, but were
made applicable to all large public buildings. For their efficient
protection, the professor insisted, two things should be kept in view
above all others--namely, first, that the point, always of copper,
should be of greater thickness; and, secondly, that it should have a
never-failing connection with either water or very moist earth. To
ensure the latter, it was recommended, as had been done before, that
the underground part of the conductor should be divided.

The necessity for such a division, and for forming at least two
subterranean arms--the first of it, described as ‘the principal
branch,’ going very deep into ground, into perennial water, and the
second, ‘the secondary branch,’ running nearer the surface--was
explained by Professor Pouillet very clearly in this last report.
‘After a long continuance of dry weather,’ he observed, ‘it often
happens that the lightning-bearing clouds exert their influence only
in a very feeble manner on a dry soil, which is a bad conductor; the
whole energy of their action is reserved for the mass of water which
by percolation has formed below it. It is here that the dispersion of
the electric force (_la décomposition électrique_) takes place; it
will follow the principal branch of the conductor underground, and
leave the secondary branch untouched. The case is entirely different
when, instead of dry weather, there have been heavy rains, moistening
the earth thoroughly, up to the surface. It is the latter now that
is the best, because the nearest, conductor of the electric force,
which will not go to the more permanent sheet of water, lying more or
less deep in the ground, if there is moisture above it. Under these
circumstances, it is indispensable that there should be a direct
connection between the surface soil and the lightning conductor, and
this is what is accomplished by the secondary branch. It is a power in
aid of the principal branch, and one often of the highest importance.’
The suggestion here made was one so evidently good, that it was at
once accepted by the French Government, and the Louvre not only, but
other public buildings, received lightning conductors ending in two
subterranean branches, as proposed by Professor Pouillet.

The report on the protection of the Louvre Palace did not contain
the last inquiry of the ‘Académie des Sciences’ on the subject of
lightning conductors. Twelve years after it had been issued, the
Government of France once again called upon that learned body for
advice as to the best mode of protecting powder magazines. Several
cases had happened--among others at Rocroy, on the borders of the
forest of Ardennes--of such buildings being struck, notwithstanding
that they had conductors placed upon them, and the Government,
naturally alarmed, made inquiry as to whether nothing could be done to
ensure protection against lightning, infallible under all atmospheric
conditions and every possible emergency, to these dangerous stores. The
demand was made in a letter of the Minister of War, Marshal Vaillant,
dated October 27, 1866, pressing the ‘Académie’ to give another
‘Instruction,’ without delay, the Government being ‘in fear that some
of the powder magazines are not as completely protected from lightning
as could be wished.’ Thereupon the ‘Académie des Sciences’ nominated
another commission, this time of eight members, including the Minister
of War himself--not complimentary, but as being an author, and with a
warm interest in electrical science; and, besides him, MM. Becquerel
Sen., Babinet, Duhamel, Fizeau, Edmond Becquerel, Regnault, and
Professor Pouillet. The list represented a galaxy of names unsurpassed
in the investigation of such a subject as lightning conductors, looked
upon in most countries of Europe, at least in recent years, as rather
plebeian, to be left to builders and lightning rod men. Many sittings
were held by the committee, all fully attended, so that, although
the Minister had desired to get the new report ‘_le plus promptement
possible_,’ it was not till nearly three months after the receipt of
his message that it was completed, Professor Pouillet again being the
author. It was a most remarkable paper, this one, read before and
approved of by the ‘Académie des Sciences’ on January 14, 1867.

Before entering upon the subject of the protection of powder magazines
against lightning, the new ‘Instruction’ signed by Professor
Pouillet and his colleagues laid down a few so-called ‘_propositions
générales_‘--that is, either hints, suggestions, or statements,
the French word ‘_proposition_’ being most serviceably vague for
use--on the subject of lightning and of thunderstorms. The first
thesis affirmed that ‘clouds which carry lightning with them are but
ordinary clouds (_ne sont autre chose que des nuages ordinaires_)
charged with a large quantity of electricity.’ The second thesis
boldly defined the nature of lightning. ‘The fire which flashes
from the skies is an immense electric spark, passing either from
one cloud to another, or from a cloud to the earth; it is caused
by a tendency for the restoration of the electric equilibrium (_la
recomposition des électricités contraires_).’ It was laid down in the
third ‘_proposition_’ that, when lightning falls from a cloud upon the
earth, it is but an effort of the electric force to return to its
grand reservoir. That it is similar to water, which, having risen in
the form of vapour from the earth-surrounding ocean high up into the
air, then falls down as rain upon hills and plains, and finally runs
down again in rivers to the ocean, Professor Pouillet did not say in
so many words; but there were vague hints to that effect in the new
‘Instruction.’ Its practical recommendation, offspring of the theories
thus enunciated, was that the best protection against lightning
would be afforded by the most substantial metal rods, made of iron,
surrounding a building on all sides, and passing deep into the ground.
The new declaration of the ‘Académie des Sciences,’ though merely a
repetition of former reports, was not without important consequences.
First in France, and then in other countries, the conviction became
general among scientific men, and others well informed on the subject,
that well-designed conductors, if properly made and kept in good order,
form an absolute, unconditional, and infallible protection against
lightning.

Professor Pouillet also laid it down that lightning conductors, to be
efficient, must be regularly inspected, he, with his colleagues on the
committee, having come to the conclusion that such examination should
take place at least once every year. So much stress was laid upon the
importance of an annual inspection, that a strong recommendation was
made to the Government to have a _procès-verbal_, or special report,
drawn up on each occasion in the case of all public buildings, so that
it might be known by the central authorities whether the examination
had taken place at the specified time, and what had been the
declaration of the examiners. The advice was judiciously followed, with
the result that at this moment the public buildings of France have the
most complete protection against lightning--greatly in contrast with
the public buildings in England.




CHAPTER VIII.

SIR WILLIAM SNOW HARRIS.


In singular contrast with what took place in France, the importance of
lightning conductors never created any but the most languid interest
in England. Neither the Government, nor any of the scientific bodies
of the country, at any time occupied themselves seriously with the
question as to how public and private buildings might be best protected
against the dangers of thunderstorms; and from the time, a century ago,
when the Royal Society half patronised and half spurned the merits
of Franklin’s discovery, to this day, the battle of science against
ignorance in the matter had to be fought by individuals. With one
exception, that of Sir William Snow Harris, it proved no profitable
battle to any man; and in his case even, it was only so by accident.
Born at Plymouth, in 1792, and educated for the medical profession,
he early turned his attention to the subject of electricity and
lightning conductors, and more particularly to the use of them in the
Royal Navy. Owing to his early surroundings, leading to connection
with naval officers, he learnt that the damages caused by lightning
to ships of war were very numerous, and most expensive to repair; and
having got once hold of these facts, he gave them to the public in
the ‘Nautical Magazine,’ but chiefly in pamphlet form, insisting upon
the simple remedy of lightning conductors. As usual, the Government
lent a deaf ear to the proposal as long as it was possible, and it
was only when at length, in 1839, the outcry upon the subject became
overwhelming, that a naval commission was appointed ‘to investigate the
best method of applying lightning conductors to Her Majesty ships.’
The commission drew up an immense report, filling eighty folio pages
of a blue-book, the kernel of which was that, though such protectors
in thunderstorms were rather new-fangled things, they might be tried
without special harm coming to anybody. Thereupon most of the vessels
received lightning conductors, made after designs by Mr. Snow Harris.
The indefatigable advocate of conductors had his reward. He was
knighted in 1847; he had, at various times, considerable grants from
the Government; and he had the final satisfaction of being allowed
to design lightning conductors for the new Houses of Parliament. The
latter remain the most enduring monument of the only man in this
country who ever succeeded in drawing the attention of the public
and the Government to the grave subject of lightning conductors. He
could not have done so, at least not in the line he took up, had he
lived half a century later. With the gradual disappearance of the old
wooden ships disappeared also the necessity of lightning conductors
for men-of-war. An iron-built vessel, metal-rigged, is a conductor by
itself, while as to armour-clad ships of latest design, they are more
absolutely protected against lightning even than the famous gilded
temple of Solomon at Jerusalem.

In the story of the progress of lightning protection in England, the
career of William Snow Harris forms a chapter of no little interest,
as showing both the inertness of the administration, as well as of
the public, in the most important matters, and the good effects that
may result from the persevering energy of a single man. When Mr.
Snow Harris began his agitation for lightning conductors, about the
year 1820, the ships of the Royal Navy were virtually without them,
although they had something supposed to stand in their place. Just
sixty years before, in 1762, Dr. William Watson, the indefatigable
advocate of Franklin’s discovery, had strongly recommended to Lord
Anson, first Lord of the Admiralty, that all men-of-war should have
lightning conductors; and his urgent zeal, backed by influential
friends, effected that his advice was listened to. Being requested to
send in the best design for a ship’s conductor, Dr. Watson did so with
alacrity, but, unfortunately, with little wisdom. Knowing little or
nothing of ships and their management at sea, the learned member of
the Royal Society advised that the lightning conductors for the navy
should be constructed of strips of copper rod, one-fourth of an inch
in diameter, hooked together every few feet by links, and the whole
attached, for more security, to a hempen line, to be hung on to a
metal spike on the top of the mast, and from thence to fall down into
the sea. In theory, it was not a bad design, but it utterly failed in
practice. Evidently, Dr. Watson had never been on board of a large ship
in a gale, for had he been, he might have known that it would be next
to impossible to keep his chain in its place, exposed as it was to the
operation of violent mechanical forces, not to speak of possible bad
treatment from indignant sailors, with whose movement in the rigging
it interfered. It was a natural consequence of Dr. Watson’s ignorance,
that his conductors entirely failed. In most cases the commanders of
men-of-war, supplied with the copper-hempen chains, quietly stowed them
away in some corner of the ship, with orders to take them out when
needed, and it often happened that this was done only after the ship
had been struck by lightning. Year after year there came reports of
such casualties; and at last they got so numerous as really to attract
the attention of the naval authorities. Still, nothing was done until
William Snow Harris took up the matter. Sitting in his little cottage
at Plymouth, overlooking the sea, the happy thought struck the young
medical man, waiting for patients who did not come, that here might
be found a profitable as well as useful opening for his activity.
He possessed, happily, a few naval friends, ready with counsel and
assistance, and so he went to action, fighting for lightning conductors.

The battle, resulting as it did in ultimate victory, was a long one,
nevertheless. For many years, all his efforts to induce the British
Government to adopt a system of efficient lightning conductors for the
Royal Navy remained entirely fruitless; and it was only after he had
gained the sympathy of the press, and, through it, of the public, by
publishing long lists of the disasters that had befallen the cherished
‘wooden walls of England,’ that at last the closed doors of the
Admiralty were opened to him. The lists he furnished were appalling
indeed, and enough to impress any minds and open any doors. It was
shown by Mr. Snow Harris, from carefully compiled records, based upon
official documents, that in the course of forty years--from 1793 to
1832--over 250 ships had suffered from lightning. In 150 cases, the
majority of which occurred between the years 1799 and 1815, about 100
main-masts of line-of-battle ships and frigates, with a still larger
number of topmasts and smaller spars, together with an immense quantity
of stores, were destroyed by lightning. One ship in eight was set on
fire in some part of the rigging or sails, and over 200 seamen were
either killed or severely disabled. But, formidable as was this account
of damage done by lightning, it by no means completed the list of
casualties. Mr. Snow Harris gave it as his opinion, on the authority of
a great many naval officers with whom he came into contact at Plymouth,
that many ships reported officially as ‘missing’ had been struck by
lightning and gone to the bottom, with nobody left behind to tell the
tale. Thus, from a reference to the log of the line-of-battle ship
the ‘Lacedæmonian,’ under the command of Admiral Jackson, it appeared
that this man-of-war sailed alongside a frigate, the ‘Peacock,’ on the
coast of Georgia, in the summer of 1814, and that the latter suddenly
disappeared in a storm of lightning, leaving no trace behind. Again,
the ‘Loup Cervier,’ another man-of-war, was last seen off Charlestown,
in America, on the evening of a severe thunderstorm, and never heard
of again. A famous ship, the ‘Resistance,’ of forty-four guns, was
struck by lightning in the Straits of Malacca, and the powder-magazine
blowing up, it went to the bottom, only three of the crew reaching the
shore, picked up by a passing Malay boat. But for these few survivors,
Mr. Snow Harris justly remarked, nothing would have been known of
the fate of the vessel, which would have been simply reported as
‘missing’ in the Admiralty lists. It was scarcely to be wondered at
that the recital of all these tales of disasters, which might have been
prevented by the most ordinary foresight in applying known means of
protection against lightning, considerably excited the public mind, so
that at last the Government was compelled to act in the direction into
which it was impelled by the energetic Plymouth doctor. It was thus
that at last, in 1839, the naval commission already referred to was
appointed to give counsel as to ‘applying lightning conductors to Her
Majesty’s ships.’

Perhaps even this step in advance might not have favoured much the
cause pleaded by Mr. Snow Harris, had he not had the good fortune of
finding a powerful patron in Sir George Cockburn, one of the Lords
of the Admiralty. Sir George, born in London, of Scottish parents,
in 1772, had all his life long taken a great interest in scientific
pursuits; and the application of conductors especially had interested
him much, as he had himself been a witness to frequent damage done
to ships under his command by lightning. The ‘Minerva,’ of which he
was captain at the blockade of Leghorn, in 1796, had been so struck,
and likewise two ships of the flotilla, reducing the French island of
Martinique, in 1809, under his direction. Having taken a prominent part
in the American War of 1813–14, especially the capture of Washington,
Sir George Cockburn retired from active service, and in 1818 was made
one of the Lords Commissioners of the Admiralty, immediately after
being returned a Member of Parliament for Portsmouth. He henceforth
devoted himself more than ever to scientific studies; and, having been
elected a Fellow of the Royal Society, got into acquaintance with many
of its members, among them with Mr. Snow Harris, whom he came to like
on account of his fervid enthusiasm in the cause he was advocating.
The acquaintance proved of the highest advantage to the young Plymouth
electrician. Before even the naval commission, nominated to give
counsel upon the subject of lightning conductors, had given in its
report, he was allowed to make trial, on board of several men-of-war,
with a system designed by himself, and for which he had taken out a
patent. It was not long afterwards that it was officially adopted for
all the vessels of the Royal Navy, with, it is needless to say, the
greatest pecuniary advantages to the designer.

The system of Mr. Snow Harris for protecting ships against lightning
was similar to that suggested by Mr. Henly in 1774. Instead of hanging
dangling chains from the top of the rigging into the water, he nailed
on to the masts and down to the keel, slightly inlaid in the wood, a
double set of copper plates, overlying each other in such a manner that
the ends of one set were touched by the middle of the other. The plates
were four feet in length, two to five inches wide, and one-eighth of
an inch thick; they had holes drilled in them at distances of six
inches apart, and were secured to the masts and further down by short
copper nails. In order to prevent any break in the conductor at the
junction of the successive masts, a copper plate was led over the cap,
and the continuity preserved at all times by means of a copper hinge
or tumbler which fell against the conductor. It was an altogether
unobjectionable plan for securing protection against lightning, except
that it was liable to fail under imperfect execution. Bad workmanship
necessarily was fatal to it. The numerous copper plates had to be very
neatly and carefully fastened together to ensure metallic continuity,
in the absence of which the electric force might leave the path traced
for it, diverging into neighbouring metallic masses, numerous on board
ships, such as chains and anchors. It was a most costly system from
beginning to end; but as it was, and, for the short time it remained
in use, it accomplished all that was desired. Not one of the ships
fitted with the conductors designed by Mr. Snow Harris was damaged by
lightning, although many were struck, the electric spark in several
cases being so powerful as to melt the too fine metal points on the
top of the masts. However, the new lightning conductors had not to
stand the ordeal of practice for any length of time. One by one the
great wooden ships of war, once the pride and glory of England, went
into peaceful retirement, to be replaced by iron machines, propelled
by steam, metalled from the top of the masts to the water’s edge. It
had been one of the recommendations of Mr. Snow Harris to the Admiralty
that his copper plates, though expensive at first, would always be
worth their money as old metal; and the irony of fate would have
it that the conversion of copper into silver was not to be long in
waiting. Before the death of the inventor, which occurred in January
1867, his lightning conductors were fast disappearing from the ships
on which they were placed. From the windows of his villa at Plymouth,
Sir William Snow Harris could see a fleet of ironclads, dispensing with
conductors, floating on the sea.

Notwithstanding the short use of his own special naval work which gave
him fame, Sir William Snow Harris effected much in the interest of
lightning protection in general. He was one of the few men in England
who insisted that it was the duty of the Government, as well as of
private individuals, to place lightning conductors upon all objects
liable to be struck, arguing that it was little less than criminal
to neglect such a simple protection against overwhelming danger. It
was with some degree of vehemence, though not more perhaps than was
requisite, that he stood out against those who objected to conductors
because they ‘attracted’ lightning. Such assertion will, at the present
day, be regarded as foolish by all persons possessed of the least
scientific knowledge; but this was not by any means the case forty or
fifty years ago, when even well-educated men denounced conductors.
A civil engineer in the service of the British Government, Mr. F.
McTaggart, sent to Canada in 1826, recommended openly the pulling-down
of all lightning conductors in that colony, and this too in the name
of ‘science,’ of which he held himself to be an enlightened disciple.
‘Science,’ wrote Mr. McTaggart, in a book he published,[2] ‘has every
cause to dread the thunder-rods of Franklin; they attract destruction,
and houses are safer without than with them. Were they able to carry
off the fluid they have the means of attracting, then there could be no
danger; but this they are by no means able to do.’ Had such reasonings
as these been merely the senseless talk of a few individuals, the harm
done might not have been great. But it was quite otherwise. Men of
power and position, if not of high education, were imbued profoundly
with the same ideas as Mr. McTaggart, as evidenced in at least one
striking instance, which would be scarcely credible were it not on
official record. In the year 1838, the Governor-General and Council of
the East India Company actually ordered that all the lightning rods
should be removed from their public buildings, including the arsenals
and powder magazines, throughout India. The rulers of the great country
had come to their decision, as they stated, by the advice of their
‘scientific officers,’ who all apparently shared Mr. McTaggart’s belief
of the perils of ‘the thunder rods of Franklin.’ It was partly on the
representation of the energetic vindicator of lightning conductors
in Plymouth, that the order for their destruction in India was soon
countermanded by the authorities in Leadenhall Street, but not before
several buildings had been destroyed, among them a large magazine at
Dumdum, and a corning-house at Magazine. As often before, so now,
lightning itself proved the most powerful advocate of conductors, and
in India they were more quickly set up than they had been thrown down.

    [2] _Three Years in Canada._ 8vo. London, 1829.

While designing lightning conductors for the ships of the Royal Navy,
Mr. William Snow Harris was called upon likewise by the Secretary of
State for War to give advice as to the best protection that might
be given to powder magazines and other stores of war material. He
did as requested, writing a very lucid paper on the subject, which
met with the honour, unique in its way, of being put forward as an
official document. To this day there is regularly issued with the
‘Army Circulars’ from the War Office a series of ‘Instructions as
to the Applications of Lightning Conductors for the Protection of
Powder Magazines, &c.,’ reproducing textually the recommendations
of Mr. Snow Harris. These ‘Instructions,’ containing the essence of
what he wrote about conductors, and, in fact, the result of all his
investigations on the subject, treat the whole _ab ovo_, and as such
deserve quotation. ‘Thunder and lightning,’ Mr. Snow Harris wrote to
the War Office, ‘result from the operation of a peculiar natural agency
through an interval of the atmosphere contained between the surface
of a certain area of clouds, and a corresponding area of the earth’s
surface directly opposed to the clouds. It is always to be remembered
that the earth’s surface and the clouds are the terminating planes of
the action, and that buildings are only assailed by lightning because
they are points, as it were in, or form part of, the earth’s surface,
in which the whole action below finally vanishes. Hence, buildings,
under any circumstances, will be always open to strokes of lightning,
and no human power can prevent it, whether having conductors or not, or
whether having metals about them or not, as experience shows.’

Mr. Snow Harris then went on philosophising. ‘Whenever,’ he said, ‘the
peculiar agency--whatever it be--active in this operation of nature,
and characterised by the general term electricity or electric fluid,
is confined to substances which are found to resist its progress,
such, for example, as air, glass, resinous bodies, dry wood, stones,
&c., then an explosive form of action is the result, attended by such
an evolution of light and heat, and by such an enormous expansive
force, that the most compact and massive bodies are rent in pieces,
and inflammable matter ignited. Nothing appears to stand against it:
granite rocks are split open, oak and other trees of enormous size rent
in shivers, and masonry of every kind frequently laid in ruins. The
lower masts of ships of the line, 3 feet in diameter and 110 feet long,
bound with hoops of iron half an inch thick and five inches wide, the
whole weighing about 18 tons, have been in many instances torn asunder,
and the hoops of iron burst open and scattered on the decks. It is, in
fact, this terrible expansive power which we have to dread in cases of
buildings struck by lightning, rather than the actual heat attendant on
the discharge itself.’

He continued: ‘When, however, the electrical agency is confined to
bodies, such as the metals, and which are found to oppose but small
resistance to its progress, then this violent expansive or disruptive
action is either greatly reduced or avoided altogether; the explosive
form of action we term lightning vanishes, and becomes, as it were,
transformed into a sort of continuous current action of a comparatively
quiescent kind, which, if the metallic substance it traverses be of
certain _known_ dimensions, will not be productive of any damage to
the metal; if, however, it be of small capacity--as in the case of a
small wire--it may become heated and fused; in this case the electrical
agency, as before, is so resisted in its course as to admit of its
taking on a greater or less degree of explosive and heating effect,
as in the former case. It is to be here observed, that all kinds of
matter oppose some resistance to the progress of what is termed the
electrical discharge, but the resistance through capacious metallic
bodies is comparatively so small as to admit of being neglected under
ordinary circumstances; hence it is, that such bodies have been termed
conductors of electricity, whilst bodies such as air, glass, &c.,
which are found to oppose very considerable resistance to electrical
action, are placed at the opposite extremity of the scale, and termed
non-conductors or insulators. The resistance of a metallic copper wire
to an ordinary electrical discharge from a battery was found so small,
that the shock traversed the wire at the rate of 576,000 miles in a
second. The resistance, however, through a metallic line of conduction,
small as it be, increases with the length, and diminishes with the area
of the section of the conductor, or as the quantity of metal increases.’

After these theoretical explanations, Mr. Snow Harris went into the
practical part of the business of protecting buildings, and, more
especially, powder magazines and others containing explosive materials,
against the effects of lightning. ‘It follows,’ he remarked,’from these
established facts, that if a building were metallic in all its parts,
an iron magazine for example, then no damage could possibly arise to
it from any stroke of lightning which has come within the experience
of mankind. A man in armour is safe from damage by lightning. In fact,
from the instant the electrical discharge, in breaking with disruptive
and explosive violence through the resisting air, seizes upon the mass
in any point of it, from that instant the explosive action vanishes,
and the forces in operation are neutralised upon the terminating planes
of action--viz., the surface of the earth and opposed clouds. All this
plainly teaches us that, in order to guard a building effectually
against damage by lightning, we must endeavour to bring the general
structure, as nearly as may be, into that passive or non-resisting
state it would assume, supposing the whole were a mass of metal. To
this end, one or more conducting channels of copper, depending upon the
magnitude and extent of the building, should be systematically applied
to the walls. These conducting channels should consist either of double
copper plates, united in series one over the other, as in the method of
fixing such conductors to the masts of her Majesty’s ships, the plates
being not less than 3½ inches wide, and of 1/16th and ⅛th of an inch
in thickness; or the conductors may with advantage be constructed of
stout copper pipe, not less than 1/16th of an inch thick, and 1½ to 2
inches in diameter; in either case the conductors should be securely
fixed to the walls of the building, either by braces, or copper nails,
or clamps. They should terminate in solid metal rods above, projecting
freely into the air, at a moderate and convenient height above the
point to which they are fixed, and below they should terminate in one
or two branches leading outward about a foot under the surface of the
earth; if possible, they should be connected with a spring of water or
other moist ground. It would be proper, in certain dry situations, to
lead out, in several directions under the ground, old iron or other
metallic chains, so as to expose a large extent of metallic contact in
the surface of the earth.’

A few pregnant sentences, which by themselves deserved the honour of
permanently figuring in the ‘Instructions’ sent out by the War Office,
completed the advice given by Mr. William Snow Harris in respect to the
setting up of lightning conductors. ‘A building,’ he truly remarked,
‘may be struck and damaged by lightning without having a particle of
metal in its construction. If there be metals in it, however, and they
happen to be in such situations as will enable them to facilitate the
progress of the electrical discharge, so far as they go, then the
discharge will fall on them in preference to bodies offering more
resistance, but not otherwise. If metallic substances be not present,
or, if present, they happen to occupy places in which they cannot be of
any use in helping on the discharge in the course it wants to go, then
the electricity seizes upon other bodies, which lie in that course,
or which can help it, however small their power of doing so, and in
this attempt such bodies are commonly, but not always, shattered in
pieces.’ He summed up as follows:—‘The great law of the discharge is,
progress between the terminating planes of action--viz., the clouds
and earth--and in such line or lines as, upon the whole, offer the
least mechanical impediment or resistance to this operation, just as
water, falling over the side of a hill in a rain storm, picks out, or
selects as it were by the force of gravity, all the little furrows
or channels which lie convenient to its course, and avoids those
which do not. If in the case of lightning you provide, through the
instrumentality of efficient conductors, a free and uninterrupted
course for the electrical discharge, then it will follow that course
without damage to the general structure; if you do not, then this
irresistible agency will find a course for itself through the edifice
in some line or lines of least resistance to it, and will shake all
imperfect conducting matter in pieces in doing so. Moreover, it is to
be especially remarked in this case, that the damage ensues, not where
the metals are, but where they ceased to be continued; the more metal
in a building, therefore, the better, more especially when connected
by an uninterrupted circuit with any medium of communication with the
earth.’

‘Such is, in fact,’ he concluded, ‘the great condition to be satisfied
in the application of lightning conductors, which is virtually nothing
more than the perfecting a line or lines of small resistance in
given directions, less than the resistance in any other lines in the
building, which can be assigned in any other direction, and in which,
by a law of nature, the electrical agency will move in preference to
any others. The popular objections to lightning conductors on the
ground that they invite lightning to the building, that we do not know
the quantity of electricity in the clouds, and that hence they may
cause destruction, are now quite untenable, and have only arisen out of
a want of knowledge of the nature of electrical action. What should we
think of a person objecting to the use of gutters and rain-pipes for a
house, on the ground of their attracting or inviting a flow of water
upon the building; and since we do not know the amount of rain in the
clouds, it is possible that the building may be thereby inundated,--yet
such is virtually the argument against lightning conductors.’

Mr. Snow Harris, as already mentioned, received the honour of
knighthood in 1847; and after this date lived in comparative retirement
for twenty years at his residence, Windsor Villas, Plymouth. However,
he was called upon, in 1855, to undertake one more important work in
designing a perfect system of lightning conductors for the new Houses
of Parliament at Westminster. It was on the initiative of Sir Charles
Barry, the architect, that the proposal was made by the Board of Works
to Sir William Snow Harris, who accepted it with all his old eagerness
for serving the cause of lightning protection. Accordingly, he drew up
a plan, which he himself characterised, in a letter to the President
of the Board of Works, dated February 14, 1855, as ‘somewhat costly,’
but which he felt sure would be absolutely certain ‘for insuring the
safety of the buildings against one of the most terribly destructive
elements of nature.’ In its essence, the plan consisted in protecting
all the most elevated parts of the Houses of Parliament, including the
towers, by ‘a capacious metallic conductor of copper tube, two inches
in diameter, and not less than one-eighth of an inch in thickness,’ to
be fastened together ‘by solid screw plugs and coupling pieces,’ and
‘secured to the masonry by efficient metallic staples.’ To do this,
Sir William Snow Harris calculated, would involve an expenditure of
somewhat over 2,000_l._, but nothing less would accomplish it. ‘What
I have recommended,’ he wound up his letter, ‘has been the result of
very serious and attentive deliberation, and I conscientiously think
that what I have proposed is absolutely requisite to a permanent
and satisfactory security of the buildings against the destructive
agency of lightning.’ The Board of Works entirely adopted all the
recommendations of Sir William Snow Harris, and, in accordance with
them, there was included in the Civil Service Estimates laid before the
House of Commons in the session of 1855 a vote of 2,314_l._, on account
of ‘works necessary for securing the new Houses of Parliament against
danger from lightning.’

The vote passed without demur. It was in the height of the Crimean War
fever, political questions absorbing all others. Perhaps in a time
of less excitement some voice might have been raised in the House of
Commons asking whether it was wise to spend over 2,000_l._ in putting
up lightning conductors, without previously ascertaining, from the
best scientific authorities, that the system adopted was the best,
and absolutely efficacious. The strongly recommended ‘copper tubes,’
with their ‘screw plugs and coupling pieces,’ were at least a novelty,
not having stood the test of experience, and there were practical
men who shook their heads when they heard of them. However, with
war discussions raging fiercely, and reports of battles and sieges
absorbing all attention, the House of Commons had no time to bestow
upon such trifling matters as that involved in the plans of Sir William
Snow Harris; and thus the vote passed unchallenged. Perhaps silent
repentance came afterwards to the official mind. At any rate, as it was
the first, so it was the last time of Parliament granting money for
lightning conductors.

[Illustration]




CHAPTER IX.

THE BEST MATERIAL FOR CONDUCTORS.


‘The art of protection against lightning,’ says a recent German
writer, in a book on conductors, ‘is precisely the same now as it was
a hundred years ago: still, it has made immense progress since that
time.’ Though apparently involving a paradox, the words nevertheless
are literally true. The art, or rather science, of guarding objects
against the destructive effects of lightning is theoretically the same
as it was in the days of Benjamin Franklin; nevertheless, the practical
execution of the appliances necessary to attain this aim has undergone
extraordinary improvements since that time. This has been due simply to
the astounding progress of the metallurgical arts for the last forty or
fifty years. With the help of machinery on a colossal scale, such as
was never dreamt of before, our factories have come to produce metallic
masses of dimensions and shapes such as make all former achievements of
the kind appear utterly insignificant. We build huge iron ships, armed
with cannon of ponderous weight; we throw iron bridges across rivers
and arms of the sea; we lay metallic cables through the ocean and over
the earth, encircling the globe. All these wonderful achievements, in
which the development of engineering science went hand in hand with
that of tool-making and the ever-growing employment of the power of
steam, have gone to the constant improvement of lightning conductors.
They have benefited, indirectly, in the result of great inventions, and
of immense toil and labour, originally directed to other ends.

There is something half touching, half comical, in reading of the
troubles which Benjamin Franklin had to undergo before he was able to
set up his first lightning conductor. He could meet with no assistance
but that of the blacksmith of little Philadelphia; and the ability
of the latter in the art of forging iron rods more than a few feet
in length was of the most limited kind. The ingenuity of Franklin
overcame this difficulty by a variety of clever contrivances, such
as connecting a number of small rods by caps and joints, fitting
closely; but others were not so successful as he in the matter. Even
in Paris there were no artisans to be found, for many years after
lightning conductors were first recommended, able to make them, and
foreigners, chiefly English, had to be brought there for the purpose.
The difficulties arising from this backward state of the industrial
arts were greatly increased by the belief, prevalent for a long time,
that lightning conductors, to be efficient, ought to be of very great
height, their so-called ‘area of protection’ being in proportion to
their height. The supposition, originating in France, was carried to
extremes in that country, chiefly through the teachings of M. J. B.
Le Roy, a very able but eccentric man. Guided by vague analogies in
electrical phenomena, M. Le Roy, who enjoyed in his time--the latter
part of the eighteenth century--the reputation of being an authority on
the subject of lightning conductors, laid it down as an indisputable
fact that the ‘Franklin rods’ only protected buildings if rising high
above them. He recommended the length of the rods above the chimney, or
summit of any edifice, to be not less than fifteen feet, guaranteeing
that, if of this height, they would offer absolute protection against
lightning over an area of four times the same diameter--that is, sixty
feet. Modern experience has proved this to be an absurdity; still,
in the infancy of all knowledge about lightning conductors it was,
perhaps, not unnatural that even learned men should believe in such
fancies. Lightning was looked upon, not only in name but in reality,
as an electric ‘fluid’ and the conductor was supposed to draw this
‘fluid’ from the clouds. Therefore it was but cogent reasoning to raise
conductors as high above the roofs, and as near to the storm-clouds, as
could possibly be done. If possessed of modern means for manufacturing
pieces of metal of almost any length, M. Le Roy would not improbably
have recommended to elevate lightning conductors a couple of hundred
feet, instead of only fifteen, above the summit of buildings.

It was owing chiefly to the difficulty of forging long iron pieces,
and of welding them together in a satisfactory manner, that, for many
years after lightning conductors had been introduced into Europe,
there were constant attempts made to find substitutes for the rods
devised by Franklin. Chains were largely used towards the end of the
last and the beginning of the present century, both in France and
Germany, their employment having been suggested by the example of the
English navy, where they were introduced, as already mentioned, upon
the recommendation of Dr. Watson. The Continental mode of using iron
chains for the protection of buildings against lightning was to hang
them between the upper part of the conductor, surmounting the roof,
which continued to be a straight piece of metal or rod, and the lower
portion buried in the ground, sometimes, but not always, likewise a
chain, but thicker than the rest. The characteristic of this method,
and showing its long existence, is that it gave rise to a nomenclature
existing to this day in France and Germany, where in all books on
lightning conductors they are described as consisting of three distinct
parts. The French call the upper part of the rod, over the roof, ‘_la
tige_,’ the stem or stalk; and the Germans, ‘_die Auffangstange_’
literally the reception-rod. In both languages the middle part,
from the roof downwards to the earth’s surface, is described as the
conductor proper, ‘_le conducteur_’ and ‘_der Leiter_.’ Again, the
lowest underground part of the conductor is designated, by the French,
‘_la racine_,’ the root, and by the Germans as ‘_der Bodenleiter_,’
or the ground-conductor. It has often been said that, as language
springs from ideas, so it reacts upon them, and if the proposition
be true, as most will admit, the French and German designations of
the parts of lightning conductors--also to be found in Italian, and
adopted in a few of the older English treatises on the subject, mostly
translations--have a strongly misleading tendency. Nothing could be
further from the truth than the assertion that a conductor ought to
consist of three distinct parts. On the contrary, the more it is ‘one
and undivided,’ the better it will be as a lightning protector.

The use of iron chains as conductors gave rise to very many fatal
accidents, and for a time resulted in an outcry that the system
itself could not be depended upon, as it was known to be not always
efficacious. Lists were published of numerous instances in which
buildings with what were supposed to be the best conductors were struck
by lightning, from which it was argued that Franklin’s great discovery
of the electric force always seeking a metallic path to the earth
was a myth. It was not till some painstaking scientific men, deeply
interested in the subject, had set to work to discover the causes
of the failure, that the whole became plain enough. The chains, in
some of the instances in which they had proved inefficient lightning
conductors, were found to be corroded to such an extent as barely to
hang together. Of course this corrosion would impair the efficiency
of the conductor by reducing the quantity of metal; but the chief
objection to the use of chains lies in the fact long ago pointed out
by Mr. Newall, that even supposing a chain were formed of links of
half-inch copper rods, and were perfectly bright and clean, the area
of the conductor is reduced to a mere point where the links touch each
other, and the resistance becomes so great in such a small conductor
that instances have been recorded of the fusion of the links. In other
cases, as in that of H.M.S. ‘Ætna’ in 1830, the chain was boomed out,
and did not touch the water!

Simultaneously with the chains, there was trial made, in several
Continental states, and also in England, of several other metallic
conductors besides iron. Tin and lead had both their advocates, but
the latter more than the former, on account of its far lower price. As
regards tin, it had really no advantages whatever over iron, except
pliability and non-oxidation. Against this was to be set that it was
much more expensive than iron, with only about the same conducting
power, according to Becquerel, Ohm, and other investigators. Professor
Lenz, it is true, ranked tin very much higher, asserting, from
experiments of his own, that its power of conductivity was nearly twice
that of iron; and it was partly owing to his great influence that
the metal obtained a trial in several countries, more particularly
in Russia and in the United States of America. Still, the result was
not satisfactory on many accounts, and its price alone brought tin
to be soon abandoned as a conductor. Lead had a far longer trial.
Its cheapness recommended it strongly, and equally so its extreme
pliability. One of the greatest difficulties of the constructors of
‘Franklin rods,’ when first they came into demand, was to make the
iron pieces fit properly around sharp corners of buildings, either
by bending them in fire, or, as was more commonly done, soldering
them together, or employing screws and other joints. But it was early
discovered that these junctions, when occurring at acute angles, were
bad conductors, occasioning sometimes the electric force to leave its
traced course, and fly off in some other direction. It is probable
that, in several well-authenticated instances in which this really did
happen, the joints were eaten away by oxidation, as in the case of
the chains; still, the effect of such occurrences was all the same.
The joining of strips of lead together was a far easier task than
that of handling iron in the same way, particularly for inexperienced
workmen, and thus the employment of the metal continued for some
time. However, it had to be abandoned gradually, on account of its
manifest disadvantages. Its extreme softness, which made it liable to
be broken by any accident, was one of them, and, still more so, its
want of conducting power--only about one-half that of iron. Thus leaden
conductors slowly went out of use, except in the form in which they
still act often to great advantage, that of water-pipes.

Among all the experiments made for producing the most perfect lightning
conductors, the one which created the greatest attention, some fifty
years ago, both on the Continent and in England, was the employment
of ropes made of brass wire. They were first recommended about the
year 1815 by a professor at the University of Munich, J. C. von Yelin,
distinguished for his researches into the nature of thunderstorms.
Through his influence most of the public edifices of Bavaria, more
particularly the churches, were provided with conductors of brass
ropes; and within a few years their employment became so popular,
owing to the ease with which they could be attached to all buildings,
that even the Roman Catholic clergy changed their attitude, and,
from being opposed to ‘heretical rods,’ advocated their extension in
every direction. But it was not long before the trust in brass ropes
as protectors against lightning was rudely shaken. Several instances
occurred in which buildings so protected were struck and damaged by
lightning, and at last there came a case which attracted the widest
attention, leading, on account of its supposed importance, to the
institution of a Royal Commission to report thereon. The little town
of Rosstall, in Franconia, Bavaria, had a church the steeple of which
was 156 feet high; and, standing on the brow of a hill, it overlooked
the country far and wide, visible for many miles. Necessarily much
exposed to the influence of lightning clouds, it had been provided
with one of the best brass-wire conductors, designed by Professor von
Yelin himself, and made of unusual thickness, being over an inch in
diameter. Nevertheless, on the evening of April 30, 1822, while a dark
storm-cloud, of extraordinary thickness, was passing over Rosstall, a
heavy flash of lightning was seen to fall vertically upon the church
steeple, followed by a terrible peal of thunder, which seemed to shake
the earth. When people looked up they beheld the church clock thrown
from its place, and part of a lower wall of the edifice thrown to the
ground. It was clear that the electric discharge from the atmosphere
had been one of unusual energy, but equally clear that the trusted
conductor had not done its work.

It was partly through scientific controversies about the relative
conducting value of metals, and partly through the action then
taken by several German Governments of providing all buildings with
lightning conductors, that the Rosstall case excited an extraordinary
interest at the time. The Royal Commission appointed by the King
of Bavaria, presided over by an eminent savant, Professor Kastner,
went to Rosstall to inspect the effects of the lightning discharge,
and Professor von Yelin did the same, as an independent, though not
disinterested witness. Their reports as to actual facts were the same.
The lightning, after striking the steeple of the church, had melted
the top of the ‘_Auffangstange_,’ or highest part of the conductor,
and further down had passed along the brass rope till coming to the
clock, only a few inches distance from it. Here the electric force had
evidently divided itself into several streams--the one exerting its
disastrous effects upon the clock and brickwork, and several metallic
objects underneath, and the other passing down the rope conductor,
but not without bending it, and, in one or two places, tearing it to
pieces. Such were the facts, visible to all eyes. But the conclusion
drawn therefrom differed widely. The members of the Royal Commission
made it public that the reason of the Rosstall lightning conductor not
having been efficient had simply arisen from its nature. Brass-wire
ropes, they declared, though perhaps useful against small discharges
of electricity, formed no reliable safeguards against powerful ones;
and they therefore strongly advised a return to the old-fashioned
iron rods. The conclusion was vehemently disputed by Professor von
Yelin. He admitted that it might be better, to provide for the proper
discharge of extraordinary masses of the electric force, to make his
brass ropes, when applied to high churches and other large edifices,
even thicker than they had been at Rosstall; but at the same time he
utterly denied that, even in this case, they had been the origin of the
disaster. He showed that the real cause of it was that the conductor
had not been laid deep enough into the ground, so as to touch moist
earth. The church stood upon sandy soil, on an eminence, and to touch
‘good earth’ the brass rope ought to have been sunk down to a depth of
at least fifty feet, whereas it did not reach one-third of that depth.
The professor was undoubtedly right, but his antagonists nevertheless
prevailed. A public prejudice, which no argument could overcome, set in
against brass-wire conductors, and they were pulled down from nearly
all buildings on which they had been laid, to be replaced by iron rods.
Some time had to elapse before real justice was done to metallic ropes
as lightning conductors.

With our present knowledge of electrical phenomena, and the practical
art of making conductors, it may safely be affirmed that the Munich
professor was right in recommending ropes, though not in approving
of brass as the best metal. In its very nature, brass, a compound,
can never be thoroughly reliable, because its conducting power varies
according to its composition. The facility with which it allows the
electric force to pass through it depends, in fact, entirely on
the amount of copper which brass contains, and is greater or less
accordingly, since the other metal entering into its composition,
zinc, has less than one-third the same conductivity. Now brass is, for
various purposes, made sometimes of 70 parts of copper and 30 parts of
zinc, and again, only equal amounts of both metals, setting calculation
as to its conducting power entirely at nought. But besides this, brass
has the great fault of being excessively liable to destruction by
atmospheric influences, and it was found, among others, in Germany,
that while brass ropes were used as lightning conductors, they were
frequently destroyed, in a comparatively short space of time, by the
action of smoke alone. It is true, the Continental mode, existing
both in France and Germany, of spanning conductors over the tops of
chimneys--illustrated in the engraving here as a warning ‘how _not_ to
do it’--had much to answer for this atmospheric deterioration, since
even tougher metals than brass could not be expected to stand the
constant action of smoke, often containing sulphurous fumes. But even
without such an evidently absurd arrangement as that of running any
conductors, whether in the form of ropes or cords, across the orifices
of chimneys, brass could never have answered all the requirements of
a lightning conductor. It was with justice that brass-wire ropes were
nearly altogether discarded some thirty or forty years ago, after
having had a short-lived reputation.

[Illustration]

That copper should not have been employed, long before brass and other
metals, in serving mainly for lightning conductors, its pre-eminence
for this purpose being undisputed, would seem a strange fact, were
it not explicable on several grounds. The first was the cost of
the metal, which, though varying in price, is seldom less than six
or seven times that of iron. It was needless for the advocates of
copper as conductors--and there were not a few from the time its
high conductive power had been demonstrated--to say that if copper
was six times as dear as iron, it was likewise six times better as a
carrier of the electric force, and that consequently the price, in
respect of applicability for lightning protection, was in reality the
same. But the reply to this was that copper, being one of the most
expensive metals, except the so-called ‘precious’ ones, was exposed
to the temptation of theft, and ought therefore not to be employed,
since it was possible that vagrants, or other people, might tear off
at any time the, in more than one sense, valuable pieces of metal
protecting buildings against destruction from lightning. The argument,
perhaps, was not worth much, but a better one not mentioned was in the
background. It was, till quite recent times, an achievement of the
greatest difficulty to manufacture long rods or bands of sufficiently
pure copper to serve as lightning conductors. Sir William Snow Harris
attempted, as already related, to get over this impediment by taking
short plates, and fastening them together, and over each other, by
copper nails. But this process, besides being enormously expensive,
was in many other respects unsatisfactory, notably in that it made a
shifting of the plates possible, and by the destruction of a few of
them ruined the whole system. The pith and substance of the whole was
the technical difficulty of hammering or drawing pure copper out into
great lengths. That it must be pure was essential, the fact being
thoroughly established that the electric conductivity of copper,
mixed with impurities such as arsenic, is often not two-thirds, and
sometimes not as much as one-half, that of the pure metal. This was
conclusively shown by Sir William Thomson in a series of researches,
and likewise by that distinguished investigator in the conductivity of
metals, Professor Matthiessen. The latter, while placing copper on the
same rank with silver, and far above gold--100 to 78--furnished the
following instructive list as to the relative value of different kinds
of copper:—

  Pure copper                    100·00
  Best American copper            92·57
  Australian copper               88·86
  Russian copper                  59·34
  Spanish ‘Rio Tinto’ copper      14·24

It will be seen that, according to the investigations of Professor
Matthiessen, admitted on all hands to be correct, the copper lowest
in the list, the ‘Rio Tinto,’ is barely equal to iron in electrical
conductivity, and, not having the hardness of the latter metal, would
be in every way inferior to it as a lightning protector. The employment
of the purest copper therefore became an essential point in the
manufacture of lightning conductors.

Fortunately, the difficulty was solved, at an earlier period than might
have been expected, by the demand for submarine cables. These had to
be made of wires of the highest possible electrical conductivity, and
the matter being one of high financial and commercial importance,
manufacturers soon began to use the utmost care in selecting ores
containing the smallest amount of metallic impurities. We believe
the lightning conductors now manufactured at the extensive works of
Mr. R. S. Newall, F.R.S., established at Gateshead on Tyne about
forty years ago, have generally a conductivity of 93 per cent. of
pure copper. It was laid down by one of the most eminent scientific
men of the day, not long ago, that the three principal qualities of
a good lightning conductor ought to be a maximum of conductivity, of
durability, and of flexibility that could be obtained, and there is
nothing coming up to this standard so well as ropes of pure copper.




CHAPTER X.

HÔTEL DE VILLE, BRUSSELS, AND WESTMINSTER PALACE.


The systems of lightning-conductors used for the protection of
the Hôtel de Ville and Westminster Palace seem worthy of separate
description, as showing the methods employed by Professor Melsens and
the late Sir William Snow Harris, both eminent authorities in their
respective countries. The two buildings are so entirely distinct in
their character, that it will be seen at once that very different
methods had to be employed in rendering them safe from the effects of
thunderstorms.

The Hôtel de Ville, Brussels, one of the finest Gothic structures
in the Netherlands, is fitted with an elaborate system of
lightning-conductors, erected under the superintendence of Professor
Melsens, a distinguished electrician and scientist. He has for many
years advocated the method of employing a great number of small
lightning-rods, in preference to one rod of large size, for the
protection of buildings from the effects of lightning; the main
characteristic of his system being that of covering the building with
a network of metal furnished with very many points, combined with
numerous and ample earth-contacts. This idea has been thoroughly worked
out at the Hôtel de Ville, Brussels; and probably no other building is
so completely guarded from the dangers of thunderstorms. The principal
feature of the Hôtel is a large central building, with a pinnacled
turret, from which rises a lofty spire, nearly three hundred feet high,
and adorned with four galleries, each with corner pinnacles. Upon the
top of this spire is a gilded colossal figure, seventeen feet high, of
St. Michael, holding a naked sword and standing upon a dragon. This
acts as a vane, and the point of the sword forms the highest terminal
conductor of the system. The main block of the Hôtel is ornamented with
six turrets, from each of which springs a small spire. In the rear is
a courtyard formed by buildings annexed to the front main block, and
composing the remaining three sides of this inner quadrangle.

The figure of St. Michael, all the parts of which are rivetted and
soldered together, rests on a pivot of iron, three and a half inches
in diameter, which is deeply embedded in the stone-work of the spire.
The weight of the vane produces a metallic connection with the pivot,
and the top of the platform in which the pivot is fixed is covered with
sheet-copper. Around this and in connection with the pivot are fixed
eight perpendicular galvanised iron conductors, two-fifths of an inch
in diameter, and provided with five points each. A flash of lightning
striking the statue would thus reach the pivot and then be divided
between the eight conductors. Just below the platform are placed, at
an angle of 45 degrees, eight large points six and a half feet long.
These are fastened to an iron band which encircles the spire, and are
connected with the eight conductors by means of a mass of zinc. Thus
the pivot of the statue, and consequently the statue itself, the eight
conductors, the eight large points, and the forty small points on the
conductors, constitute a protection which dominates the edifice, and
represents a circular space of about five and a half yards in diameter;
that is, between the extremities of the large points which project from
under the platform. In this manner a flash of lightning is instantly
distributed and conveyed by the conductors to the ground. It may be
mentioned here that a thin copper wire, insulated by three coatings, is
fixed on the north side of the iron band in which the large points are
fastened; the other end of this wire is left free, and can be utilised
as a conductor for a rheometer or any other electric machine which it
might be thought proper to use permanently for the registration of
lightning striking the conductors.

The eight conductors have each an unbroken continuity of about 310
feet; and they collectively show a continuous section of nearly
one inch--almost half as much again as the limit of safety given
in the ‘Instruction’ of the Paris Academy. Although, in Professor
Melsen’s opinion, rods of somewhat less diameter would have been
amply sufficient for security, he chose the largest size which could
be easily bent to the varying contours of the building, and also
as allowing for the expansion and contraction caused by changes of
temperature. If conductors of only one quarter of an inch diameter
had been used they would, it is true, have shown a total section
just above the limit of the ‘Instruction;’ but, since Coulomb has
demonstrated that tensional electricity is more particularly carried on
the surface of bodies, M. Melsens thinks it is necessary to consider
the action that this surface might exercise in the easy transmission
of electricity. Some old German writers on this subject went so far
as to assert that the conductivity was proportioned to this surface.
They therefore recommended flat bands or hollow tubes in place of rods.
Although exact figures cannot be given as to the effect due to the area
of the surface, M. Melsens considers that it is unquestionable that
the relation of the section to the surface has a marked and definite,
although at present unknown, result. In the case of the Hôtel de Ville,
Brussels, he thinks the eight conductors possess a signal advantage
over one conductor, even though it had a larger section--say one inch.
Experience will doubtless teach how to determine more precisely the
extent of this surface-action.

The eight conductors descend the length of the octagon of the spire
until they reach the first gallery; going round this they pass over
the balustrade, and then converge towards each other; are carried
over a prominence in the roof; and as they pass along gather up
other conductors of similar size from the ridges and parapets of the
buildings which form the quadrangle. Projecting vertically from these
horizontal lengths of the conductors are a large number of points and
aigrettes. The summits of the lower tower are also furnished with a
great many points. These eight main conductors are then taken down the
wall of the building into the courtyard, and at about three feet from
the ground are carried into a box constructed of galvanised iron, and
in it are connected into one solid mass by zinc, which has been poured
molten into the box. Almost throughout their length the conductors are
left loose, so as to remove all complication arising from dilatation;
the play of this dilatation being rendered easy on account of the small
section of the conductors, which bend readily.

In accounts of lightning striking buildings which have been provided
with lightning-conductors, it is almost invariably found that these
conductors are incomplete, and have generally been fixed by persons
ignorant of the scientific questions involved. When the facts in
such cases are carefully examined it is found, as a rule, that the
defect is in the connection with the water underground, or in the
bad conductivity of the earth in which the conductors terminate.
In establishing a perfect communication with the earth, M. Melsens
considers it is necessary, not only to place the conductors in contact
with water, but also to see that the contact extends over a large
surface. The Paris Academy ‘Instruction’ recommends this precaution,
but in a very vague and too succinct a manner. To the above rule may
be added another condition, namely, that the earth-connection should
be large in proportion as the site of the building is redundant in
metal products in direct or indirect contact with the ground, the
subsoil, or the damp earth of the foundations, and sometimes even with
water itself. With regard to the metal contained in the materials of
buildings, it is not sufficient to establish a connection at one point
only, as is generally supposed. On the contrary, it is important that
all the metal-work should be connected with the conductor at least at
two points, in order to realise closed metallic circuits, and thus
offer an entry and exit, or a free metallic course, for the current of
electricity. The foregoing statements have been placed here chiefly
because the principles they convey have been so rigidly, and at the
same time successfully, carried out by Professor Melsens at the Hôtel
de Ville, Brussels.

[Illustration: Fig. 3.]

To return to the eight conductors and the earth-connections provided
for them. It has been shown that these conductors, after descending
the wall of the building, reach a point about three feet from the
ground, where they are embedded in a rectangular box of galvanised
iron, which is eight inches long, three inches broad, and three and a
half inches high. In the bottom of the box are three holes, through
which pass three series of eight conductors, each series being of the
same diameter as those which descend from above; the conductivity
being thus increased threefold. All of these are formed into one mass
by the zinc, which has been poured into the box in a molten state,
so that they constitute with the eight rods from above, one integral
conducting system. In the illustration which is here given the box
is represented by B, and the eight main conductors coming down from
the building by C C. The three series of rods numbered 1, 2, 3 show
the triplicated conductors issuing from the box. The first series is
placed in communication with the water by means of an iron pipe, which
carries it underground to a well. Here the rods are inserted in a large
tube six and a half feet long and nearly two feet in diameter (see
engraving). This tube is let down almost four feet below the level
of the earth, and sustained by two chains hung on two iron holdfasts
fixed in the side. The conductors C C are fastened to this tube in the
following manner:--A small length of straight iron cylinder is placed
outside the flange of the tube; and the ends of the conductors being
arranged between the cylinder and the flange, the space _a a_ is filled
with molten zinc; thus rendering the substance of the iron tube and
that of the conductors metallically continuous. The well into which the
tube is sunk furnishes perpetually a contact of eleven square yards
between the water and the iron of the tube. Into the space _a a_ is
also introduced a large number of small galvanised iron wires to act
as auxiliary conductors; these are terminated by being brought to a
point and soldered to the mass of zinc. In order to prevent as far as
possible the formation of rust, a large quantity of lime is thrown into
the well, in order to make the water alkaline. The second series of
conductors, painted with coal-tar, is placed in a covered metal gutter
and carried some distance to a gas-main in a spot where the earth is
moist. The conductors are fixed by means of a large copper plate, which
is soldered to the gas-pipe or main. On the copper plate are fastened
sixteen large-headed brass screws, to which the conductors are secured.
This arrangement is enclosed in brickwork, the wires being painted with
coal-tar; and a quantity of boiling tar is poured on the copper plate,
over which is laid a cloth, thus preserving the whole from oxidation.
The third series of conductors is carried in a gutter, similar to that
which contains the second series, to a water-pipe in the Place de
l’Hôtel de Ville, and the wires are fixed to it in the same way.

[Illustration: Fig. 4.]

It may be added that the whole of the conductors above-ground--with the
exception of the points--are painted with oil.

Although it is correct that the coke generally placed around the
earth-connection of conductors aids by its good conductivity to bring
them in contact with a large surface of earth, Professor Melsens has
preferred to employ tar, which, it is true, is insulating, but helps
materially to preserve the conductors. It is estimated that the entire
contact between the earth and the underground surface of iron is about
300,000 square yards.

Professor Melsens thinks it is worthy of note that, although copper
is a better conductor of electricity than iron, it has less molecular
strength. Where thin iron wire would simply be beaded--without losing
its conductivity--by an exceptionally strong charge of electricity,
copper wire of the same thickness would by a similar charge be
dissipated to a black powder. Professor Melsens has verified this
in some very interesting experiments. The large use of iron in his
system of conductors on the Hôtel de Ville, Brussels, was rendered
imperative by reason of the enormous cost of sufficient copper for such
an extensive system. But Professor Melsen’s experiments, nevertheless,
give some support to the selection of iron for large and complete works
of this kind.

Sir William Snow Harris, in his arrangements for the protection of
the Palace of Westminster from lightning, has endeavoured to perfect
the general conductivity of the whole mass of the building, and so
make it assume the same relation to the electric discharge as if it
were a complete mass of metal. Westminster Palace differs in one
important respect from the Brussels Hôtel de Ville--the general level
of the roofs is covered with iron coated with zinc, and in many places
directly connected with the earth by cast-iron water-pipes. The roofing
thus constitutes, although imperfectly, and only to a limited extent,
a protection of itself. Sir William Snow Harris had, therefore,
chiefly to provide for those portions of the building which are above
the general level of the roofs, and, by the use of ample conductors
of copper, to make up for the comparatively low conductivity of the
roofing and the iron pipes which connect it with the earth.

From the terminal which forms the highest point of the large central
tower is brought a copper tube of two inches diameter and one-eighth
of an inch in thickness, the joints of which are secured by solid
screw-plugs and coupling-pieces. This tube is carried down in the
south-west angle of the tower and fastened to the masonry by metallic
staples. At the junction of the tower with the roofs the tubing is, or
at any rate was, thoroughly connected with the metal of the roof, and
then continued to the earth in as straight a course as practicable,
and there terminates in two projecting branches made of solid copper
rod. By carrying this copper tubing direct to the earth, instead of
terminating it in the metal-work of the roof, the electrical discharge
obtains a conducting medium of the same power throughout, in place of
having to leave a high power for one of lower conductivity.

The Victoria and Clock Towers, which are each 300 feet high, are both
fitted with a copper band, five inches wide and a quarter of an inch
thick. These run down the walls, and are connected with the metal of
the roof, and also with the metallic rail of the staircase within each
tower. The ornamental turrets and pinnacles of St. Stephen’s Porch
are protected by small bands of sheet-copper, two inches wide and
one-eighth of an inch thick; these are also placed in connection with
the metal of the roof.

The north and south towers of the central block, and the north and
south wing towers of the front facing the Thames, have attached to
them bands of sheet-copper running from their respective vanes to the
roofing below. The bands are connected with the metal of the roof, and
are then carried down independently to the earth, in a similar manner
to that adopted on the large central tower.

The only other prominent portion of the edifice is the ventilating
shaft of the House of Commons, where, during the sitting of Parliament,
a coke-fire is generally burning, and from which, therefore, a stream
of warm and rarefied air is constantly being emitted. The conductivity
of an ascending column of warm vapour is known to be great, and
accidents from this cause are of frequent occurrence, although very
often they are not ascribed to their true source. To obviate this
danger, the ventilating shaft is provided with a copper tube conductor,
fixed on its eastern side, and connected with the metal of the roof.

This short description of the measures adopted by Sir William Snow
Harris for the protection of Westminster Palace contains all the
salient points of the system which at that time, some twenty years
ago, was doubtless the best that could be devised. But, although
nearly 4,000_l._ was spent upon this work, from that time to this, as
far as can be ascertained, these lightning-conductors have never been
tested! It is therefore very possible, and indeed probable, that on the
occurrence of any very heavy thunderstorm they would be found wanting,
and considerable damage would ensue, the extent of which no one can
estimate.

[Illustration]




CHAPTER XI.

WEATHERCOCKS.


Although such an opinion seems scarcely orthodox, it may, and not
unreasonably, be doubted whether weathercocks are of any great use in
demonstrating the direction of the wind. The under-currents of air are
so numerous and so conflicting--especially in towns where the houses
are lofty--that it is quite possible for two weathercocks at different
ends of the same street to show at the same moment the wind blowing
from opposite directions. However, the prevailing custom of placing
these ornaments, in connection with lightning conductors, on the
highest points of large buildings renders necessary some explanation of
the manner in which they should be fixed; for if they are improperly or
negligently attached to the lightning conductor, the continuity of the
latter may be rendered defective, or at least seriously impaired.

The two main points to be kept in view are, that the weathercock should
move freely with the wind, and that the continuity of the lightning
conductor should be preserved. One method of obtaining this result is
to put the weathercock into a circle, with the terminal rod of the
lightning conductor on the top. This is called the ‘nimbus cock,’ and
is in somewhat doubtful taste. The continuity, however, is perfect, and
the cock, which is simply placed on to a point, moves easily with the
wind. An example of this cock may be seen erected on the central finial
of the Cathedral at Amiens.

[Illustration: Fig. 5.]

A different way is to make the terminal rod of the conductor serve as
a pivot for the cock, as shown in fig. 5. This is the usual kind of
weathercock used in England, and is considered by many to be one of the
best forms. It is arranged in this manner: the actual terminal of the
conductor ends with a rounded or sharp point of steel, and acts as a
spindle, on which the weathercock revolves. It varies in diameter from
five-eighths to three-quarters of an inch. A tube, from seven-eighths
of an inch to one inch in diameter, and on which is fixed the cock, is
made to fit on to this terminal or spindle. This tube contains at the
extremity of its interior a piece of steel or glass, or sometimes a
glass ball, and being lengthened to a point, with a platinum or copper
tip, serves as the point of the lightning conductor. This weathercock
is generally called a ‘formed cock;’ it measures at its extreme length
about twenty-one inches, and weighs about twelve pounds. It will be
seen that in this method there is nowhere absolute contact between the
point and the pivot; consequently electric sparks must be caused by
the current of electricity. Besides this defect, if the metal becomes
oxidised between the surfaces, insulation will be the result. This
plan, though often adopted, sacrifices the principal for the sake of
the accessory.

[Illustration: Fig. 6.]

Fig. 6 shows another method of fixing the weathercock on to the
conductor. It is called a ‘solid cock,’ and is cut out of sheet-copper
one-sixteenth of an inch thick; it revolves on a spindle in the manner
shown in the engraving. This spindle, on which the cock or ‘blade’
works, differs in diameter according to the weight of the bird, the
height and style of the building, &c., but as a rule it is from
five-eighths to three-quarters of an inch in diameter.

It is usually used for Gothic buildings and private mansions, but
should not be adopted, as it is apt to be lifted off its spindle by
the wind. When a down-current of wind takes place there is generally
an up-current at the same time, and there is a possibility of the cock
being blown off during a gale. If it is used it should have a long
point fixed above it.

[Illustration: Fig. 7.]

A better arrangement than either of the two preceding ones is to let
the point go quite through the weathercock in an encasement. The
cock is then supported on a small round embasement, upon which are
placed three small rollers (see fig. 7); on these the vane revolves
easily, the continuity of the lightning conductor is perfect, and
the weathercock freely turns round on the point so long as the small
rollers are in order. In this arrangement, as in most others, the best
material for the point is copper. Steel has occasionally been used, but
it was found that in a very short time the rust had so eaten into the
joints that the cock would not turn with the wind.

The most complete and enduring method is that indicated in figs. 8 and
9; this is the plan adopted in England for all the best work. By this
arrangement, the friction being very much diminished, the weathercock
revolves with great ease and freedom; the possibility of its getting
out of order is reduced to a minimum; and the continuity of the
lightning conductor remains unimpaired.

[Illustration: Fig. 8.]

[Illustration: Fig. 9.]

It is accomplished in this way:--A circular plate, through the centre
of which the point passes, is permanently fixed some distance down
the point. On this circular basement rest three glass balls, rolling
on three axes radiating from the centre, i.e. the point, and fixed in
their outward extremities to a ring which surrounds the balls (see
fig. 9). On these balls is placed another circular plate, on which is
fixed the weathercock. The weathercock and circular plate, with a hole
through the centre, is simply put on to the point of the conductor, and
allowed to rest loosely of its own weight on the balls of glass.




CHAPTER XII.

LIGHTNING PROTECTION IN FRANCE AND AMERICA.


In this chapter it is proposed to give a brief _résumé_ of the
different systems of constructing, erecting, and repairing lightning
conductors in France and America. The laws of electricity being the
same all the world over, the methods employed in these countries are
necessarily similar in their essential principles; nevertheless they
vary somewhat in detail, both from each other and from the work of the
best firms in England.

Until a very few years ago the lightning conductors throughout France,
although many in number, were in a very neglected state. Badly
constructed in many cases, their original faults had grown worse
from want of attention. The connection of the terminal rod with the
conductor was generally made by means of a strap or iron collar, which,
after a short time, rusted to such an extent that the continuity was
practically reduced to nothing, and the conductor, so far from being a
protection to the building, was a positive danger to it.

Latterly, however, a reaction has taken place, and a more careful
method of connecting the various joints of the conductor has been
contrived, or rather, revived, and a better system of periodical
inspection and testing is carried out.

[Illustration: Fig. 10.]

[Illustration: Fig. 11.]

Under the French system, what is called in England a lightning
conductor, and to which the French give the name _Paratonnerre_, is
nominally divided into three parts: the terminal rod, the conductor,
and the _racine_, or root, i.e. the earth connection. With regard to
the terminal rod, the ‘area of protection’ theory is, in France at any
rate, still believed in by a great many people. In that country, as
a rule, it is made of wrought iron in a single length, and polygonal
or slightly conical; its height depends upon the size and area of
the building it protects, the general presumption being that, under
ordinary circumstances, a terminal rod will protect effectually a cone
of revolution, of which the apex is the point of the rod, and the
radius of the base a distance equal to the height of the said rod above
the ridge, multiplied by 1·75. Thus a rod rising eight yards above the
ridge of a building would effectually protect a cone-shaped space, the
base of which, at the level of the ridge, has a radius of 8 × 1·75 =
14 yards. In actual practice somewhat wider limits are allowed. The
height of the terminal rod having been determined according to the
circumstances under which it is erected, it is then galvanised with
zinc in order to prevent oxidation, and the connection between the
terminal rod and the conductor is formed by means of the following
arrangement. A little above the base of the terminal rod, say about
eight inches from the roof of the building, a flange A (see fig. 10) is
welded with a hole pierced through it. Through this hole the conductor,
previously filed down to the proper dimensions, must be tightly passed.
After scraping the iron around the hole, a washer of lead is placed at
P and P´ (see fig. 11), and the button B, by means of a strong layer of
solder, thoroughly binds everything together. In this way an excellent
joint is obtained; the contact surface is considerable, and, if the
work is carefully done, the joint is completely preserved from rust.

[Illustration: Fig. 12.]

The point of the terminal rod, although sometimes made of platinum,
generally consists of either pure red copper, or, what is considered
still better, an alloy of 835 parts silver and 165 parts copper. It is
fastened to the terminal rod in the manner shown in fig. 12.

C is the trunk of a red copper cone, upon the top of which a point, P,
made either of platinum or of an alloy of silver and copper, as before
mentioned, is screwed, pinned, and strongly soldered with pewter solder
at _a_, the whole being screwed on to T at _b_. To ensure complete
contact and continuity, a washer of freshly-scraped lead is inserted
between C and T, and the whole of the joint thickly covered with a
layer of pewter solder. It may be added that the point forms an angle
of fifteen degrees with the vertical, consequently the point terminates
in an angle of thirty degrees.

[Illustration: Fig. 13.]

For the conductor of the ‘paratonnerre’ lengths of iron bars are
principally used; formerly these were jointed together by means of a
pyramidal bolt let into a notch of the same form, and connected by
a simple iron pin. This method, however, was discovered to be very
bad, as it failed to preserve the continuity of the conductor after
it had been erected a little time. The following plan, as represented
in fig. 13, is now used for the best work, as being more durable and
affording a better contact. On each side of the bars to be joined, two
flanges, about six inches long, and half the thickness of the bars,
are filed out. A thin piece of carefully-prepared lead is then placed
between them. The whole is then firmly fastened together by bolts at B
and B and completely covered with pewter solder, and thus furnishes a
solid, durable contact which possesses very small resistance.

Formerly the conductors were, at regular intervals, rivetted to
cramps let into the wall for the purpose of retaining the conductor
in its place. As this plan left no room for the play of expansion and
contraction caused by variations in the temperature, it was found that
at times the conductor was very much strained and even bent by reason
of this expansion and contraction. To avoid this evil an apparatus,
which has been approved by the Paris Academy of Sciences, has been
substituted for the cramps and rivets. This apparatus consists of a
fork in which the conductor is held fast by a pin (see fig. 14). Being
able to move backwards and forwards in the fork with great facility,
the conductor is thereby permitted to expand or contract under the
influence of temperature without threatening its supports with
destruction.

[Illustration: Fig. 14.]

The question however arises, upon what part of the paratonnerre ought
the effect of such contraction or expansion to be borne? The Paris
Academy of Sciences has sanctioned and recommended the use of a
compensator, which is designed to bear this strain. This compensator,
which is now much used in France, may be seen in fig. 15. It is
composed of an elastic plate F, made of well-annealed red copper,
three-quarters of an inch wide, at least twenty-eight inches long, and
about a quarter of an inch thick. The two extremities of this plate
are firmly fastened to the two ends of two lengths of the conductor
by the bolts and counterpieces B B´, and afterwards covered with a
thick coating of pewter solder. When, in consequence of the heat, the
conductor expands, the curve of the copper plate F will become greater,
and in cold weather it will become less. As a rule, a single apparatus
is supposed to compensate for the effects produced by long straight
lengths, and it is therefore thought sufficient to place one at each
bend.

With the exception of the terminal rod, it is the rule in France to
cover the whole of the paratonnerre with some coating in order to
preserve it from contact with the air. This is attained by covering it
with either a strong coat of tar, or a painting of a metallic basis,
such as zinc or tin filings.

[Illustration: Fig. 15.]

In larger buildings what is termed a ‘ridge-circuit’ is often used. It
consists of an unbroken metallic connection running along the ridges
of the building to be protected, and connected with the conductors
and terminal rods, and consequently with the subterraneous sheet of
water which forms the common reservoir. It is made of lengths of
square iron bars or rods having a thickness of about three quarters
of an inch square, and fastened together by overlaying the ends,
bolting them together with two bolts, and covering them well with
solder in the manner shown in fig. 13. New branches are formed by
T-shaped connections, the cross-piece of the T overlaying the original
ridge-circuit, and the stem making the first length of the new branch.
In some cases the ridge-circuit rests directly on the ridge of the
roof; but in order to avoid injury during the repairs to the roof or in
other ways, the plan adopted in good work is to raise it some distance
above the ridge on supports at suitable distances, and thus prevent the
possibility of damaging the joints and solderings.

The form and arrangement of these supports depend on the nature of the
roof. Sometimes forked uprights are used--these allow for the expansion
and contraction due to changes of temperature; in other cases simple
cast-iron bearings, weighing from ten to twelve pounds each, are laid
upon the ridge, their upper surfaces being grooved to receive the bars
of the ridge-circuit.

All masses of metal used in the construction of the building are
metallically connected with the paratonnerre. As a rule, this is
done by pieces of iron about half an inch square, which are strongly
soldered to the metal surfaces, and then connected with some part of
the conductor or ridge-circuit.

Although in France, as elsewhere, all experts are agreed as to the
prime importance of the disposition and arrangement of the _racine_ or
earth-end of the paratonnerre, a difference of opinion prevails as to
the best means of insuring a good earth-contact, and many methods have
been tried, all of them similar in principle, but differing somewhat in
application. It is proposed to give here a brief outline of the best
contrivances employed for this purpose.

One main object, in arranging the earth terminal of a lightning
conductor, is to avoid the gradual destruction of the _racine_ by
the action of alternate dryness and moisture which, unless the iron
is protected in some way, corrodes, and eventually eats it entirely
through. There are several ways of remedying this evil. In France it
is common to find used for this purpose a vertical spout of tarred,
boucherised, or creosoted wood, rising a few inches above the soil.
Some authorities recommend the simple plan of covering this part of
the conductor with a strong coating of tar, others covering it with
a wrapper of sheet lead, and this last method is probably the best.
With regard to the extreme end of the conductor, the system approved
of by the Paris Academy of Sciences is generally used in good work.
This system is the use of a trough filled with broken charcoal, through
which the conductor runs; charcoal preventing the too rapid oxidation
of the iron. For charcoal, coke may be substituted. The trough (see
fig. 16) is made either of wood, gutter tiles, or ordinary bricks
without mortar, so as to allow the moisture of the soil to permeate
through. It is preferable, even at the expense of lengthening the
conductor, to carry it through the lowest and dampest plots of ground
around the building.

[Illustration: Fig. 16.]

To obtain a perfect contact between the end of the conductor and the
earth, or common reservoir, the French use several methods. One of
the earliest ones was the multiplication of the iron bars attached to
the end of the conductor, and inserting them for some distance into
well-water. Theoretically this arrangement is good, but it has been
found that the decay of these terminals by the action of rust was
so rapid that, unless they were carefully watched and periodically
repaired, they soon became insufficient, if not useless. In addition
to this, it is the opinion of many French savants that a mere water
contact is not enough, a soil that is always moist being in their
judgment far preferable. The simplest plan adopted for attaining this
end is that of inserting into the moist ground to a certain depth,
regulated by the nature of the soil, one or several metallic branching
stems, which are connected with the conductor. By another arrangement,
invented by M. Callard, the conductor is terminated by a kind of
galvanised iron grapnel, placed in a wicker basket filled with pieces
of coke. Where the soil is dry, and moist ground cannot easily be got
at, the harrow or grating shown in fig. 17 is often used. It is placed
between two layers of horn embers, or charcoal, and sunk as deeply
as it conveniently can be, the end of the conductor being carefully
connected with it by soldering or by a quantity of melted zinc.

In towns, the water-pipes and gas-mains, possessing as they do,
large metallic surfaces, are generally utilised for making the
‘earth-contact.’

[Illustration: Fig. 17.]

Sometimes, instead of iron bars, galvanised iron cables of about an
inch in diameter are used for the conductors of paratonnerre, and
occasionally red copper cables of half-an-inch only in diameter, but
the use of these latter is uncommon.

[Illustration: Fig. 18.]

Fig. 18 exhibits a modification of the point of the terminal rod which
is advocated by M. R. F. Michel. The arrangement is based on the
principle that, on the approach of a tempest cloud, the more points
there are, the greater will be the neutralising effect. M. Michel
considers that when a terminal rod has only one point, it acts only
in one direction; but if there is a large number of points branching
in all directions, the preventive action is materially increased; he
therefore proposes the use of this contrivance, which is carried out
by having the ordinary conical trunk copper point on the top of the
terminal rod melted down, and moulded so that it presents in its middle
a circular swelling. Into this swelling arrows are fixed, inclined at
each side of the horizontal plane to an angle of 45 degrees, as shown
in the engraving. These arrows radiating in all directions are supposed
to ‘hasten the neutralisation of the electrified cloud; and in the
event of a discharge, the discharge, by dividing amongst them, will
prevent their fusion.’

Before quitting the French system, mention should be made of a novel
form of lightning conductor devised by M. Jarriant. This gentleman
proceeds on the hypothesis that the most essential requisites of a
lightning conductor are:--a terminal rod metallically homogeneous,
which should rise to a good height; that it be sufficiently light
to avoid damage to the roof, and yet be strong enough to resist the
violence of the wind. To attain these requirements, M. Jarriant secures
his conductor with three or four stays, which are firmly fixed to the
roof and converge to the top of the terminal rod, to which is fastened
the ordinary copper point, recommended in the ‘Instruction’ of the
Academy of Sciences. Iron supports are placed at different heights in
order to ensure the perfect solidity of the system. Galvanised iron
is employed, and all the various stays and supports are metallically
connected with each other. The angles of the irons are all acute,
and placed so as to offer the least resistance to the wind. The
advantages claimed for this method are that the upper part of the
conductor bristles with spikes and aigrettes, which he considers a
great advantage in regard to the preventive effect produced by the
conductor; it allows of the conductor being raised much higher above
the building; it presents a large surface to the electrified cloud; the
joints are so arranged that they cannot be dislocated by the expansion
and contraction caused by variations of temperature; and, lastly, it is
affirmed that these conductors cost thirty per cent. less than those
erected under the ordinary system.

America stands pre-eminent above other countries in the numerous and
extraordinary schemes that have there been promulgated in regard to the
protection of buildings from the effects of lightning, and probably
no other nation has been so systematically victimised and swindled in
this matter. The tramping ‘lightning-rod men’ of the United States are
notorious for extortion and ignorance: they use all kinds of fantastic
and peculiar shaped terminal rods and conductors, the main object
being to make as great a show with as little metal as possible. Their
work is almost entirely confined to the upper portion of the conductor,
to the neglect of the most important part--the earth terminal. In
consequence, the majority of the lightning conductors in America are
untrustworthy; very often they are practically insulated from the
‘common reservoir’ or subterraneous water, and are therefore more often
a source of danger than a protection. Unhappily, these peripatetic
mechanics are by no means extinct, although increased knowledge is
gradually driving them from the field.

In America, a strong point is made of utilising, as far as possible,
all the existing natural conductors that are to be found upon a
building, such as gutters, rain-pipes, and other metal surfaces. During
a tempest, the opposite electricities of the earth and the air often
select, by their inductive influence, a rain-pipe, gutter, metal roof,
&c., for the passage of an electric discharge between them, and unless
these metallic surfaces are connected with the earth, they are apt to
be dangerous. But if they are properly connected together, and provided
with a good earth-contact, they materially assist to diminish the
intensity of a discharge.

In the case of a building with a roof of slate, wood, or other material
of low conductivity, a conductor made of either bar iron or stranded
cable is placed along the ridge and gable ends, and carefully connected
with the gutters and rain-pipes; where the rain-pipes are less than
three inches in diameter, the bar or cable conductor is often extended
from the roof down the side of the building, and connected with the
earth terminal. When this is done, the bar or cable conductor is placed
between the rain-pipe and the wall of the building, or at any rate
close to the rain-pipe, and connected with it by solder or bolts.

All metallic chimney caps, cornices and railings on the tops of
buildings, as well as the water-pipes, gas-pipes, hot water-pipes,
and other large or long pieces of metal, whether they occur inside or
outside the building, are connected with each other by a conductor
composed of light stranded wires, each about three-sixteenths of an
inch in diameter; they are also connected with the main conductor
at its nearest point. Where several adjacent buildings have each
a metallic roof, these roofs are connected together by means of a
horizontal conductor.

The terminal rod of the conductor generally projects about four feet
above the chimney or other highest point of the building. It consists
of a round iron rod seven-sixteenths of an inch in diameter, the lower
extremity being hammered out for the purpose of fastening it to the
conductor by soldering and screws or by bolts. A small building, not
exceeding twenty-five feet in length or breadth, is generally fitted
with either one terminal rod placed on the centre of the ridge of the
roof, or with two rods, one at each end of the ridge, the latter method
being the preferable one. In larger buildings terminal rods are placed
at intervals of about twenty feet along the roof. The upper end of
the rod is sometimes pointed, but not always, the argument being that
although the ordinary end of a rod is blunt when used in connection
with a Leyden jar, but that when applied to a thunder-cloud, which
extends over thousands of acres, it becomes pointed, and bears the
same proportion to a thunder-cloud as the sharp point of a needle does
to the hand of a man. Occasionally the point is tipped with platinum,
gold, silver, or pure copper, in order to prevent oxidation, but this
is not considered essential, it being presumed that, practically no
amount of rust on the top would impair the efficacy of the terminal rod.

In the case of a building having a flag-staff upon it, a galvanised
iron wire is fastened along it and projects about six inches above the
top, the lower end of the wire being of course carefully soldered or
otherwise connected with the main conductor.

Steeples and spires, in addition to the ordinary vertical conductor,
are fitted with horizontal conductors placed around them at intervals
of about twenty feet, and connected with the vertical conductor. This
is to provide against the occasional discharges that take place in
the centre of steeples, and which are caused by the deflection of the
discharge in the air by the rain.

Chimneys and air shafts, from which heated air or smoke escapes,
are fitted with metallic caps which are connected with the general
conductor. In order to protect this metallic cap from the effects
of the sulphurous fumes arising from the chimney, a terra-cotta cap
is contrived to fit inside the metallic cap. An analogous method is
adopted with regard to the ventilators of barns and ice-houses. If
these buildings have the ordinary ventilators in the form of dormer
windows upon the roof, an iron rod seven-sixteenths of an inch in
diameter is placed vertically across, and above the centre of the
opening of each ventilator, and connected with the conductor. Should
the barn or ice-house have openings or doors through which warm vapour
can escape, a conductor is fixed to the roof at the gable ends above
the centre of each opening or door, and extended outwards about five
feet, at an angle of forty-five degrees from the roof, so as to be in
line with any ascending vapour, or any descending charge of electricity
following the course of the vapour. All these auxiliary conductors and
terminal rods are metallically connected with the main conductor of the
building.

The conductors are simply fastened to the building by iron staples or
by straps of sheet iron, pierced with two holes for nails or screws.

In America, as elsewhere, the earth-terminal is regarded as of prime
importance, and in all properly constructed lightning conductors
receives the greatest care and attention. In the first place, such
metal pipes as lead from the building to the water-mains, gas-mains,
and sewers are carefully connected with the principal lightning
conductor, in order that they may act as auxiliary earth-terminals.
For the principal earth-terminal many contrivances have been brought
forward, but very few possess any originality, and many are positively
useless. Some of the best are similar to those in use in England;
among others, perhaps the best method is that of placing a cast or
wrought-iron pipe of three inches inside diameter, and about ten feet
long, vertically in thoroughly moist earth and carefully connecting the
conductor, or conductors, with it. The chief objections to this plan
are the occasional difficulty of getting a moist earth at all, and the
possibility of earth that is generally moist getting dried up in hot
weather. To obviate these risks, the following arrangement is used:—

In a pipe of wrought or cast iron, at least ten feet long, and having
an inside diameter of two inches with a thickness of three-eighths of
an inch, are made a number of longitudinal openings or perforations,
about ten inches long and a quarter of an inch wide. These openings
or perforations are made at intervals of ten inches, and are placed
in one or two lines opposite to each other. If it is preferred, round
holes of from half an inch to one inch in diameter, and about six
inches distant from each other, may be substituted for the longitudinal
openings. This perforated pipe is placed in an upright position in the
earth, and is so situated that it receives at its top opening the waste
or rain water flowing along a channel or drain constructed for that
purpose. The water, after running into the top of the pipe, gradually
percolates down, and passing through the perforations or openings into
the earth around and underneath the pipe, moistens it to such an extent
and at such a depth as to render it but little affected by the heat of
the sun. The pipe is generally placed at some little distance from the
building, so as to give a sufficient area of earth to be kept moistened
and to prevent the walls of the building being affected by the damp.

Occasionally, the pipe is made triangular or square, and with
perforated branches and other metallic conductors. It is also sometimes
constructed with enlargements at the top or bottom, so as to hold more
water. Probably, however, the simplest plan is the best, as--if the
soil be suitable--a plain round wrought-iron pipe can be driven into
the earth. If a cast-iron pipe is used, a hole of a convenient size is
excavated for it. In this case, great care has to be taken that the
earth is thoroughly well rammed down all round the pipe.

Another arrangement is to employ, instead of a cast or wrought-iron
pipe, a number of round or flat-iron bars, fastened together at the top
and bottom by rivetting to metal hoops in such a manner that intervals
are left between each bar, through which the water can pass. Sometimes
a solid pipe without the openings is used, but it is not found to be
so satisfactory as the perforated pipe, because the latter allows a
greater amount of water to pass through it into the soil, thereby
furnishing a larger area of moist earth.

The French method of carrying the conductor to the bottom of a
neighbouring well is frequently adopted where it is practicable, and
the water of the well is not required for drinking or cooking purposes.

A few words may be added here on the method of protecting the large
mineral oil tanks which are to be found in the United States. Many of
these oil tanks are of very large capacity, some of them containing a
million gallons of oil. They are generally constructed of thick iron
plates rivetted together. The roofs are usually made of wood coated
with tar, but in some cases iron is adopted. As a rule, several of the
tanks are grouped together and connected with each other--and in some
instances with distilleries--by means of subterraneous iron pipes.

One method of protecting these tanks is to erect around them, at
a distance of some ten feet, wooden supports, on which are placed
upright metallic conductors which overlook the tank, and are connected
with each other near their tops by stout iron wires, thus forming a
network of conductor which is supposed to intercept any discharge of
electricity from a tempest-cloud, and prevent it from reaching the oil
tank. This method, however, has failed in several notorious instances,
and is not countenanced by the best authorities.

A better and less complex arrangement is now usually adopted by the
best firms. The chief object of this arrangement is to prevent the
temperature of the oil tank, and of the atmosphere above and around it,
being raised by means of an electric discharge. This is accomplished
by using large conductors, which are carried some distance above the
oil tank. These conductors, of which there should be at least four,
are formed of flat iron bars about one and a half inches wide and
half an inch thick; they are securely fastened to the sides of the
tank at equal distances from each other, and metallically connected
with it. About thirty feet above the roof of the tank they meet, and
are carefully and substantially joined together, and supported, if
necessary, by a wooden post extending from the centre of the roof of
the oil tank.

The earth terminals, of which there must be one to every two
conductors, consist of perforated iron pipes, as before described,
three inches in diameter and fifteen feet long. They are sunk into
thoroughly moist earth, and metallically connected with the lower part
of the tank. These perforated pipes are so arranged that they catch the
rain water from the roof of the tank; by this means the surrounding
earth is kept moist. It may be mentioned that by utilising the tank
as a portion of the system of conductors, the electric discharge is
distributed and much weakened.




CHAPTER XIII.

LIGHTNING PROTECTION IN ENGLAND.


In its essence there cannot be anything more elementary than the theory
of protection against lightning. It is simply to lay a metallic line
from the top of a building, or other object to be protected, into moist
ground, so as to make a path for the electric force, along which,
not finding impediments, it will travel freely, without causing the
least damage. But, like many other simple theories, their practical
execution is not without perplexities. The first of these, in regard
to conductors, arises from the existence of more or less considerable
quantities of metals, to be found in almost every building which
requires protection against lightning. As the use of metals, especially
iron, in the construction of dwellings, both exterior and interior,
is rapidly extending, this becomes a very important consideration
in planning the design of lightning conductors. Of equal moment is
a second point--that of the existence of water or great moisture
under the buildings, or part of them. This must decide invariably
the direction of the conductor towards the earth, and its depth
underground. There are many minor matters to be taken into account, but
these two may be laid down as the chief questions to be kept in view
in settling the best mode of application of any conductors under given
circumstances. It happens often enough that a proper solution as to
what is best is not a little difficult. Still, it can always be arrived
at by careful study, which must, however, be aided by experience.

Keeping always in view the fact that there is nothing whatever that
may be called ‘erratic’ in the manifestations of the electric force,
but that it acts under a ruling principle as strict as that governing
the law of gravity, the first point in designing the protection of any
building will be to clearly ascertain what path the lightning will take
on its course from the clouds to the earth. It is absolutely certain
that the electric force will make its way through materials, termed
good conductors, which allow it free passage, and avoid those of the
opposite class, or bad conductors, the character of every substance on
earth being well known as regards these qualifications, although it
would not be easy to draw sharp lines of demarcation, all conductivity
being relative and not absolute. Looked at in this way, the fundamental
one in the application of lightning conductors, the simplest object for
protection will be a pyramid of stone, such as the Egyptian obelisk,
popularly called ‘Cleopatra’s Needle,’ erected on the Thames Embankment
in the summer of 1878. Stone being a bad conducting material, all that
is necessary to protect it against lightning, provided there is no
metal whatever near it, is to run a thin strip or rope of copper from
the summit to the base, and down into moist earth. Although fragile,
the strip of copper, if uninterrupted and rooted in moisture, will in
this case form an absolute protection. The question assumes another
aspect if, instead of a stone pyramid, a tall factory chimney, not
very dissimilar in outward form, is given as an object for protection.
Here there enters another element. A tall pile of bricks is as bad a
conductor of electricity as a solid mass of stone, but the mass of
bricks constituting a factory chimney is hollow, and the cavity being
filled with smoke and mineral fumes, which are more or less good
conductors of the electric force, the artificial path laid for the free
passage of lightning has to surpass in acceptability the natural one.
In other words, the copper rod laid alongside the factory chimney, to
secure it against damage from lightning, must be considerably thicker
than the one which will protect the simple stone pyramid. It is this
principle which has to be followed all through in the application
of conductors. They must form, in one word, the best path which can
possibly be made for the electric force.

The system employed by Mr. R. S. Newall, F.R.S., for the construction
and erection of lightning conductors is probably the most complete--and
certainly the most representative--of the various methods in vogue in
England. The special study Mr. Newall has made of the subject in all
its bearings, both theoretical and practical, added to the fact of his
possessing at his extensive cable works at Gateshead such exceptional
facilities for the production of copper ropes and bands composed of the
purest metal, render him one of the first authorities on all matters
connected with the application of lightning conductors to buildings. In
describing, therefore, the English method, reference will chiefly be
made to this gentleman’s apparatus and inventions.

The function of a lightning conductor is twofold. In the first
instance, it operates as a medium by which explosions of lightning,
or, to speak more accurately, disruptive discharges of electricity,
are led to the earth freely, and without the risk of their acting
with mechanical force, as they invariably do when compelled to pass
on their way to the earth through so-called non-conductors, that is
to say, bodies possessed of low conductivity, such as the atmosphere,
wood, stone, &c. In the second instance, the conductor acts as a means
whereby the accumulation of electricity existing in the atmosphere
is quietly drawn off and carried noiselessly into the earth, and
dissipated in the subterraneous sheet of water beneath it. Now this
accumulation of electricity, always greatly intensified during a
thunderstorm, invariably seeks the easiest road to earth; this road is
technically called ‘the line of least resistance.’ This line of least
resistance is influenced by various circumstances; the resistance of
any line may be lessened by the presence of streams of warm vapour or
rarefied air such as would come from chimneys, from barns or stacks
containing new hay; by a column of smoke, or by the presence of tall
trees moist from rain. It is not always easy to find the reason why
the lightning takes any particular path, but one thing is certain,
that is, it acts under certain fixed principles, and does not take any
particular route by chance, but always because it is the line of least
resistance. What the lightning conductor really does is to prevent the
possibility of an electric discharge within a certain district, for
instance, in the interior of a house or other building.

From the above remarks, it will easily be seen that lightning
conductors should be made of materials possessing the highest possible
power of conductivity, and be large enough to carry off the heaviest
electric discharge that is ever likely to fall upon them. The various
metals being by far the best conductors of electricity, it follows that
the lightning conductor must be constructed of metal of some kind.
But even metals differ to a great extent in their conducting powers,
as has been shown in a previous chapter. There are, however, only two
metals which are practically available for use as lightning conductors,
namely, iron and copper, and after repeated experiments Mr. E. S.
Newall has arrived at the conclusion that a conductor made of copper
of adequate size is the best--and, in the end, the cheapest--means
of protecting buildings from the effects of lightning. The relative
conductivity of iron and pure copper being as six to one, it follows
that if a copper cable or bar of a given size be sufficient, an
iron cable or bar ought to weigh six times as much per lineal foot
in order to be equally safe. It may be added, that while copper is
more expensive, weight for weight, than iron, it is not so liable to
oxidise; nor, on account of its higher conducting power, is it so
easily fused. The comparative smallness of its mass renders it far more
manageable than iron, and does not interfere with the architectural
features of the building on which it is used. On the contrary, it is
readily adapted to curves and angles.

It may therefore be taken for granted that, almost without exception,
pure copper is the best material that can be used in the construction
of lightning conductors.

[Illustration: Fig. 19.]

[Illustration: Fig. 20.]

[Illustration: Fig. 21.]

The size of the terminal rod or point used in Mr. Newall’s method
varies in length and diameter according to the extent and height of
the building to be protected. As a rule, they are from three to five
feet in length, and from five-eighths to three-quarters of an inch in
diameter; at the upper end they branch out as shown in fig. 19.

In conjunction with this terminal rod a short description of the
‘Auffangstange,’ or ‘reception rod’ of the Germans, may be given.
This ‘reception rod’ (see fig. 21) is made of iron, and varies in
length from ten to thirty feet. It consists of two parts, the higher
part, which measures two-thirds of the whole length, is fastened by a
flange to the lower part of the rod. In fixing this German ‘reception
rod,’ its height and weight have to be taken into consideration. It is
generally made fast by two strong staples, _b_ and _c_, as shown in
fig. 20, which pass through the king post of the roof and are fastened
behind by screw-nuts. The part marked _d_ rests in the lower ring _c_
so that it cannot sink, and the extreme end passes through this ring
_c_ and is screwed tightly to the nut _e_; _f_ is a cap to prevent the
rain getting into the roof.

It is much to be regretted that not only professors and amateurs
studying the manifestations of the electric force, but even learned
societies, such as the French ‘Académie des Sciences,’ should have
spread so many imaginative theories about this ‘reception rod.’ At the
bottom of all was the fancy, not often declared, but still visible in
its expression, of the metallic conductor possessing some occult power
of _attracting_ lightning. In France, as well as in Germany and Italy,
there existed for a long time, and to some extent still exists, quite
a mania for erecting huge rods, such as that shown in the engraving
(see fig. 21), on the top of buildings, the general belief being that
the more high-towering the greater would be the ‘area of protection.’ A
little common sense, brought to the aid of fanciful imaginings, should
have taught the supporters of this ‘area-of-protection’ theory that
it was absolutely untenable. The electric force, seeking its nearest
path to the earth, could not be expected to diverge from it through the
action of a rod raised somewhat higher than the surrounding building;
and the proper method clearly was to bring the metal everywhere as
near to any possible emanation of the force, whether lateral or
vertical, as could be done. Besides being really of no use, except
in rare instances, such as the neighbourhood of high trees, these
tall rods formerly employed, and still frequently seen on the roofs of
buildings, had the detriment of being unsightly, while at times they
were positively dangerous. Instances occurred in which a high wind
threw them down from their elevated position into the road below, on
the heads of passers-by. Thus two persons were killed in Paris in the
summer of 1830 by the fall of a gigantic ‘tige’ from the steeple of
the church of St. Gervais. Either at the same moment, or immediately
before, a stroke of lightning fell upon the church in its lower part,
away from the conductor, making a hole in one of the walls, and then
escaping, without doing further damage, by some iron water-pipes
running underground. The conductor in this case had been constructed
on the model approved by the ‘Académie des Sciences,’ but the accident
conclusively showed that there was no trust to be placed in any mere
theoretical calculations as to the extent of the ‘area of protection.’

A noteworthy example of the fallacy of the ‘area-of-protection’ theory
is to be found in the case of the explosion at the powder magazine
at the Victoria Colliery, BurntclifFe, Yorkshire, which was struck
by lightning and destroyed on August 6, 1878. The instance is also
instructive as showing how important it is that copper conductors
should possess the highest possible conductivity--i.e. be made of the
best and purest copper.

The magazine was an oblong building of brick, nine feet long, five feet
wide, and six feet high (internal dimensions), and it had a uniform
thickness of three bricks. At one end was a heavy iron door, and at
the other a lightning conductor, consisting of a copper-wire rope
seven-sixteenths of an inch in diameter. The point of the terminal rod
was about thirteen feet above the top of the building, and a similar
length was carried into the ground and terminated in clayey soil. The
conductor was fixed to a pole distant about two inches from the end of
the building opposite to that in which the iron door was fixed. _It
was not connected with the iron door in any way._ At the time of the
explosion the magazine contained about 2,000 pounds of gunpowder.

Major Majendie, H.M.’s Chief Inspector of Explosives, in his official
report ascribed the accident to the fact of the iron door being
unconnected with the lightning conductor, and in doing this he was
doubtless right, but only to a limited extent. The author of this work
visited the colliery shortly after the explosion, and found that the
conductor--the weight of which was about one pound per yard--had been
fastened to the pole, which was about twenty-one feet high, by two
glass insulators, and that the conductor was not connected with the
building. On testing the copper rope which formed the conductor, its
conductivity was found to be only 39·2 instead of 93 or 94 per cent.
The conductor, therefore, was but little better than if it had been
made of iron, and, even supposing it had been made of good copper, it
was of too small a size. It should have been of double the weight, and
_not_ insulated from the pole. In order to be thoroughly efficient it
ought to have been brought down the pole, carried through under the
roof, down the iron doorpost, and so into the ground.

According to the French theory, that the ‘area of protection’ afforded
by a lightning conductor is the space contained within the circular
area of a radius double the height of the conductor, the magazine was
thoroughly secured, for the conductor was twenty-one feet high, and the
building only nine feet long, five feet broad, and six feet high. This
case, however, with many others, entirely controverts this theory, and
shows very forcibly the fallacy of an argument that at one time was
accepted almost as an axiom.

One other case of more recent date may be instanced. At Cromer, in
Norfolk, the church--a fine perpendicular building of flint and
freestone, having a tower 159 feet high--was damaged by lightning in
August 1879. During a thunderstorm the lightning struck one of the
pinnacles with considerable force, although on another pinnacle, only
twenty-seven feet six inches distant, a good copper conductor, having
a diameter of five-eighths of an inch, was fixed. On testing the
conductor by means of a galvanometer, it and the earth connection were
found to be in thoroughly good order. After what has been said, comment
on this last example is needless.

[Illustration: Fig. 22.]

The general disposition and adjustment of a lightning conductor demands
the greatest care and consideration. No hard and fast rules can be
laid down, for each individual case must be studied and elaborated by
itself, especially in the instance of large structures, where much
depends upon style, outline, and other details. The main point is that
_every_ part of the building shall be placed beyond the possibility of
being damaged by a disruptive discharge of electricity.

It has been stated previously that the lightning invariably follows
the line of least resistance, and that this line may be influenced by
the presence of streams of warm vapour, columns of smoke, &c., which,
escaping into the air, furnish a ready path for the electric discharge.
Consequently it sometimes happens that a building or barn may be struck
although it be provided with a lightning conductor. In order to
explain this it must be borne in mind that the line of least resistance
is not always the shortest line mathematically. The accompanying
illustration (fig. 22) is an example to the point. It represents a barn
furnished with a lightning conductor and filled with new-made hay,
which is a better conductor of electricity than the material of which
the barn is constructed. This hay is giving off the stream of warm
vapour which is pouring out of the opening at the end, and forms an
invisible band of conducting matter between the thunder-cloud and the
barn, as marked out in the engraving by the dotted lines, the direction
of the wind being shown by the arrow and the trees. Under these
circumstances the discharge of lightning would naturally follow the
path between _c_ and _d_ in preference to the shorter route between _a_
and _b_, because the former is the line of least resistance between the
cloud and the earth. Thus the barn--although furnished with a conductor
in good condition--would most likely be set on fire, or otherwise
damaged. The same deflection of the lightning-stroke might be caused by
a column of smoke, or by the fact of one portion of the building being
moistened by the rain and the other kept dry; an occurrence that might
easily happen when a strong wind is blowing during a storm.

In order to ensure complete protection, the conductor on the barn
should have been carried along the ridge and down the edges of the roof
at each gable. By this means the stroke of lightning would have been
intercepted.

The engraving on the next page shows a design for the protection of a
large detached mansion by means of a multiplication of short points
or terminal rods fixed on all the prominent features of the building.
The conductor is carried along the ridges in every direction, and down
the edges of the roof at each gable. Generally it is sufficient to
have two descending conductors, but occasionally the conformation of
the building or the nature of the ground renders necessary the use of
even more. It is imperative, for obvious reasons, that the descending
portion of the lightning conductor shall be carried from the roof
to the ground by the shortest possible route, and placed in perfect
electrical contact with the earth in the manner to be indicated in a
succeeding chapter.

[Illustration: Fig. 23.]

The projecting points of the conductor are drawn in fig. 23 larger
than they need be, in order to show them more clearly, distinguishing
them from the rest of the building. The same has been done with the
copper rod, running from the roof to the ground and thence into the
earth. In reality a conductor may be made perfectly safe, and yet
all but invisible to the naked eye. For private houses and buildings,
a rope made of copper ought to be at least five-eighths of an inch
in diameter, for a copper rod of half an inch in diameter has never
been known to be fused. For chimneys of manufactories, where gases are
liable to corrode the rope, it had better be a little thicker. Such
copper ropes as those manufactured by Messrs. R. S. Newall and Co.,
five-eighths of an inch in diameter, weighing two-thirds of a pound
per foot, and having a conductivity of 93 per cent., have never been
known to fail in protecting even the largest buildings. It is supposed
by some writers that the value of the conductor is in proportion to
the amount of surface of metal exposed. This, however, is a mistake,
for the conductivity depends on the weight per foot of metal used, the
purity in both being equal. Wire-rope is used simply because it is
so pliable that it is easily handled, and can be made of any length
required without joints.

[Illustration: Fig. 24.]

In fig. 24 is given an illustration of a small detached house, in which
the arrangement of the lightning conductor is indicated by the dark
lines. The method followed is exactly the same in principle as that
employed for the mansion just described. A terminal rod is placed upon
each chimney. These terminal rods are connected with each other by a
copper-rope conductor which is carried along the ridges and gables
of the roof, thus constituting a similar arrangement to the French
‘ridge-circuit’ (_circuit des faîtes_), with the additional advantage
of being far lighter and more sightly. The copper conductor descends
to the earth down the angle formed by the projecting entrance to the
house. By this means every corner of the building is protected; an
important matter in all detached buildings, and especially when they
happen to stand among trees. The preference of the electric force for
trees as its path to the earth in the absence of metal or other bodies
of higher conductivity than trees, has probably no other ground than
their being full of moisture; still this is a disputed question.

Fig. 25 exhibits a slightly different method of arranging the lightning
conductor. In this case the ridges of the roof are surmounted by
ornamental iron-work, instead of the usual terra-cotta, or earthenware,
tiles. This iron-work is utilised and carefully connected with the
conductor. The chimneys, in place of being fitted with terminal rods,
are provided with cast-iron caps--as shown in the engraving--to which
the conductor is attached. The conductor, after descending to the
ridge, is led along it and down the edges of every gable, and is
finally carried down to the ground and connected with the earth in the
usual manner. It is of course absolutely necessary that all masses of
metal, such as gutters, waterspouts, rain-pipes, &c., should be brought
into connection with each other and with the conductor, in order that
the house may constitute one electrically homogeneous body.

It was for a long time held that the protection of churches against
lightning offered special difficulties. This arose mainly from the
constant reports of churches being struck, often when they were
believed to be protected, whereas the accidents arose from the
conductor not being properly fitted. It is even now too often
forgotten that all so-called ‘conductors’ of the electric force are
only so in relation to ‘non-conductors,’ and that, strictly speaking,
all things on earth are to some extent conductors and to some extent
non-conductors. This being kept clearly in view, there is no more
difficulty in protecting the largest cathedral against lightning in the
most efficient manner than in similarly guarding the smallest cottage.

[Illustration: Fig. 25.]

A case in point occurred in May 1879. The steeple of the church at
Laughton-en-le-Morthen was struck by lightning and damaged, the
lightning conductor being thrown down and broken into two pieces. A
correspondence on the subject ensued in the _Times_, and Mr. R. S.
Newall had the remains of the conductor examined, with the following
result:

‘The spire is 175 feet in height, and it had attached to it a thin
tube, made of corrugated copper, about seven-eighths of an inch in
external diameter and five-eighths internal. The copper is about
one-thirty-second of an inch in thickness, and it weighs about one and
a quarter pound per yard. It is made in short lengths, joined together
by screws and coupling pieces, but there is no metallic contact
whatever between the pieces, which are much corroded.

‘The conductor appeared to be fastened to the vane. It was not in
contact with the building, which it ought to have been, but it was kept
at a distance of about two-and-a-half inches from it by twenty-one
insulators. The earth contact was obtained by bending the tube and
burying it in the ground at a depth of from six inches to eighteen
inches, the soil being dry loose rubbish; the length of the earth end
was only three feet, with two short pieces of about a foot in length
each tied to the tube by thin wires, thus forming altogether a most
inefficient conductor. It was placed in a corner formed by a double
stone buttress, which came between the conductor and a lead-covered
roof attached to the spire, the distance between the conductor and the
lead roof being about six feet six inches.

‘The lightning appears to have come down the conductor a certain
distance, and, finding the road to earth bad, it passed through the
buttress, dislodging about two cart-loads of stone, and then came down
the cast-iron down pipes leading from the lead-covered roof and so to
earth.’

Mr. Newall, in writing to the _Times_, goes on to say:—

‘Now if the conductor had been made of copper-wire rope, weighing about
two pounds per yard, and fixed in contact with the spire, without
insulators and with a proper earth contact, no damage whatever would
have been sustained by the building; and if the conductor had been
tested periodically by an expert he would have shown whether the
conductor was good or useless. This examination ought to be insisted
on, as the earth connection is often wilfully destroyed; but I have
never in all my experience known a building which had a conductor
properly fixed to suffer damage from lightning.’

What is really required is to make a lightning conductor of sufficient
calibre to carry down the electric discharge, however great it may be,
from the summit of the building into the earth, and that the earth
contact should be above suspicion and thoroughly good in all seasons.

[Illustration: Fig. 26.]

[Illustration: Fig. 27.]

[Illustration: Fig. 28.]

Fig. 26 shows a plain and simple design for protecting an ordinary
church. The conductor in the case of churches and all other high or
extensive buildings ought invariably to be made of copper rope, other
metals of less conductivity, such as iron, being inadmissible, since
their employment would necessitate the use of ponderous masses of
metal, which would be not only unsightly, but extremely heavy, and
difficult to manipulate successfully. In the accompanying engraving
(fig. 27) lent by the Society for Promoting Christian Knowledge, is
shown a somewhat more complex structure and the method of arranging
the conductors thereon. In this case there is a conductor attached to
each spire, leading to and connected with the metal-work of the roof
and gutters. On the gable _c_, and the transept gables _d e_, there
are fixed three conductors which unite in the centre of the roof, from
which they are carried down to the gutters. The same arrangement is
followed for the smaller gables _f g h_. The water-pipes and gutters
being connected with the conductors, these latter are carried down the
side to the earth. It need scarcely be explained how important it is
that all metal ornaments on the ridges of churches, as well as other
buildings, should either be connected with the general conductors or,
in the case of extensive buildings, with a conductor that is carried
straight to the earth, as shown in fig. 28. In the case of the finials
so often found on Gothic structures, it is necessary to splice the
conductor round the bottom of the finial, as shown in fig. 29. If,
instead of placing terra-cotta tiles along the ridges, a cresting of
fancy iron-work is fixed there, the expense of running a conductor
along the ridges will be saved.

[Illustration: Fig. 29.]

[Illustration: Fig. 30.]

The various methods of fixing weathercocks on to the terminal rod are
fully explained in another chapter. Fig. 30 shows the best arrangement
for connecting the conductor to the terminal rod on a church spire. The
copper rope which forms the conductor is spliced round the terminal
rod at the bottom of the finial, and as an additional security round
the base of the vane rod, which in this instance also serves as the
terminal rod of the lightning conductor.

There has been much controversy as to whether it is better to carry
the conductor from the roof to the ground inside a building than
outside the walls. As a matter of fact, it is a question of very small
importance which way the conductor is carried, so long as it arrives
at the ground by the shortest possible route. Benjamin Franklin, to
judge from many expressions in his works, seems to have been decidedly
in favour of the inside plan, which was adopted almost universally in
France and on the Continent in general on the first introduction of
lightning conductors. But the method was soon abandoned, owing partly
to a witty saying of Voltaire, constantly quoted to this day. Speaking
of the death of the unfortunate Professor Richman, of St. Petersburg,
killed while experimenting with electric discharges from the clouds,
Voltaire remarked, ‘There are some great lords whom one should only
approach with extreme precaution: lightning is such a one.’ A mere
jocular exclamation, it would have had no great force except in France,
where a _bon mot_ may cause the fall of a king and the dethronement of
a dynasty. In regard to Voltaire’s pleasantry about not approaching
too close to lightning, it really had in great part the effect of
preventing conductors to be laid inside the houses. Even such calm
philosophers and men of science as Professor Arago quote Voltaire with
approval. ‘I feel inclined,’ he remarks in his ‘Meteorological Essays,’
‘to admit that the illustrious author (Voltaire) may be right, when I
remember a case that occurred in the United States.’ The case relied
upon, a very curious one, was as follows, in Arago’s own words.

‘Lightning,’ Professor Arago tells his story, ‘having struck a rather
thick rod erected on a Mr. Raven’s house, in Carolina, United States,
afterwards ran along a wire carried down the outside of the house to
connect the rod on the roof with an iron bar stuck in the ground. The
lightning in its descent melted all the part of the wire extending
from the roof to the ground-storey, without injuring in the least the
wall down which the wire was carried. But at a point intermediate
between the ceiling and the floor of the lower storey things were
changed: from thence to the ground the wire was not melted, and at
the spot where the fusion ceased the lightning altered its course
altogether, and, striking off at right angles, made a rather large
hole in the wall and entered the kitchen. The cause of this singular
divergence was readily perceived, when it was remarked that the hole
in the wall was precisely on a level with the upper part of the barrel
of a gun which had been left standing on the floor leaning against the
wall. The gun barrel was uninjured, but the trigger was broken, and a
little further on some damage was done in the fire-place.’ Commenting
upon this case, Professor Arago goes on: ‘Here the lightning went off
horizontally through the wall, in order to strike a fowling-piece
standing upright in the kitchen. How much injury might not have
resulted from this lateral movement, if the lightning had not had to
traverse a thick wall?’ Consequently, he argues, Voltaire is right in
his jocular-oracular declaration about the perils of indoor lightning
conductors, in their being ‘great lords’ dangerous to approach.

It is really difficult to understand how a man like Professor Arago
could be misled into such false reasoning as this about an accident
which, in itself, was of the simplest, and of the very easiest
explanation. That the stroke of lightning falling upon Mr. Raven’s
house, in Carolina, should have melted the wire of the conductor
points to one cause, and to one only, namely, that there was no proper
earth connection. Had it existed, the wire, although thin, could not
possibly have been ‘melted all the part extending from the roof to the
ground-storey,’ nor could the electric force have left its appointed
path to seek a better one through a wall, and, still more astounding,
‘striking off at right angles.’ It is abundantly clear that such
cases, and others to the same effect, brought against the fixing of
lightning-conductors inside the walls of buildings, prove absolutely
nothing. What is beyond controversy is, that a good conductor, in
proper condition, is absolutely harmless to surrounding objects,
including human beings. A man, even with a ‘fowling-piece’ in his
hands, might lean full length against half-an-inch copper rod carrying
off a heavy stroke of lightning into ‘good earth’ without so much as
becoming aware of the passing of the electric discharge. If certainly a
‘grand seigneur,’ as Voltaire remarks, the electric force has this in
common with some of the greatest of men, of not wasting its time, but
following a clear aim.

[Illustration: Fig. 31.]

[Illustration: Fig. 32.]

A very common, and, it may be added, a very mischievous opinion is
prevalent, that lightning conductors should be carefully insulated
from the buildings to which they are attached, and consequently many
conductors are made to pass through insulators of glass and other
materials of low conductivity. This practice of separating the building
from the lightning conductor is not only utterly useless but positively
dangerous. It is not unusually thought that by insulating the conductor
the electric discharge will be prevented from entering the building.
Such an idea is _ipso facto_ absurd, for it is preposterous to suppose
that a flash of lightning which can travel through thousands of feet of
air--itself a very bad conductor of electricity--and then shatter to
pieces the most compact bodies, would be stopped in its course by means
of a few inches of glass, or a few feet of air. It may therefore be
confidently asserted that no insulator can possibly be made that would
be capable of preventing the electric discharge leaving the lightning
conductor provided it could find an easier path leading to the earth.
Mr. Phin, in his work on ‘Lightning-Rods’ says very pertinently:--But
not only are insulators worthless--they are positively dangerous if
the principle upon which they are adopted is fully carried out, which,
however, is but rarely done. A little consideration will show this.
Thus, if a house be furnished with a carefully-insulated lightning-rod,
and should also have any large surface of metal, such as a tin roof,
an extensive system of gutters, or such like, connected with it, it
is easy to see that the house must resemble a large Leyden jar, of
which the tin roof, or other mass of metal, constitutes one coating,
and the lightning-rod and the earth constitute the other, while the
insulators and the dry material of the house represent the glass of the
jar. If both the outside and the inside of this jar (the tin roof and
the earth) had been connected together, it would have been impossible
to have brought one coating into a condition opposite to that of the
other. But the rod being carefully insulated from the roof, it is
obvious that the inductive action of the cloud will bring the roof
and the earth into opposite conditions; and if a man were to form the
path of least resistance between them, the discharge would take place
through his body, and he would probably be destroyed. It is obvious,
then, in the first place, that lightning-rods should be connected with
all large masses of metal which may exist in or upon the house, such
as metallic roofs, tin or iron gutters, or pipes, iron railings, &c.
In the second place, the rod should be attached to the house in the
neatest and least obtrusive manner possible.’

[Illustration: Fig. 33.]

It is indeed desirable for various reasons that the copper rope or band
forming the lightning conductor should be affixed to the building in
the neatest and least obtrusive manner possible. The conductor may be
fastened by means of ordinary metal staples made of stout copper wire.
A better method however is indicated in figs. 31 and 32, one showing
the rope conductor formed of forty-nine wires, usually employed by
Messrs. R. S. Newall and Co. for the protection of ordinary houses
and buildings, and the other the copper band used by them for the
same purpose. This fastening is simply a strap of copper bent to the
required shape and pierced with two holes, by means of which it is
fixed to any building by copper nails or screws. This method possesses
several advantages; it is very sightly and neat, it can be easily
applied without injury to any building, and as it allows the conductor
a certain freedom of movement, it readily permits the contraction and
expansion caused by the variations of temperature. The band conductor
shown here is one inch wide by one-eighth of an inch thick, and weighs
·44 pound per foot. The rope conductor, although it appears less, has
more metal in it; it measures five-eighths of an inch in diameter,
and weighs ·67 pound. Fig. 33 shows a different mode of attaching the
lightning conductor. It is generally used for the heavier ropes.

Fig. 34 exhibits an apparatus called a ‘tightening screw.’ It is used
for making the conductor taut when it gets loose from any cause. The
diagram explains itself, so there is no necessity for describing it.

The tall chimney shafts of factories and similar buildings, from which
smoke or rarefied air escapes, are peculiarly liable to be struck by
lightning. This is principally due to the current of smoke or warmed
air forming, with the soot in the chimney, a medium conductor leading
to the iron-work of the furnace or stove beneath, but ending there--a
result that must be carefully avoided; for although a conductor that
leads past any object is a protection (provided always that it has a
good earth connection), a conductor that leads to an object, and ends
in that object, is a distinct danger. It is therefore necessary to
offer to the electric discharge a better conductor, able to intercept
it and convey it safely to earth on the outside of the shaft.

[Illustration: Fig. 34.]

[Illustration: Fig. 35.]

The mode by which this is generally accomplished in England is by
fixing a copper terminal rod (four or five feet long), on to the side
of the top of the chimney shaft. This method is open to one serious
objection: if the wind should happen to blow the stream of smoke or
heated vapour in a direction opposite to the terminal rod, the electric
discharge might go down the chimney shaft and effect considerable
damage. By far the best plan is that shown in fig. 35. It consists
simply of an iron or copper cap, to the centre of which is attached
the terminal rod. This latter, however, is by no means essential, and
may be said to be merely placed on the top for ornament. A structure
of such small circumference really wants no terminal rod, the most
important thing being to provide a copper rope or band conductor of
sufficient size to carry any electric discharge in safety to the
ground. It will conduce greatly to the strength and stability of such
a conductor if it be built up together with the chimney shaft, and
fastened into the brickwork by clamps on the plan shown in fig. 36. A
conductor of this kind should be made of copper rope or band of much
greater calibre and weight than that used for ordinary buildings. That
made of seven solid wires twisted together (see fig. 37) being the best.

[Illustration: Fig. 36.]

A theory propounded some years ago by the late Prof. Clerk Maxwell,
F.R.S., one of the most eminent physicists in Europe, deserves some
notice here, perhaps more from its ingenuity than its practical
accuracy. On investigation, it proves to be a revival of an old
presumption that it is possible to protect a powder magazine or other
building from the effects of lightning by having its roof, walls, and
ground floor surrounded with a covering of sheet metal, or a network of
lightning conductors, and disconnecting the said covering or network
from the earth, or even insulating it by means of a layer of asphalt or
some similar substance. Prof. Clerk Maxwell argues that the presence of
a lightning conductor induces a larger number of electric discharges
in its immediate neighbourhood than would occur provided no conductor
was present, although at the same time these discharges are rendered
less intense and smaller by reason of the existence of the conductor.
Therefore, it is possible that fewer discharges take place in the area
just outside the radius of the conductor. Reasoning from this, Prof.
Clerk Maxwell considers that an ordinary lightning conductor tends
rather to mitigate the accumulation of electricity in the clouds than
to protect the building on which it is placed.

[Illustration: Fig. 37.]

He says: ‘What we really wish to prevent is the possibility of an
electric discharge taking place within a certain region--say, in the
inside of a gunpowder manufactory. If this is clearly laid down as our
object, the method of securing it is equally clear.

‘An electric discharge cannot occur between two bodies unless the
difference of their potentials (i.e. their electrical conditions)
is sufficiently great, compared with the distance between them. If,
therefore, we can keep the potentials of all bodies within a certain
region equal, or nearly equal, no discharge will take place between
them. We may secure this by connecting all these bodies by means of
good conductors, such as copper wire ropes, but it is not necessary
to do so, for it may be shown by experiment that if every part of the
surface surrounding a certain region is at the same potential, every
point within that region must be at the same potential, provided no
charged body is placed within the region.

‘It would therefore be sufficient to surround our powder-mill with a
conducting material, to sheath its roof, walls, and ground-floor with
thick sheet-copper, and then no electrical effect could occur within
it on account of any thunderstorm outside. There would be no need of
any earth connection. We might even place a layer of asphalt between
the copper floor and the ground, so as to insulate the building. If
the mill were then struck with lightning, it would remain charged for
some time, and a person standing on the ground outside and touching the
wall might receive a shock, but no electrical effect would be perceived
inside, even on the most delicate electrometer. The potential of
everything inside with respect to the earth would be suddenly raised or
lowered as the case might be; but electric potential is not a physical
condition, but only a mathematical conception, so that no physical
effect would be perceived.

‘It is therefore not necessary to connect large masses of metal, such
as engines, tanks, &c., to the walls, if they are entirely within the
building. If, however, any conductor, such as a telegraph-wire, or a
metallic supply-pipe for water or gas, comes into the building from
without, the potential of this conductor may be different from that
of the building, unless it is connected with the conducting shell of
the building. Hence the water or gas supply-pipes, if any enter the
building, must be connected to the system of lightning conductors; and
since to connect a telegraph-wire with the conductor would render the
telegraph useless, no telegraph from without should be allowed to enter
a powder-mill, though there may be electric bells and other telegraphic
apparatus within the building. I have supposed the powder-mill to
be entirely sheathed in thick sheet copper. This, however, is by no
means necessary in order to prevent any sensible electrical effect
taking place within it, supposing it struck by lightning. It is quite
sufficient to enclose the building with a network of a good conducting
substance. For instance, if a copper wire, say No. 4, B. W. G. (0·238
inch diameter) were carried round the foundation of the house, up each
of the corners and gables, and along the ridges, this would probably
be a sufficient protection for an ordinary building against any
thunderstorm in this climate. The copper wire may be built into the
wall to prevent theft, but should be connected to any outside metal,
such as lead or zinc on the roof, and to metal rain-water pipes. In the
case of a powder-mill, it might be advisable to make the network closer
by carrying one or two additional wires over the roof and down the
walls to the wire of the foundation. If there are water or gas-pipes
which enter the building from without, these must be connected with
the system of conducting wires; but if there are no such metallic
connections with distant points, it is not necessary to take any pains
to facilitate the escape of the electricity into the earth; still less
is it advisable to erect a tall conductor with a sharp point in order
to relieve the thunder-clouds of their charge.

[Illustration: Fig. 38. ARRANGEMENT OF PROFESSOR CLERK MAXWELL’S
LIGHTNING CONDUCTORS.]

‘It is hardly necessary to add, that it is not advisable, during a
thunderstorm, to stand on the roof of a house so protected, or to stand
on the ground outside, and lean against the wall.’

Prof. Clerk Maxwell, in a letter to Mr. Charles Tomlinson, F.R.S., the
author of ‘The Thunderstorm,’ says: ‘My plan is to convert a building
into a closed conducting vessel by a sufficient number of wires
enclosing it. For an ordinary house, a skeleton of its edge is quite
enough. A _a_ may be a zinc ridge, B _b_ and C _c_ water-gutters of
zinc or iron; but the pieces A B D, A C E, _a b d_, _a c e_, and the
circuit D E _e d_ should be of stout copper wire or rope, built into
the wall as a security against theft, but connected to every other
piece of metal on the outer surface of the house, and to every gas or
water-pipe which enters the house from without, but _not_ to any masses
of metal wholly within the whole, unless this is desirable for other
purposes.’

[Illustration: Fig. 39.]




CHAPTER XIV.

ACCIDENTS AND FATALITIES FROM LIGHTNING.


The accidents that occur annually from the effects of lightning are
far greater in number and extent than is generally supposed. Although
the art of protecting buildings by means of lightning conductors was
discovered some hundred and twenty-seven years ago, and it is now one
hundred and eleven years since, in 1768, Benjamin Franklin’s ‘lightning
rods’ were first set up over the dome of Saint Paul’s Cathedral, yet
the application of this great discovery is by no means general. At
least one-half, and perhaps two-thirds, of all the public buildings,
including the churches and chapels, of Great Britain and Ireland,
are without any protection against lightning. As to private houses,
it may safely be affirmed that not five out of every thousand are
fitted with lightning conductors. It is well known that the amount of
property annually destroyed by lightning in this country is very great,
though it is, very naturally, impossible to form any accurate, or even
approximate estimate of it. With regard, however, to the number of
deaths from the same cause, certain statistics do exist, although many
of them are notoriously imperfect. According to the ‘Fortieth Report of
the Registrar-General,’ issued in July 1878, and former reports, the
number of deaths from lightning in England and Wales was as follows in
each of the nine years from 1869 to 1877:—

  +--------+-------+---------+-------+
  |  Years | Males | Females | Total |
  +--------+-------+---------+-------+
  |   1869 |   5   |    2    |    7  |
  |   1870 |  13   |    6    |   19  |
  |   1871 |  23   |    5    |   28  |
  |   1872 |  35   |   11    |   46  |
  |   1873 |  17   |    4    |   21  |
  |   1874 |  25   |    —    |   25  |
  |   1875 |  14   |    3    |   17  |
  |   1876 |  15   |    4    |   19  |
  |   1877 |   —   |    —    |   12  |
  +--------+-------+---------+-------+
  | Total  | 147   |   35    |  194  |
  +--------+-------+---------+-------+

The official returns of the number of deaths from lightning, as given
by the English Registrar-General, are admittedly incomplete. In
Prussia, where the registration of the causes of death is most rigidly
enforced by law, and, in consequence, is far more accurate than in
England, there were one thousand and four persons reported as killed
by lightning in the nine years from 1869 to 1877. According to the
official report issued by Dr. Ernst Engel, Director of the Statistical
Bureau of Berlin, the number of lives lost each year was as follows:—

  +--------+-------+---------+-------+
  |  Years | Males | Females | Total |
  +--------+-------+---------+-------+
  |   1869 |   47  |   32    |    79 |
  |   1870 |   59  |   43    |   102 |
  |   1871 |   56  |   47    |   103 |
  |   1872 |   50  |   35    |    85 |
  |   1873 |   61  |   50    |   111 |
  |   1874 |   58  |   49    |   107 |
  |   1875 |   92  |   48    |   140 |
  |   1876 |   59  |   47    |   106 |
  |   1877 |  105  |   66    |   171 |
  +--------+-------+---------+-------+
  | Total  |  587  |  417    | 1,004 |
  +--------+-------+---------+-------+

The population of Prussia is somewhat larger than that of England
and Wales--25¾ millions against 24½ millions--but on the other hand,
thunderstorms are less frequent there than with us. Altogether it will
be rather under than over the mark to say that as many persons are
killed by lightning in England as in Prussia, the loss amounting, on
the average, to over one hundred every year.

Of the deaths by lightning in France, Mons. Boudin some years ago
collected statistics which showed that during the thirty years
beginning in 1834 and ending in 1863, two thousand and thirty-eight
people were struck dead by lightning in that country. During the last
ten years of this period, the deaths amounted to eight hundred and
eighty, and of these only two hundred and forty-three were females.
In connection with this it is a noticeable fact that when a lightning
stroke falls upon a crowd, it almost invariably causes more fatalities
among the men than the women.

In the following tables are given statistics of deaths and accidents
from lightning in the various countries referred to.

In the case of the United States, the Chief of the Bureau of Statistics
writes that no record of deaths or fires caused by lightning is
kept--a somewhat curious admission on the part of such a practical
and methodical country. A similar reply has been received from the
authorities in Spain.


  CAS DE MORT, OCCASIONNÉS PAR LA FOUDRE, DANS LES 49 GOUVERNEMENTS
    DE LA RUSSIE EUROPÉENNE, SANS COMPTER LA FINLANDE ET LES
    GOUVERNEMENTS DU CI-DEVANT ROYAUME DE POLOGNE.

  +--------------------------------+--------+--------+
  |            ANNÉES              | HOMMES | FEMMES |
  +--------------------------------+--------+--------+
  |            1870                |    261 |   139  |
  |            1871                |    260 |   167  |
  |            1872                |    404 |   216  |
  |            1873                |    300 |   179  |
  |            1874                |    227 |   117  |
  +--------------------------------+--------+--------+
  | Total (en cinq années)         |  1,452 |   818  |
  | De ce nombre dans les villes   |     75 |    34  |
  | De ce nombre dans les villages |  1,377 |   784  |
  +--------------------------------+--------+--------+


  INCENDIES, OCCASIONNÉS PAR LA FOUDRE, DANS LES 49 GOUVERNEMENTS
    DE LA RUSSIE EUROPÉENNE, SANS COMPTER LA FINLANDE ET LES
    GOUVERNEMENTS DU CI-DEVANT ROYAUME DE POLOGNE.

  +--------+-----------------+-------------------+
  | ANNÉES | DANS LES VILLES | DANS LES VILLAGES |
  +--------+-----------------+-------------------+
  |  1870  |       11        |        571        |
  |  1871  |       23        |        767        |
  |  1872  |       28        |      1,217        |
  |  1873  |       19        |        908        |
  |  1874  |       12        |        636        |
  +--------+-----------------+-------------------+
  | Total  |       93        |      4,099        |
  +--------+-----------------+-------------------+

    Dans le gouvernement de Cherson les villes Odessa et Nicolaev ne
    sont pas comprises, à cause du manque de renseignements.

The returns from Russia, which include the years 1870, 1871, 1872,
1873, and 1874, are here printed as they were received from the
President of the Commission for Statistics at St. Petersburg.

The returns from Sweden, extending as they do over a period of more
than sixty years, are highly interesting. In this case the difference
in the number of men and women killed is not so noticeable as in other
countries:—


DEATHS BY LIGHTNING IN SWEDEN.

  +------+------+------------------------------------------------------+
  |      |      |                       Of which                       |
  | Year | Total|----------+----------+------+--------+--------+-------+
  |      |      | Under 10 |  Over 10 |      |        | In the | In the|
  |      |      | years old| years old| Males| Females| country| towns |
  +------+------+----------+----------+------+--------+--------+-------+
  | 1877 |   8  |     —    |     8    |   4  |    4   |    7   |    1  |
  | 1876 |  14  |     2    |    12    |   6  |    8   |   14   |    —  |
  | 1875 |  16  |     —    |    16    |  10  |    6   |   16   |    —  |
  | 1874 |   9  |     —    |     9    |   6  |    3   |    9   |    —  |
  | 1873 |  14  |     1    |    13    |   7  |    7   |   13   |    1  |
  | 1872 |  26  |     2    |    24    |  10  |   16   |   25   |    1  |
  | 1871 |   6  |     —    |     6    |   2  |    4   |    5   |    1  |
  | 1870 |   9  |     1    |     8    |   5  |    4   |    9   |    —  |
  | 1869 |   7  |     1    |     6    |   3  |    4   |    7   |    —  |
  | 1868 |  14  |     —    |    14    |  11  |    3   |   14   |    —  |
  | 1867 |   5  |     —    |     5    |   3  |    2   |    5   |    —  |
  | 1866 |  26  |     2    |    24    |   8  |   18   |   25   |    1  |
  | 1865 |  13  |     2    |    11    |   7  |    6   |   13   |    —  |
  | 1864 |   5  |     1    |     4    |   2  |    3   |    4   |    1  |
  | 1863 |   4  |     —    |     4    |   3  |    1   |    4   |    —  |
  | 1862 |  12  |     2    |    10    |  10  |    2   |   11   |    1  |
  | 1861 |  15  |     —    |     —    |   —  |    —   |   15   |    —  |
  | 1860 |   7  |     —    |     —    |   4  |    3   |    7   |    —  |
  | 1859 |  22  |     4    |    18    |  12  |   10   |   20   |    2  |
  | 1858 |  18  |     —    |    18    |  11  |    7   |   17   |    1  |
  | 1857 |   6  |     1    |     5    |   3  |    3   |    6   |    —  |
  | 1856 |   6  |     1    |     5    |   3  |    3   |    6   |    —  |
  | 1855 |  25  |     2    |    23    |  16  |    9   |   25   |    —  |
  | 1854 |   5  |     —    |     5    |   4  |    1   |    5   |    —  |
  | 1853 |   8  |     1    |     7    |   4  |    4   |    8   |    —  |
  | 1852 |  15  |     4    |    11    |   7  |    8   |   14   |    1  |
  | 1851 |   9  |     —    |     9    |   7  |    2   |    9   |    —  |
  | 1850 |   9  |     3    |     6    |   6  |    3   |    9   |    —  |
  | 1849 |  11  |     1    |    10    |   4  |    7   |   10   |    1  |
  | 1848 |   5  |     —    |     5    |   1  |    4   |    5   |    —  |
  | 1847 |  10  |     —    |    10    |   3  |    7   |   10   |    —  |
  | 1846 |  21  |     1    |    20    |  14  |    7   |   21   |    —  |
  | 1845 |  16  |     4    |    12    |  10  |    6   |   14   |    2  |
  | 1844 |  11  |     —    |    11    |   9  |    2   |   10   |    1  |
  | 1843 |   2  |     —    |     2    |   —  |    2   |    2   |    —  |
  | 1842 |   7  |     1    |     6    |   5  |    2   |    7   |    —  |
  | 1841 |   7  |     1    |     6    |   5  |    2   |    7   |    —  |
  | 1840 |   2  |     —    |     2    |   1  |    1   |    2   |    —  |
  | 1839 |  22  |     4    |    18    |  17  |    5   |   22   |    —  |
  | 1838 |  11  |     1    |    10    |   9  |    2   |   11   |    —  |
  | 1837 |   5  |     2    |     3    |   3  |    2   |    5   |    —  |
  | 1836 |   4  |     —    |     4    |   2  |    2   |    4   |    —  |
  | 1835 |   5  |     1    |     4    |   3  |    2   |    5   |    —  |
  | 1834 |  36  |     4    |    32    |  21  |   15   |   36   |    —  |
  | 1833 |   7  |     1    |     6    |   6  |    1   |    7   |    —  |
  | 1832 |   5  |     —    |     5    |   1  |    4   |    5   |    —  |
  | 1831 |   7  |     1    |     6    |   3  |    4   |    7   |    —  |
  | 1830 |   5  |     —    |     —    |   5  |    —   |    —   |    —  |
  | 1829 |  10  |     —    |     —    |   6  |    4   |    —   |    —  |
  | 1828 |   9  |     —    |     —    |   6  |    3   |    —   |    —  |
  | 1827 |   5  |     —    |     —    |   4  |    1   |    —   |    —  |
  | 1826 |  11  |     —    |     —    |   6  |    5   |    —   |    —  |
  | 1825 |   6  |     —    |     —    |   3  |    3   |    —   |    —  |
  | 1824 |   6  |     —    |     —    |   4  |    2   |    —   |    —  |
  | 1823 |   5  |     —    |     —    |   3  |    2   |    —   |    —  |
  | 1822 |   8  |     —    |     —    |   4  |    4   |    —   |    —  |
  | 1821 |   4  |     —    |     —    |   3  |    1   |    —   |    —  |
  | 1820 |  15  |     —    |     —    |   8  |    7   |    —   |    —  |
  | 1819 |  32  |     —    |     —    |  17  |   15   |    —   |    —  |
  | 1818 |  10  |     —    |     —    |   4  |    6   |    —   |    —  |
  | 1817 |   4  |     —    |     —    |   2  |    2   |    —   |    —  |
  | 1816 |   7  |     —    |     —    |   3  |    4   |    —   |    —  |
  +------+------+----------+----------+------+--------+--------+-------+


DEATHS BY LIGHTNING IN BADEN.

  +-------+-------+----------+-------+
  | Year  | Males |  Females | Total |
  +-------+-------+----------+-------+
  | 1874  |   3   |     —    |   3   |
  | 1875  |   3   |     5    |   8   |
  | 1876  |   2   |     7    |   9   |
  +-------+-------+----------+-------+
  | Total |   8   |    12    |   20  |
  +-------+-------+----------+-------+


FIRES THROUGH LIGHTNING IN BAVARIA.

_Right side of Rhine._

  +---------+-------+
  |  Year   | Total |
  +---------+-------+
  | 1843–44 |   24  |
  | 1844–45 |   39  |
  | 1845–46 |   54  |
  | 1846–47 |   25  |
  | 1847–48 |   27  |
  | 1848–49 |   26  |
  | 1849–50 |   30  |
  | 1850–51 |   32  |
  | 1851–52 |   44  |
  | 1852–53 |   60  |
  | 1853–54 |   38  |
  | 1854–55 |   47  |
  | 1855–56 |   70  |
  | 1856–57 |   66  |
  | 1857–58 |   56  |
  | 1858–59 |   60  |
  | 1859–60 |   50  |
  | 1860–61 |   64  |
  | 1861–62 |   63  |
  | 1862–63 |   80  |
  | 1863–64 |   59  |
  | 1864–65 |   90  |
  | 1865–66 |   48  |
  | 1866–67 |  100  |
  | 1867–68 |  140  |
  | 1868–69 |   86  |
  | 1869–70 |   79  |
  | 1870–71 |  115  |
  | 1871–72 |  107  |
  | 1872–73 |  170  |
  +---------+-------+


_Left side of Rhine._

  Year  Total
  1870     6
  1873    36


AUSTRIA. LIST OF DAMAGES BY FIRE THROUGH LIGHTNING.

  Key:
  AWE - Austria, Western Europe
  AEE - Austria, Eastern Europe
  Sa. - Salzburg
  St. - Styria
  K.  - Kärnten
  Il. - Illyria
  Co. - Coastland
  Ty. - Tyrol
  Bo. - Bohemia
  Mä. - Mähren
  Si. - Silesia
  Ga. - Galicia
  Bu. - Buckovina
  D.  - Dalmatia
  +-----+------+-----------------------------------------------------------+
  |     |      |          Of which those through lightning are:—           |
  |Year |Total +---+---+---+---+--+---+---+---+---+---+---+---+---+--+-----+
  |     |Fires |AWE|AEE|Sa.|St.|K.|Il.|Co.|Ty.|Bo.|Mä.|Si.|Ga.|Bu.|D.|Total|
  +-----+------+---+---+---+---+--+---+---+---+---+---+---+---+---+--+-----+
  |1870 | 4,171| 20| 16|  1| 14| 3|  4|  2|  2| 58| 15|  —| 26|  —| —|  161|
  |1871 | 4,293|  9| 26|  1|  9| 5|  2|  3|  1| 53|  8|  1| 34|  4| —|  156|
  |1872 | 5,265| 11| 26|  4| 32| 5| 12|  3|  2| 45| 14|  7| 56|  5| 1|  223|
  |1873 | 5,500| 11| 16|  3| 30| 4| 12|  1| 11| 88| 18|  7| 42|  3| 3|  249|
  |1874 | 5,244| 15| 24|  —| 32| 5|  9|  —|  8| 79| 15|  5| 53|  5| —|  250|
  |1875 | 4,529| 17| 34|  —| 19| 4| 10|  2|  7| 68| 19|  8| 62|  —| —|  250|
  |1876 | 5,001| 18| 13|  1| 22| 5|  5|  1|  1| 59| 15|  —| 48|  —| —|  188|
  |1877 | 6,125| 21| 23|  3| 23| 8|  8|  —|  7| 63| 19|  6| 43|  1| —|  225|
  +-----+------+---+---+---+---+--+---+---+---+---+---+---+---+---+--+-----+
  |Total|40,128|122|178| 13|181|39| 62| 12| 39|513|123| 34|364| 18| 4| 1702|
  +-----+------+---+---+---+---+--+---+---+---+---+---+---+---+---+--+-----+


DEATHS BY LIGHTNING IN WURTEMBERG.

    Year    Total
  1841–42     26
  1851–60    117


DEATHS BY LIGHTNING IN SWITZERLAND.

  +-------+-------+---------+-------+
  |       | Males | Females | Total |
  +-------+-------+---------+-------+
  | 1876  |    2  |    1    |   3   |
  | 1877  |   21  |    9    |  30   |
  +-------+-------+---------+-------+
  | Total |   23  |   10    |  33   |
  +-------+-------+---------+-------+

The data given here is necessarily incomplete, although much trouble
has been taken in obtaining it. Many countries keep no separate records
of deaths and accidents from lightning, and those kept by others
are often meagre and untrustworthy. Still the statistics given are
sufficient to prove that lightning constitutes no unimportant factor
among the dangers that threaten the safety of human life. The apathy
with which the danger is regarded by most people is simply astounding:
very few make any effort to protect themselves or their houses
against it, although during certain months of the year it is almost
impossible to take up a newspaper that does not contain an account
of some fatality or casualty from the effects of a thunderstorm. The
long roll of accidents appended to this chapter shows only too clearly
the enormous amount of damage that has arisen--and is continually
arising--from this source. Public buildings fare little better than
private houses. Even some of the first cathedrals of England have no
lightning conductors whatever, while others, supplied with them, are
insufficiently protected, as is apparent to any competent observer. A
glaring instance of the absence of protection against lightning is to
be found at Windsor Castle. It is a fact that several portions of this
splendid palace, among them St. George’s chapel, and the adjoining
Belfry Tower, are entirely unprovided with lightning conductors. On
other parts of the castle a few conductors are placed, but clearly
not enough. It is needless to say that, speaking only of St. George’s
chapel and the Belfry Tower, these beautiful buildings, constantly
touched by the storm-clouds that sweep up the valley of the Thames, are
liable at any moment to destruction or great damage.

Thomas Fuller, in his ‘Church History of Britain,’ states that--

‘There was scarce a great abbey in England which (once, at the least)
was not burnt down with lightning from Heaven. 1. The Monastery of
Canterbury, burnt anno 1145, and afterwards again burnt anno 1174. 2.
The abbey of Croyland, twice burnt. 3. The Abbey of Peterboro, twice
set on fire. 4. The Abbey of Mary’s in York, burnt. 5. The Abbey of
Norwich, burnt. 6. The Abbey of St. Edmondsbury, burnt and destroyed.
7. The Abbey of Worcester, burnt. 8. The Abbey of Gloucester. 9. The
Abbey of Chichester, burnt. 10. The Abbey of Glastonbury, burnt. 11.
The Abbey of St. Mary in Southwark, burnt. 12. The Church of the Abbey
of Beverley, burnt. 13. The steeple of the Abbey of Evesham, burnt.’

Even in those cases where in modern times lightning conductors have
been applied to buildings, they are very often improperly fixed in
the first instance, or, having once been put up, are never examined
or tested with the view of ascertaining their constant efficiency.
Several accidents owing their origin to one or the other of these
causes have occurred quite recently. In May 1879, the church at
Laughton-en-le-Morthen was struck by lightning and damaged in the
manner described in Chapter XIII. The spire was fitted with a
corrugated copper tube conductor the joints of which were made by
screws and coupling-pieces, but there was no metallic contact between
the lengths; the conductor was insulated from the building; and the
earth-contact was obtained by bending the end of the tubing, and
inserting it about twelve inches deep in dry loose rubbish! Such a
conductor is worse than useless. If it had been examined by a competent
person, it must at once have been utterly condemned. In June 1879,
a disastrous result followed the use of a similar conductor erected
upon a private house near Sheffield. In this case the corrugated tube
forming the conductor contained too little metal, and it was insulated
from the building. The examples show the necessity of leaving the
design and erection of lightning conductors to those persons who have
made a thorough study of the subject, since the work is by no means so
free from complexity as is commonly supposed.

[Illustration: Fig. 40. ST. GEORGE’S CHURCH, LEICESTER.]

Figs. 40 and 41 show the tower and spire of St. George’s Church,
Leicester, after being severely damaged by lightning on August 1st,
1846. The storm, during the course of which it was struck, was very
violent, of prolonged duration, and accompanied by torrents of rain and
hail. Mr. Charles Tomlinson, F.R.S., in his work on ‘The Thunderstorm,’
thus describes the catastrophe:—

‘It was at five minutes past eight, after one or two peals of unusual
distinctness, that the church of St. George was struck with a report
resembling the discharge of cannon, and with a concussion of the air
which shook the neighbouring houses, and extinguished a lamp burning at
the entrance of the News-room, many hundred feet distant. The Sexton
had gone into the church, as usual, to toll the eight o’clock bell;
but was so terrified by the “fire-balls” that he saw in the sky, and
by the fact that once or twice the clapper struck the side of the bell
without his agency, that he made his work as short as possible, and
had just gone out and locked the churchyard gate when the stroke fell.
Two of the spectators of this awful event were Captain Jackson and the
Rev. R. Burnaby, the rector of the parish, who both described the flash
as a vivid stream of light, followed by a red and globular mass of
fire, and darting obliquely from the north-west, with immense velocity,
against the upper part of the spire. For the distance of forty feet
on the eastern side, and nearly seventy on the west, the massive
stone-work of the spire was instantly rent asunder and laid in ruins.
Large blocks of stone were hurled in all directions, broken into small
fragments, and in some cases, as there is every reason to believe,
reduced to powder. One fragment of considerable size was hurled against
the window of a house three hundred feet distant, shattering to pieces
the woodwork, as well as fourteen out of the sixteen panes of glass,
and strewing the room within with fine dust and fragments of glass. It
has been computed that a hundred tons of stone were on this occasion
blown to a distance of thirty feet in three seconds. In addition to
the shivering of the spire, the pinnacles at the angles of the tower
were all more or less damaged, the flying buttresses cracked through
and violently shaken, many of the open battlements at the base of the
spire knocked away, the roof of the church completely riddled, the
roofs of the side-entrances destroyed, and the stone staircases of the
gallery shattered. The top of the spire, when left without support
beneath, fell perpendicularly downwards, inside the steeple, causing
much devastation in its descent. Falling through the uppermost storey,
and carrying along with it the bell and its solid supports, the ruined
spire entered the room containing the clock, dashed the works to
pieces, and penetrating the strong and well-supported floor, descended
with additional momentum through the third and fourth floors (the
latter being that just deserted by the prudent sexton), and reached the
paved vestibule with so furious a shock as to drive in a portion of
the strong foundation-arch, by which the weight of the whole tower was
supported. On looking upward from the scene of ruin in this vestibule,
the tower appeared like a well, so small were the vestiges of its
various storeys.’

[Illustration: Fig. 41. ST. GEORGE’S CHURCH, LEICESTER.]

After minute examination, it was evident that the course of the
lightning had been nearly as follows:—‘The flash first struck the
gilded vane, marks of lightning being perceptible between its bevelled
edges. After traversing the vane and spindle, and the terminating iron
supports, the only path left for the fluid was through a series of
iron cramps, separated by masses of sandstone; and here it was that
the explosion commenced--the stone being torn and hurled aside as it
came in the path of the lightning to the lowest lead lights of the
spire. Most of these iron cramps were found to be powerfully magnetic;
and one of them, eight weeks afterwards, sustained a very considerable
brush of steel filings at its edges. The lattices of the lights on
three sides of the spire were little injured; but on the fourth side
the stone-work was shattered, and the lattice singularly twisted and
partially fused. Here, it appears, another violent explosion took
place, and the lightning diverging struck the north-west pinnacle,
attracted apparently by the copper bolt by which the stones were held
together. It also struck the large cast-iron pipe on the other side
of the spire, reaching from the tower-battlements to the roof of the
church; and during its passage down the pipe, and at an inequality in
the surface of the metal, it displayed the most extraordinary expansive
force, bursting open and scattering to a distance portions of metal of
great solidity and weight. From the leadwork of the roof the lightning
was conducted to the leaden gutters, and so finally to the earth.

‘The course of the remaining current in the interior of the tower
was first to be traced on the lattices of the belfry, then in the
clock-room, where the works of the clock were strongly magnetised,
thence in at least three different directions to the outside of the
tower. The external faces of the clock were not much altered, the hands
were, however, slightly discoloured, and the blackened surfaces of
the dials covered with streaks, as if smeared with a painter’s brush.
On quitting the dial faces on the northern and southern sides of the
tower, the lightning evidently fell upon the leads of the side lobbies,
and was finally carried off by the two iron pipes connecting their
roofs with the earth. Both these pipes were chipped and injured, and
one of them was perforated, as if by a musket-shot, a few inches from
the ground. The edges of this fracture were found to possess magnetic
power. Thus, besides the division of the current at the upper part of
the spire, there was a second division in at least three directions
from the clock-room and dial faces. The roof of the church throughout
its whole extent showed signs of an extraordinary diffusion of the
electric current; and in almost every place where one piece of metal
overlapped another, a powerful explosion had evidently taken place.’

As far as is known the church was unprovided with any lightning
conductor. The same storm produced most disastrous effects in other
parts of the Kingdom. Seven thousand panes of glass were broken by the
hail in the Houses of Parliament; three hundred at the Police Office,
Scotland Yard; other buildings in the metropolis suffered to a similar
extent, the glass in the picture gallery at Buckingham Palace being
totally destroyed and the apartment flooded with water.

[Illustration: Fig. 42. WEST-END CHURCH, SOUTHAMPTON.]

Fig. 42 shows the spire of the church at West End, Southampton, which
was struck by lightning on June 10, 1875. A large quantity of the
stone-work was broken by the passage of the electric discharge, and
some of the pieces were thrown to a great distance.

[Illustration: Fig. 43. MERTON COLLEGE CHAPEL, OXFORD.]

On September 27, 1875, the tower of the chapel of Merton College,
Oxford, was struck by lightning. The damage done was confined to the
mutilation of one of the corner pinnacles and the displacement of
fragments of some of the stone-work which were thrown on to the leads
and the pathway beneath. Some workmen were on the leads at the time,
but fortunately were not hurt. The tower had lately been restored,
and the scaffolding had only been removed a few days previous to the
accident. A gentleman who had taken shelter from the storm in one of
the workmen’s sheds beneath the tower was startled by seeing fragments
of stone falling from above; looking up, he discovered that the tower
had been struck, and immediately informed the college authorities.
On ascending the tower it was found that one of the eight crocketted
pinnacles had been struck. This pinnacle occupied the south-western
corner, and had been completely and cleanly severed from summit to
base. Fortunately, the stone-work displaced--which weighed about three
hundredweight--was thrown on to the roof of the tower, a distance of
twenty-five feet. The vane, slightly fused by the electric discharge,
was found embedded in an upright position in the leads. The mouldings
on the edges of the pinnacle were divided to the extent of four feet,
and many of the stones were turned entirely round.

[Illustration: Fig. 44.]

The tower, which was erected in 1424, and is one of the landmarks of
Oxford, had not up to the time of the accident been provided with
lightning conductors, but they have since been affixed to the building.

Fig. 44 shows the steeple of St. Bride’s Church, Fleet Street, London,
which was severely damaged by lightning on June 18, 1764. The spire of
this steeple is built in four storeys, surmounted by an obelisk. These
four storeys are braced together by means of horizontal iron bars;
another iron bar, about twenty feet long and two inches square, passes
through the upper part of the obelisk and supports the weathercock
and other ornamental work on the top; there is also a great deal of
iron-work used generally in the construction of this part of the
building, thus forming a complete series of discontinuous metallic
masses. When the lightning struck the building it was received by the
long iron bar which supported the vane; at the lower end of the bar
the electric discharge, meeting with no metallic conductor, burst with
great violence, shattering the stone on which the bar rested; the
lightning then pursued its course to earth, leaping from one piece
of metal to another and breaking the stone-work in its way. The last
trace of it was found at the west window of the belfry, from whence it
seems to have found a road to the earth. The damage sustained by the
structure was so great that eighty-five feet of the spire had to be
entirely rebuilt.

The edifice was afterwards attentively examined (as explained in a
previous chapter) by Dr. Watson, a well-known electrician in those
days, who reported to the Royal Society that the accident ‘completely
indicated the great danger of insulated masses of metal to buildings
from lightning; and, on the contrary, evinced the utility and
importance of masses of metal continued and properly conducted, in
defending them from its direful effects. The iron and lead employed
in this steeple, in order to strengthen and preserve it, did almost
occasion its destruction; though, after it was struck by the lightning,
had it not been for these materials keeping the remaining parts
together, a great part of the steeple must have fallen.

[Illustration: Fig. 45.]

Fig. 45 shows the condition of St. Michael’s Church, at Black Rock,
near Cork, after being struck by lightning on January 29, 1836. The
damage done was entirely on the windward side of the steeple, caused,
as is suggested in Mr. Tomlinson’s work, by this side receiving the
greatest quantity of rain, and so being rendered the ‘line of least
resistance,’ but not a sufficiently good conductor to carry off the
discharge to earth.

On Trinity Sunday, June 8th, 1879, a violent thunder-storm broke
over the town of Wrexham about half-past three in the afternoon,
during which the spire of St. Mark’s Church was struck by lightning.
A Sunday-school class was being held in the room at the base of the
spire, and the teacher and five of his scholars were burnt, three of
them severely, and one had his leg broken. Some of the stone-work of
the spire was also displaced and thrown down. The spire was fitted with
a copper conductor, but it was of too small a calibre, and it is very
doubtful whether the earth connection was all it should have been.

Many other cases might be enlarged upon, but enough have been given
to prove the imperative need for a more general use of lightning
conductors on all public and private buildings. Another equally
important necessity is that lightning conductors should be erected on
sound principles, and also be periodically examined and tested by some
competent person.


_PUBLIC BUILDINGS STRUCK BY LIGHTNING._

  +---------+---------------------+------------------+-----------------+
  |  DATE   |       BUILDING      |      DAMAGE      |    AUTHORITY    |
  +---------+---------------------+------------------+-----------------+
  | 1589.   | Nicholas Tower,     | The tower burnt  | From original   |
  |  July 16|  Hamburg            |  down            |  notices in     |
  |         |                     |                  |  Reimarus, Bl.  |
  |         |                     |                  |  315            |
  |         |                     |                  |                 |
  | 1670.   | Nicholas Church,    | Damaged          | Phil. Trans.    |
  |  June 29|  Straland           |                  |  v. 2084        |
  |         |                     |                  |                 |
  | 1673.   | Pharr Church,       | Damaged          | Breslauer       |
  |  June 29|  Epperies, Hungary  |                  |  Samml. 1717,   |
  |         |                     |                  |  p. 64          |
  |         |                     |                  |                 |
  | 1693    | Oundle Church       | Set on fire      | Phil. Trans.    |
  |         |                     |                  |  xvii. 710      |
  |         |                     |                  |                 |
  | 1700.   | Principal church,   | Set on fire and  | Mém. de         |
  |  Oct. 9 |  Troies             |  shattered       |  l’Acad. de Sc. |
  |         |                     |                  |  Paris, 1760,   |
  |         |                     |                  |  p. 65          |
  |         |                     |                  |                 |
  | 1708.   | All Hallows’        | Damaged          | Phil. Trans.    |
  |  July   |  Church, Colchester |                  |  432            |
  |         |                     |                  |                 |
  | 1711.   | Principal town      | Damaged          | Scheuchzer,     |
  |  May 20 |  tower in Bern;     |                  |  Meteorol.      |
  |         |  houses adjoining   |                  |  Helv. p. 35    |
  |         |                     |                  |                 |
  | 1711.   | The belfry of the   | Set on fire      | Scheuchzer,     |
  |  May 23 |  church at Solingen |                  |  Meteorol.      |
  |         |                     |                  |  Helv. p. 28    |
  |         |                     |                  |                 |
  | 1714.   | Elizabeth Tower,    | Damaged          | Breslauer       |
  |  June 21|  Breslau            |                  |  Samml. 1717,   |
  |         |                     |                  |  p. 68          |
  |         |                     |                  |                 |
  | 1717.   | Church at           | Seven persons    | Breslauer       |
  |  July 2 |  Seidenberg, near   |  killed          |  Samml. 1718,   |
  |         |  Zittau             |                  |  p. 1534        |
  |         |                     |                  |                 |
  | 1718.   | Twenty-four         | Set on fire and  | Hist. de        |
  |  April  |  churches between   |  shattered       |  l’Acad. de Sc. |
  |  14, 15 |  Landerneau and     |                  |  Paris, 1719,   |
  |         |  St. P. de Léon,    |                  |  p. 21          |
  |         |  Brittany           |                  |                 |
  |         |                     |                  |                 |
  | 1718.   | Church tower at     | Set on fire      | Breslauer       |
  |  Dec. 14|  Eutin              |                  |  Samml. 1718,   |
  |         |                     |                  |  p. 1968        |
  |         |                     |                  |                 |
  | 1725.   | Church tower,       | Lightning        | Breslauer       |
  |  Dec. 18|  Winterthur         |  followed an     |  Samml. 1725,   |
  |         |                     |  accidental      |  p. 166         |
  |         |                     |  conductor, and  |                 |
  |         |                     |  resulted in     |                 |
  |         |                     |  melting it      |                 |
  |         |                     |                  |                 |
  | 1728.   | Church tower,       | Shattered        | Reimarus, Bl.   |
  |  Aug. 25|  Mellingen, in Baden|                  |  145            |
  |         |                     |                  |                 |
  | 1731.   | Three villages      | Destroyed        | Gent.’s Mag.    |
  |  July   |  near Geneva        |                  |  p. 309         |
  |         |                     |                  |                 |
  | 1732.   | The Escurial at     | Set on fire      | Gent.’s Mag.    |
  |  Oct.   |  Madrid             |                  |  p. 1034        |
  |         |                     |                  |                 |
  | 1743.   | Liberton Church,    | Steeple          | Gent.’s Mag.    |
  |  Aug.   |  Scotland           |  destroyed       |  xiv. 450       |
  |         |                     |                  |                 |
  | 1745.   | Tower of            | Shattered.       | Reimarus, Bl.   |
  |  July 21|  monastery, Bologna |  Lightning       |  93             |
  |         |                     |  followed an     |                 |
  |         |                     |  accidental      |                 |
  |         |                     |  conductor, and  |                 |
  |         |                     |  melted it       |                 |
  |         |                     |                  |                 |
  | 1746.   | Tower of the        | The ball on the  | Reimarus, 198   |
  |  May 21 |  School Church,     |  tower bent,     |                 |
  |         |  Halle              |  and other       |                 |
  |         |                     |  mechanical      |                 |
  |         |                     |  effects         |                 |
  |         |                     |                  |                 |
  | 1747.   | Tower of the        | Physio. and      | Mém. de         |
  |  Aug. 20|  College Church,    |  mechanical      |  l’Acad. de Sc. |
  |         |  Pluviers           |  effects         |  Paris, 1748,   |
  |         |                     |                  |  p. 572         |
  |         |                     |                  |                 |
  | 1748.   | Top of a church     | Shattered and    | Hamburg         |
  |  May 31 |  tower, Witzendorf  |  tore off the    |  Magazine, ix.  |
  |         |                     |  roof; melted    |  301            |
  |         |                     |  and shattered   |                 |
  |         |                     |  accidental      |                 |
  |         |                     |  conductor       |                 |
  |         |                     |                  |                 |
  | 1750.   | Church tower,       | Set on fire      | Phil. Trans.    |
  |  Feb. 5 |  Danbury, Essex     |                  |  xlvi. 611      |
  |         |                     |                  |                 |
  | 1750.   | Tower of Dutch      | Lightning        | Franklin,       |
  |  Spring |  Church, New York   |  followed an     |  Experiments    |
  |         |                     |  accidental      |  and            |
  |         |                     |  conductor,      |  Observations   |
  |         |                     |  which was       |  xv. 180        |
  |         |                     |  shattered, and  |                 |
  |         |                     |  caused other    |                 |
  |         |                     |  mechanical      |                 |
  |         |                     |  effects         |                 |
  |         |                     |                  |                 |
  | 1751.   | Tower of church,    | Lightning        | Phil. Trans.    |
  |  June 6 |  South Moulton,     |  followed an     |  xlvii. 330     |
  |         |  Devonshire         |  accidental      |                 |
  |         |                     |  conductor,      |                 |
  |         |                     |  which was       |                 |
  |         |                     |  shattered, and  |                 |
  |         |                     |  caused other    |                 |
  |         |                     |  mechanical      |                 |
  |         |                     |  effects         |                 |
  |         |                     |                  |                 |
  | 1752.   | Church tower,       | Tower damaged;   | Schwed. Abh.    |
  |  June 19|  Alfwa, Sweden      |  several persons |  xv. 80         |
  |         |                     |  injured         |                 |
  |         |                     |                  |                 |
  | 1753.   | Darlington Church   | Much damaged     | Gent.’s Mag.    |
  |  Mar.   |                     |                  |  xxiii. 145     |
  |         |                     |                  |                 |
  | 1753.   | Church of Les       | Reduced to ashes | Gent.’s Mag.    |
  |  Oct.   |  Filles de St.      |                  |  xxiii. 487     |
  |         |  Sacrament, Naples  |                  |                 |
  |         |                     |                  |                 |
  | 1754.   | Belfry of Newbury   | Point of spire   | Phil. Trans.    |
  |  June 16|  Church             |  shattered,      |  xlix. 307      |
  |         |                     |  accidental      |                 |
  |         |                     |  conductor       |                 |
  |         |                     |  melted, and     |                 |
  |         |                     |  other damage    |                 |
  |         |                     |                  |                 |
  | 1755    | Danish Church,      | Clock damaged    | Phil. Trans.    |
  |         |  Wellclose Square   |                  |  xlix. 298      |
  |         |                     |                  |                 |
  | 1755.   | St. Aubin Church,   | Much damaged     | Gent.’s Mag.    |
  |  Dec.   |  Lorraine           |                  |  xxv. 42        |
  |         |                     |                  |                 |
  | 1757.   | Lostwithiel         | Much damaged     | Gent.’s Mag.    |
  |  Jan.   |  Church, Cornwall   |                  |  xxviii. 427    |
  |         |                     |                  |                 |
  | 1757.   | Christ Church,      | Much damaged     | Gent.’s Mag.    |
  |  Nov.   |  Dublin             |                  |  xxvii. 527     |
  |         |                     |                  |                 |
  | 1759.   | Great Billing       | Steeple          | Ann. Reg. ii.   |
  |  April  |  Church,            |  destroyed       |  84             |
  |         |  Northamptonshire   |                  |                 |
  |         |                     |                  |                 |
  | 1759.   | Portsmouth Church,  | Much damaged     | Gent.’s Mag.    |
  |  May    |  New Hampshire      |                  |  xxix. 355      |
  |         |                     |                  |                 |
  | 1759.   | Jacob Church,       | Several persons  | Reimarus, Bl.   |
  |  June 10|  Aumale             |  injured         |  158            |
  |         |                     |                  |                 |
  | 1760.   | Church, Altona      | Lightning        | Reimarus, 59    |
  |  July 16|                     |  struck the      |                 |
  |         |                     |  copper covering |                 |
  |         |                     |  on the top of   |                 |
  |         |                     |  spire, followed |                 |
  |         |                     |  accidental      |                 |
  |         |                     |  conductors, and |                 |
  |         |                     |  melted them     |                 |
  |         |                     |                  |                 |
  | 1761.   | Shifnal Church,     | Greatly damaged  | Ann. Reg. iv.   |
  |  June   |  Norfolk            |                  |  136            |
  |         |                     |                  |                 |
  | 1761.   | Ludgvan Church,     | Greatly damaged  | Ann. Reg. iv.   |
  |  July   |  near Penzance      |                  |  142            |
  |         |                     |                  |                 |
  | 1763.   | Harrow Church       | Set on fire      | Gent.’s Mag.    |
  |  Mar.   |                     |                  |  xxiii. 142     |
  |         |                     |                  |                 |
  | 1763.   | Salisbury Cathedral | Damaged          | Gent.’s Mag.    |
  |  Mar.   |                     |                  |  xxiii. 143     |
  |         |                     |                  |                 |
  | 1763.   | Southam Church,     | Damaged          | Gent.’s Mag.    |
  |  Mar.   |  Warwickshire       |                  |  xxxiii. 142    |
  |         |                     |                  |                 |
  | 1764.   | St. Bride’s         | Spire struck     | Phil. Trans.    |
  |  June 18|  Church, London     |  and much damaged|  liv. 227       |
  |         |                     |                  |                 |
  | 1765.   | Bicester Church     | Much damaged     | Gent.’s Mag.    |
  |  Aug.   |                     |                  |  xxxv. 391      |
  |         |                     |                  |                 |
  | 1766.   | Skipton-in-Craven   | Much damaged     | Ann. Reg. ix.   |
  |  July   |  Church             |                  |  118            |
  |         |                     |                  |                 |
  | 1766.   | St. Mary’s Church,  | Much damaged     | Ann. Reg. ix.   |
  |  Aug.   |  Bury St. Edmunds   |                  |  122            |
  |         |                     |                  |                 |
  | 1767.   | Provence, France    | Three churches   | Ann. Reg. x. 81 |
  |  April  |                     |  set on fire     |                 |
  |         |                     |                  |                 |
  | 1767.   | Mentz Cathedral     | Set on fire      | Ann. Reg. x. 92 |
  |  May    |                     |                  |                 |
  |         |                     |                  |                 |
  | 1767.   | Nicholas Tower,     | Lightning        | Reimarus, Bl.   |
  |  Aug. 6 |  Hamburg            |  followed        |  291            |
  |         |                     |  accidental      |                 |
  |         |                     |  conductors, and |                 |
  |         |                     |  partly melted   |                 |
  |         |                     |  them            |                 |
  |         |                     |                  |                 |
  | 1767.   | Genoa               | Several          | Ann. Reg. x.    |
  |  Sept.  |                     |  churches damaged|  126            |
  |         |                     |                  |                 |
  | 1768.   | Church tower in     | Damaged.         | Haarlem Verh.   |
  |  Aug. 21|  Alem               |  Several persons |  xiv. 34        |
  |         |                     |  injured         |                 |
  |         |                     |                  |                 |
  | 1770.   | St. Keverns         | Damaged.         | Hemmer, Act.    |
  |  Feb. 18|  Church, Cornwall   |  Several persons |  Acd. Palat.    |
  |         |                     |  injured         |  iv. 37         |
  |         |                     |                  |                 |
  | 1771.   | Nicholas Church,    | Lightning        | Ackermann’s     |
  |  Feb. 2 |  Kiel               |  followed        |  notice, Kiel,  |
  |         |                     |  accidental      |  1772           |
  |         |                     |  conductor, and  |                 |
  |         |                     |  left traces     |                 |
  |         |                     |                  |                 |
  | 1772.   | St. Paul’s          | Lightning        | Arago, iv. 88   |
  |  Mar.   |  Cathedral, London  |  followed        |                 |
  |         |                     |  accidental      |                 |
  |         |                     |  conductor, and  |                 |
  |         |                     |  left traces     |                 |
  |         |                     |                  |                 |
  | 1773.   | Lighthouse at       | Destroyed        | Gent.’s Mag.    |
  |  April  |  Villafranca, Nice  |                  |  xliii. 246     |
  |         |                     |                  |                 |
  | 1773.   | Rhichenback, Saxony | Town reduced to  | Ann. Reg. xvi.  |
  |  June   |                     |  ashes           |  115            |
  |         |                     |                  |                 |
  | 1773    | St. Peter’s         | Shattered the    | Phil. Trans.    |
  |         |  Church, London     |  tower roof      |  lxv. 336       |
  |         |                     |                  |                 |
  | 1774.   | Buckland Church,    | Damaged          | Ann. Reg.       |
  |  Aug.   |  near Dover         |                  |  xvii. 140      |
  |         |                     |                  |                 |
  | 1775.   | St. Colomb Church,  | Much damaged     | Ann. Reg.       |
  |  Feb.   |  Cornwall           |                  |  xviii. 91      |
  |         |                     |                  |                 |
  | 1775.   | A church in Munich  | Tower injured    | Epp. 90         |
  |  June 27|                     |                  |                 |
  |         |                     |                  |                 |
  | 1776.   | Cuckfield Church,   | Much damaged     | Ann. Reg. xix.  |
  |  Aug.   |  Suffolk            |                  |  170            |
  |         |                     |                  |                 |
  | 1778.   | Church in Altona    | Metal melted     | Reimarus, Bl.   |
  |  April  |                     |                  |  64             |
  |  15     |                     |                  |                 |
  |         |                     |                  |                 |
  | 1780.   | Church of the Holy  | Injured          | Reimarus, N.B.  |
  |  Sept.  |  Spirit, Hamburg    |                  |  47             |
  |         |                     |                  |                 |
  | 1780.   | Hammersmith Church  | Much damaged     | Ann. Reg.       |
  |  Oct.   |                     |                  |  xxiii. 230     |
  |         |                     |                  |                 |
  | 1783.   | Ashbourne Church,   | Steeple          | Gent.’s Mag.    |
  |  July   |  Derbyshire         |  demolished      |  liii. 707      |
  |         |                     |                  |                 |
  | 1783    | St. Mary’s,         | Steeple          |                 |
  |         |  Leicester          |  demolished      |                 |
  |         |                     |                  |                 |
  | 1786.   | Church in           | Shattered.       | Act. Acad.      |
  |  June 26|  Wachenheim         |  People injured  |  Theod. Palat.  |
  |         |                     |                  |  vi. 332        |
  |         |                     |                  |                 |
  | 1787.   | St. Mary’s Church,  | Much damaged     | Gent.’s Mag.    |
  |  June   |  Grenoble           |                  |  lvii. 820      |
  |         |                     |                  |                 |
  | 1787.   | Vendamir Church,    | Several persons  | Gent.’s Mag.    |
  |  June   |  Vercovia           |  killed          |  lvii. 820      |
  |         |                     |                  |                 |
  | 1787.   | St. Gregorius       | Set on fire      | Gent.’s Mag.    |
  |  June   |  Church, Prague     |                  |  lvii. 820      |
  |         |                     |                  |                 |
  | 1787.   | Cranbrook Church    | Much damaged     | Gent.’s Mag.    |
  |  June   |                     |                  |  lvii. 824      |
  |         |                     |                  |                 |
  | 1789.   | Pforzheim Church    | Entirely         | Gent.’s Mag.    |
  |  May    |                     |  consumed,       |  lix. 754       |
  |         |                     |  with thirty     |                 |
  |         |                     |  adjoining       |                 |
  |         |                     |  buildings       |                 |
  |         |                     |                  |                 |
  | 1789.   | Barnewell Church,   | Damaged          | Gent.’s Mag.    |
  |  June   |  near Oundle        |                  |  lix. 665       |
  |         |                     |                  |                 |
  | 1790.   | Beckenham Church    | Set on fire      | Ann. Reg.       |
  |  Dec.   |                     |                  |  xxxii. 229     |
  |         |                     |                  |                 |
  | 1790.   | Horsham Church      | Set on fire      | Ann. Reg.       |
  |  Dec.   |                     |                  |  xxxii. 229     |
  |         |                     |                  |                 |
  | 1791.   | Ashton-under-Lyne   | Much damaged     | Ann. Reg.       |
  |  Jan.   |  Church             |                  |  xxxiii. 3      |
  |         |                     |                  |                 |
  | 1791.   | Rainham Church      | Much damaged     | Gent.’s Mag.    |
  |  Oct.   |                     |                  |  lxi. 1050      |
  |         |                     |                  |                 |
  | 1795.   | Castor Church       | Much damaged     | Gent.’s Mag.    |
  |  June   |                     |                  |  lxv. 517       |
  |         |                     |                  |                 |
  | 1795.   | Church in Bergen,   | Set on fire      | Gilb. Ann.      |
  |  Dec. 25|  Norway             |                  |  xxix. 176      |
  |         |                     |                  |                 |
  | 1797.   | Grantham Church     | Damaged          | Gent.’s Mag.    |
  |  July   |                     |                  |  lxviii. 104    |
  |         |                     |                  |                 |
  | 1797.   | Caldecot Church,    | Spire much       | Gent.’s Mag.    |
  |  Aug.   |  Rutland            |  damaged         |  lxvii. 817     |
  |         |                     |                  |                 |
  | 1801.   | Corby Church        | Damaged          | Gent.’s Mag.    |
  |  July   |                     |                  |  lxxi. 659      |
  |         |                     |                  |                 |
  | 1804.   | St. Gertrude        | Burnt by         | Gent.’s Mag.    |
  |  Mar.   |  Church at Nevelles |  lightning       |  lxxiv. 368     |
  |         |                     |                  |                 |
  | 1804.   | St. Maria at        | Burnt by         |                 |
  |  Mar.   |  Oudenard in        |  lightning       |                 |
  |         |  Flanders           |                  |                 |
  |         |                     |                  |                 |
  | 1804.   | Edenham Church,     | Damaged          | Ann. Reg.       |
  |  June   |  Lincoln            |                  |  xlvi. 394      |
  |         |                     |                  |                 |
  | 1804.   | Hanslope Church,    | Spire destroyed  | Ann. Reg.       |
  |  June   |  Bucks              |                  |  xlvi. 395      |
  |         |                     |                  |                 |
  | 1806.   | Sunbury Church,     | Damaged          | Ann. Reg.       |
  |  July   |  Middlesex          |                  |  xlviii. 426    |
  |         |                     |                  |                 |
  | 1807    | Montvilliers        | Damaged          | Howard’s        |
  |         |  Church, France     |                  |  Climate of     |
  |         |                     |                  |  London, ii. 29 |
  |         |                     |                  |                 |
  | 1810.   | Attercliffe Chapel  | Much damaged     | Gent.’s Mag.    |
  |  July   |                     |                  |                 |
  |         |                     |                  |                 |
  | 1811.   | Ashford Church      | Much damaged     | Gent.’s Mag.    |
  |  June   |                     |                  |  lxxxi. 584     |
  |         |                     |                  |                 |
  | 1811.   | Ledbury Parish      | Damaged          | Gent.’s Mag.    |
  |  Dec.   |  Church             |                  |  lxxxi. 650     |
  |         |                     |                  |                 |
  | 1812    | St. Pelverin        | Set on fire and  | Howard’s        |
  |         |  Church, Department |  burnt to the    |  Climate of     |
  |         |  of the Loire       |  ground          |  London, ii. 165|
  |         |                     |                  |                 |
  | 1813    | Bridgwater Church   | Spire destroyed  | Howard’s        |
  |         |                     |                  |  Climate of     |
  |         |                     |                  |  London, ii. 222|
  |         |                     |                  |                 |
  | 1813    | Weston Zoyland      | Tower much       | Howard’s        |
  |         |  Church             |  damaged         |  Climate of     |
  |         |                     |                  |  London, ii. 222|
  |         |                     |                  |                 |
  | 1814.   | Thackstead Church,  | Much damaged     | Gent.’s Mag.    |
  |  Nov.   |  Essex              |                  |  lxxxiv. 491    |
  |         |                     |                  |                 |
  | 1815    | The steeples of     | Struck and set   | Howard’s        |
  |         |  many churches in   |  on fire nearly  |  Climate of     |
  |         |  Belgium, in places |  at the same hour|  London, ii. 259|
  |         |  far distant from   |                  |                 |
  |         |  one another        |                  |                 |
  |         |                     |                  |                 |
  | 1816.   | Worschetz, county   | Church and the   | Ann. Reg.       |
  |  July   |  of Temeswar        |  town greatly    |  lviii. 102     |
  |         |                     |  damaged         |                 |
  |         |                     |                  |                 |
  | 1816.   | Moselle Church      | Damaged          | Ann. Reg.       |
  |  Oct.   |                     |                  |  lviii. 161     |
  |         |                     |                  |                 |
  | 1817.   | St. Paulinas        | Set on fire      | Ann. Reg. lix.  |
  |  Mar.   |  Church, Germany    |                  |  15             |
  |         |                     |                  |                 |
  | 1819.   | St. Martin’s        | Much damaged     | Ann. Reg. lxi.  |
  |  Jan.   |  Church, Guernsey   |                  |  5              |
  |         |                     |                  |                 |
  | 1819.   | Sedgeford Church,   | Much damaged     | Ann. Reg. lxi.  |
  |  July   |  Lynn               |                  |  50             |
  |         |                     |                  |                 |
  | 1821.   | Tower of            | Church burned    | Gilb. Ann.      |
  |  May 7  |  Katherine’s        |                  |  lxviii. 224    |
  |         |  Church,            |                  |                 |
  |         |  Gross-Selten       |                  |                 |
  |         |                     |                  |                 |
  | 1821.   | Wooden Tower of     | Tower burned     | Gilb. Ann.      |
  |  May 7  |  Katherine Church,  |                  |  lxviii. 224    |
  |         |  Tischendorf        |                  |                 |
  |         |                     |                  |                 |
  | 1821.   | Church at Carlsruhe | Damaged          | Gilb. Ann.      |
  |  May 8  |                     |                  |  lxviii. 224    |
  |         |                     |                  |                 |
  | 1821.   | Redcliffe Church,   | Much damaged     | Gent.’s Mag.    |
  |  April  |  Bristol            |                  |  xci. 367       |
  |         |                     |                  |                 |
  | 1822.   | Church at           | Damaged          | Wurtemberger    |
  |  Jan. 15|  Gerstetten         |                  |  Jahreshafte,   |
  |         |                     |                  |  xi. 463        |
  |         |                     |                  |                 |
  | 1822.   | North Luffenham     | Much damaged     | Gent.’s Mag.    |
  |  June   |  Church, Rutland    |                  |  xcii. 636      |
  |         |                     |                  |                 |
  | 1822.   | Church at Chatham   | Spire ripped     | Tomlinson’s     |
  |  Aug.   |                     |  open            |  Thunderstorm,  |
  |         |                     |                  |  p. 165         |
  |         |                     |                  |                 |
  | 1822.   | Rouen Cathedral     | Set on fire      | Tomlinson’s     |
  |  Sept.  |                     |                  |  Thunderstorm,  |
  |         |                     |                  |  p. 165         |
  |         |                     |                  |                 |
  | 1822.   | St. Peter’s         | Reduced to ruins | Gent.’s Mag.    |
  |  Oct.   |  Church, Venice     |                  |  xcii. 553      |
  |         |                     |                  |                 |
  | 1823    | Kemble Church,      | Spire destroyed  | Howard’s        |
  |         |  Wilts              |                  |  Climate of     |
  |         |                     |                  |  London, iii.   |
  |         |                     |                  |  135            |
  |         |                     |                  |                 |
  | 1823.   | Shaugh Church,      | Tower struck     | Tomlinson’s     |
  |  Feb.   |  near Plymouth      |  and much        |  Thunderstorm,  |
  |         |                     |  shattered. An   |  p. 165         |
  |         |                     |  iron conductor  |                 |
  |         |                     |  had been        |                 |
  |         |                     |  erected about   |                 |
  |         |                     |  two years       |                 |
  |         |                     |  before, but     |                 |
  |         |                     |  this had rusted |                 |
  |         |                     |  and gone to     |                 |
  |         |                     |  decay           |                 |
  |         |                     |                  |                 |
  | 1824.   | Church at           | Damaged          | Würtemberger    |
  |  July 10|  Simmerfeld         |                  |  Jahreshafte,   |
  |         |                     |                  |  xi. 463        |
  |         |                     |                  |                 |
  | 1824.   | Charles Church,     | Steeple struck,  | Tomlinson’s     |
  |  Nov.   |  Plymouth           |  and the small   |  Thunderstorm,  |
  |         |                     |  brass rod       |  p. 165         |
  |         |                     |  erected as      |                 |
  |         |                     |  a lightning     |                 |
  |         |                     |  conductor       |                 |
  |         |                     |  knocked to      |                 |
  |         |                     |  pieces          |                 |
  |         |                     |                  |                 |
  | 1825—   | Torrington Church,  | Tower and        | Tomlinson’s     |
  |  about  |  North Devon        |  steeple ruined. |  Thunderstorm,  |
  |         |                     |  They had to be  |  p. 165         |
  |         |                     |  rebuilt         |                 |
  |         |                     |                  |                 |
  | 1826.   | Alphington Church,  | Much damaged     | Ann. Reg.       |
  |  June   |  near Exeter        |                  |  1826, p. 97    |
  |         |                     |                  |                 |
  | 1827    | Pailant Church,     | Considerably     | Howard’s        |
  |         |  Chichester         |  damaged         |  Climate of     |
  |         |                     |                  |  London, iii.   |
  |         |                     |                  |  259            |
  |         |                     |                  |                 |
  | 1827.   | Church Tower,       | Set on fire,     | Würtemberger    |
  |  Jan. 11|  Bussen             |  although        |  Jahreshafte,   |
  |         |                     |  covered with    |  xi. 463        |
  |         |                     |  snow            |                 |
  |         |                     |                  |                 |
  | 1828.   | Edlesborough Church | Set on fire      | Gent.’s Mag.    |
  |  April  |                     |                  |  xcviii. 358    |
  |         |                     |                  |                 |
  | 1828.   | Kingsbridge         | Steeple rent,    | Tomlinson’s     |
  |  June   |  Church, Devon      |  and other damage|  Thunderstorm,  |
  |         |                     |                  |  p. 165         |
  |         |                     |                  |                 |
  | 1828.   | Kilcoleman Church,  | Spire destroyed  | Ann. Reg. p.    |
  |  Oct.   |  co. Mayo           |                  |  131            |
  |         |                     |                  |                 |
  | 1830.   | Independent         | Damaged          | Ann. Reg. p.    |
  |  July   |  Chapel, Edgworth   |                  |  101            |
  |         |  Moor, near Bolton  |                  |                 |
  |         |                     |                  |                 |
  | 1830.   | Marlborough         | Tower and        | Tomlinson’s     |
  |  Aug.   |  Church, near       |  church severely |  Thunderstorm,  |
  |         |  Kingsbridge, Devon |  damaged         |  p. 166         |
  |         |                     |                  |                 |
  | 1831.   | Kilmichael Church,  | Much damaged     | Ann. Reg. p. 39 |
  |  Feb.   |  Glassire           |                  |                 |
  |         |                     |                  |                 |
  | 1833.   | Strasburg Cathedral | Much damaged     | Builder, ii. 39 |
  |  Aug.   |                     |                  |                 |
  |         |                     |                  |                 |
  | 1835.   | Church Tower,       | Much shattered   | Würtemb.        |
  |  May 16 |  Endersbach         |                  |  Jahreshafte,   |
  |         |                     |                  |  xi. 465        |
  |         |                     |                  |                 |
  | 1835.   | Durham Cathedral    | Western tower    | Ann. Reg. p. 94 |
  |  June   |                     |  damaged         |                 |
  |         |                     |                  |                 |
  | 1836.   | Black Rock, near    | Spire demolished | Tomlinson’s     |
  |  Jan.   |  Cork               |                  |  Thunderstorm,  |
  |         |                     |                  |  p. 166         |
  |         |                     |                  |                 |
  | 1836.   | Christ Church,      | The spire        | Tomlinson’s     |
  |  Nov.   |  Doncaster          |  shattered and   |  Thunderstorm,  |
  |         |                     |  the church      |  p. 166         |
  |         |                     |  greatly         |                 |
  |         |                     |  injured. The    |                 |
  |         |                     |  roof was        |                 |
  |         |                     |  smashed in, and |                 |
  |         |                     |  the churchyard  |                 |
  |         |                     |  presented       |                 |
  |         |                     |  a scene of      |                 |
  |         |                     |  ruin and        |                 |
  |         |                     |  devastation.    |                 |
  |         |                     |  The spire was   |                 |
  |         |                     |  surmounted by a |                 |
  |         |                     |  ball of glass   |                 |
  |         |                     |  to keep off the |                 |
  |         |                     |  lightning!      |                 |
  |         |                     |                  |                 |
  | 1837.   | Hoo Church, Kent    | Set on fire      | Gent.’s Mag.    |
  |  June   |                     |                  |  N.S. viii. p.  |
  |         |                     |                  |  80             |
  |         |                     |                  |                 |
  | 1839.   | Church tower in     | Damaged          | Arago, Notiz,   |
  |  Jan 8  |  Hasselt            |                  |  125            |
  |         |                     |                  |                 |
  | 1841.   | Spitalfields,       | Spire rent, and  | Tomlinson’s     |
  |  Jan.   |  London             |  other damages   |  Thunderstorm,  |
  |         |                     |                  |  p. 166         |
  |         |                     |                  |                 |
  | 1841    | Streatham           | Spire nearly     | Tomlinson’s     |
  |         |                     |  destroyed, and  |  Thunderstorm,  |
  |         |                     |  church set on   |  p. 166         |
  |         |                     |  fire            |                 |
  |         |                     |                  |                 |
  | 1841.   | Walton Church,      | Spire destroyed  | Tomlinson’s     |
  |  May 10 |  Stafford           |                  |  Thunderstorm,  |
  |         |                     |                  |  p. 166         |
  |         |                     |                  |                 |
  | 1841.   | St. Michael’s,      | Beautiful spire  | Tomlinson’s     |
  |  Aug. 24|  Liverpool          |  shattered, and  |  Thunderstorm,  |
  |         |                     |  clock injured   |  p. 166         |
  |         |                     |                  |                 |
  | 1841.   | St. Martin’s,       | Spire            | Tomlinson’s     |
  |  Aug. 24|  Liverpool          |  shattered, and  |  Thunderstorm,  |
  |         |                     |  other damage    |  p. 166         |
  |         |                     |                  |                 |
  | 1841    | Wolverhampton       | Set on fire      | Annals of       |
  |         |  Parish Church      |                  |  Electricity,   |
  |         |                     |                  |  vi. 504        |
  |         |                     |                  |                 |
  | 1841    | Spitalfields Church | Steeple damaged  | Annals of       |
  |         |                     |                  |  Electricity,   |
  |         |                     |                  |  vi. 504        |
  |         |                     |                  |                 |
  | 1842.   | Brixton Church,     | Dome and         | Tomlinson’s     |
  |  April  |  London             |  building much   |  Thunderstorm,  |
  |  24     |                     |  rent            |  p. 166         |
  |         |                     |                  |                 |
  | 1842.   | St. Martin’s,       | Spire            | Tomlinson’s     |
  |  July 28|  London             |  shattered; cost |  Thunderstorm,  |
  |         |                     |  of repair,      |  p. 166         |
  |         |                     |  1,500_l._       |                 |
  |         |                     |                  |                 |
  | 1843.   | Exton Church,       | Spire            | Tomlinson’s     |
  |  April  |  Rutland            |  destroyed;      |  Thunderstorm,  |
  |  25     |                     |  church set on   |  p. 166         |
  |         |                     |  fire and nearly |                 |
  |         |                     |  destroyed       |                 |
  |         |                     |                  |                 |
  | 1843.   | St. Mark’s, Hull    | Slightly damaged | Tomlinson’s     |
  |  May 25 |                     |                  |  Thunderstorm,  |
  |         |                     |                  |  p. 166         |
  |         |                     |                  |                 |
  | 1843.   | North Huish, near   | Steeple          | Tomlinson’s     |
  |  Oct.   |  Modbury, Devon     |  shattered       |  Thunderstorm,  |
  |         |                     |                  |  p. 166         |
  |         |                     |                  |                 |
  | 1844.   | Oving Church, near  | Spire damaged    | Tomlinson’s     |
  |  Mar.   |  Chichester         |                  |  Thunderstorm,  |
  |         |                     |                  |  p. 166         |
  |         |                     |                  |                 |
  | 1844    | St. Clement’s,      | Clock injured    | Tomlinson’s     |
  |         |  London             |                  |  Thunderstorm,  |
  |         |                     |                  |  p. 166         |
  |         |                     |                  |                 |
  | 1844.   | Magdalen Tower,     | One of the       | Tomlinson’s     |
  |  July   |  Oxford             |  pinnacles       |  Thunderstorm,  |
  |         |                     |  damaged;        |  p. 166         |
  |         |                     |  staircase       |                 |
  |         |                     |  injured         |                 |
  |         |                     |                  |                 |
  | 1844.   | Stannington         | Seriously        | Tomlinson’s     |
  |  July 20|  Church, near       |  damaged         |  Thunderstorm,  |
  |         |  Sheffield          |                  |  p. 166         |
  |         |                     |                  |                 |
  | 1846.   | Church near         | Damaged          | Compt. Rend.    |
  |  June 14|  Chambrey           |                  |  xxiii. 153     |
  |         |                     |                  |                 |
  | 1846.   | St. George’s        | Spire destroyed  | Builder, iv.    |
  |  Aug.   |  Church, Leicester  |                  |  395            |
  |         |                     |                  |                 |
  | 1846.   | Dedham Church,      | Much damaged     | Builder, iv.    |
  |  Aug.   |  Essex              |                  |  395            |
  |         |                     |                  |                 |
  | 1846.   | Village of          | Completely       | Journal des     |
  |  Oct.   |  Schledorf, near    |  destroyed       |  Debats, Oct.   |
  |         |  Munich             |                  |  20, 1846       |
  |         |                     |                  |                 |
  | 1847.   | Her Majesty’s       | One tower much   | Builder, vii.   |
  |  June   |  palace, Osborne    |  damaged         |  291            |
  |         |                     |                  |                 |
  | 1847.   | Church in Thann     | Much damaged     | Compt. Rend.    |
  |  June   |                     |                  |  xxix. 485      |
  |         |                     |                  |                 |
  | 1847.   | Walton Church,      | Lightning        | Tomlinson’s     |
  |  Aug.   |  Lincolnshire       |  entered at the  |  Thunderstorm,  |
  |         |                     |  belfry; one man |  p. 158         |
  |         |                     |  killed, several |                 |
  |         |                     |  injured         |                 |
  |         |                     |                  |                 |
  | 1849.   | St. Saviour’s,      | Damaged          | Ann. Reg. xci.  |
  |  July   |  Southwark          |                  |  80             |
  |         |                     |                  |                 |
  | 1850.   | Norton-by-Gaulby    | Spire much       | Builder, viii.  |
  |  May    |  Church             |  damaged         |  248            |
  |         |                     |                  |                 |
  | 1850.   | Little Stretton     | Much damaged     | Builder, viii.  |
  |  May    |  Church             |                  |                 |
  |         |                     |                  |                 |
  | 1850.   | Roman Catholic      | Bell-turret      | Builder, viii.  |
  |  Aug.   |  Church, York       |  shattered       |  405            |
  |         |                     |                  |                 |
  | 1850.   | Keysoe Church       | Considerably     | Builder, viii.  |
  |  Oct.   |                     |  damaged         |  509            |
  |         |                     |                  |                 |
  | 1850.   | Cobridge Church,    | Considerably     | Builder, viii.  |
  |  Nov.   |  Potteries          |  damaged         |  533            |
  |         |                     |                  |                 |
  | 1851.   | St. Sepulchre’s     | Much damaged     | Builder, ix.    |
  |  May    |  Church, Northampton|                  |  329            |
  |         |                     |                  |                 |
  | 1851.   | Edinburgh Assembly  | Much damaged     | Builder, ix.    |
  |  May    |  Hall               |                  |  305            |
  |         |                     |                  |                 |
  | 1851.   | Boulogne Cathedral  | Dome damaged     | Builder, ix.    |
  |  June   |                     |                  |  415            |
  |         |                     |                  |                 |
  | 1852.   | Ross Church,        | Severely damaged | Tomlinson’s     |
  |  July 6 |  Hereford           |                  |  Thunderstorm,  |
  |         |                     |                  |  p. 166         |
  |         |                     |                  |                 |
  | 1852.   | Woolpit Church,     | Tower and spire  | Builder, x. 492 |
  |  July   |  Suffolk            |  destroyed       |                 |
  |         |                     |                  |                 |
  | 1852.   | Leighton Buzzard    | Much damaged     | Builder, x. 492 |
  |  July   |  Church             |                  |                 |
  |         |                     |                  |                 |
  | 1852    | Exton Parish Church | Church nearly    | Builder, xii.   |
  |         |                     |  destroyed       |  575            |
  |         |                     |                  |                 |
  | 1853.   | Derby Church        | Much damaged     | Builder, xi. 28 |
  |  Jan.   |                     |                  |                 |
  |         |                     |                  |                 |
  | 1853.   | Parish Church,      | Entirely         | Builder, xi. 43 |
  |  Jan.   |  Eskdalemuir,       |  destroyed       |                 |
  |         |  Dumfries           |                  |                 |
  |         |                     |                  |                 |
  | 1853.   | Lincoln Cathedral   | Struck           | Tomlinson’s     |
  |  Feb.   |                     |  north-west      |  Thunderstorm,  |
  |         |                     |  pinnacle of     |  p. 166         |
  |         |                     |  the broad       |                 |
  |         |                     |  tower; set on   |                 |
  |         |                     |  fire; narrowly  |                 |
  |         |                     |  escaped         |                 |
  |         |                     |  destruction     |                 |
  |         |                     |                  |                 |
  | 1853.   | Skipton Church      | Much damaged     | Builder, xi.    |
  |  July   |                     |                  |  423            |
  |         |                     |                  |                 |
  | 1853.   | Hereford Old        | Slightly damaged | Builder, xi.    |
  |  July   |  Parish Church      |                  |  487            |
  |         |                     |                  |                 |
  | 1853.   | Chaddesley Corbett  | Considerably     | Builder, xi.    |
  |  Nov.   |  Church             |  damaged         |  704            |
  |         |                     |                  |                 |
  | 1854.   | Hanwell Church      | Spire much       | Builder, xii.   |
  |  May    |                     |  damaged         |  283            |
  |         |                     |                  |                 |
  | 1854.   | Helpringham Church  | Spire much       | Builder, xii.   |
  |  May    |                     |  damaged         |  269            |
  |         |                     |                  |                 |
  | 1854.   | Ealing Church       | Had a common     | Tomlinson’s     |
  |  June   |                     |  conductor,      |  Thunderstorm,  |
  |         |                     |  which was       |  p. 167         |
  |         |                     |  fused; the      |                 |
  |         |                     |  church slightly |                 |
  |         |                     |  damaged         |                 |
  |         |                     |                  |                 |
  | 1854.   | Ashbury Church      | Had a common     | Tomlinson’s     |
  |  July   |                     |  conductor,      |  Thunderstorm,  |
  |         |                     |  which was       |  p. 167         |
  |         |                     |  fused; church   |                 |
  |         |                     |  damaged, but    |                 |
  |         |                     |  not considerably|                 |
  |         |                     |                  |                 |
  | 1854.   | Tower of Magdalen   | Much damaged     | Tomlinson’s     |
  |  July 19|  College, Oxford    |                  |  Thunderstorm,  |
  |         |                     |                  |  p. 167         |
  |         |                     |                  |                 |
  | 1854.   | National School     | Three children   | Ann. Reg.       |
  |  Aug.   |  Chapel, St. Mary,  |  killed, several |  xcvi. 140      |
  |         |  Ipswich            |  injured         |                 |
  |         |                     |                  |                 |
  | 1855.   | Trinity Church,     | Slightly damaged | Builder, xiii.  |
  |  May    |  Southwark          |                  |  239            |
  |         |                     |                  |                 |
  | 1855.   | St. Mark’s,         | Considerably     | Builder, xiii.  |
  |  May    |  Myddelton Square   |  damaged         |  239            |
  |         |                     |                  |                 |
  | 1855.   | Holy Trinity        | Slightly damaged | Builder, xiii.  |
  |  July   |  Church, Brompton   |                  |  348            |
  |         |                     |                  |                 |
  | 1855.   | St. Ebbe’s Parish   | Slightly damaged | Builder, xiii.  |
  |  July   |  Church             |                  |  348            |
  |         |                     |                  |                 |
  | 1856.   | Chimney at          | Much damaged;    | Tomlinson’s     |
  |  Feb.   |  Liverpool, 310 ft. |  struck at 20    |  Thunderstorm,  |
  |         |  high               |  yds. below the  |  p. 167         |
  |         |                     |  top             |                 |
  |         |                     |                  |                 |
  | 1856.   | Hemingbrough Ch.    | Much damaged     | Builder, xiv.   |
  |  June   |                     |                  |  348            |
  |         |                     |                  |                 |
  | 1856.   | Clapton Church      | Much damaged     | Builder, xiv.   |
  |  July   |                     |                  |  391            |
  |         |                     |                  |                 |
  | 1856    | Addlethorpe Church, | Much damaged     | Builder, xiv.   |
  |         |                     |                  |  391            |
  |  July   |  Lincolnshire       |                  |                 |
  |         |                     |                  |                 |
  | 1856.   | Church of St.       | Much damaged     | Tomlinson’s     |
  |  July 14|  Ebbe, Oxford       |                  |  Thunderstorm,  |
  |         |                     |                  |  p. 167         |
  |         |                     |                  |                 |
  | 1856.   | Holy Trinity        | Much damaged     | Builder, xiv.   |
  |  Aug.   |  Church, Manchester |                  |  451            |
  |         |                     |                  |                 |
  | 1857.   | Parish Church,      | Steeple set on   | Tomlinson’s     |
  |  May    |  Wisborough, Sussex |  fire            |  Thunderstorm,  |
  |         |                     |                  |  p. 167         |
  |         |                     |                  |                 |
  | 1857    | Walgrave Church     | Damaged          | Tomlinson’s     |
  |         |                     |                  |  Thunderstorm,  |
  |         |                     |                  |  p. 167         |
  |         |                     |                  |                 |
  | 1857.   | Wargrave Church,    | Pinnacle         | Tomlinson’s     |
  |  May    |  Twyford            |  destroyed       |  Thunderstorm,  |
  |         |                     |                  |  p. 167         |
  |         |                     |                  |                 |
  | 1857.   | Tower of Windsor    | Four tons        | Tomlinson’s     |
  |  Aug.   |  Castle             |  of parapet      |  Thunderstorm,  |
  |         |                     |  demolished      |  p. 167         |
  |         |                     |                  |                 |
  | 1857    | Independent         | Set on fire      | Tomlinson’s     |
  |         |  Chapel, Portsmouth |                  |  Thunderstorm,  |
  |         |                     |                  |  p. 167         |
  |         |                     |                  |                 |
  | 1857.   | St. Michael’s       | Pinnacle         | Tomlinson’s     |
  |  Aug.   |  Church, Stamford   |  demolished      |  Thunderstorm,  |
  |         |                     |                  |  p. 167         |
  |         |                     |                  |                 |
  | 1857    | Trinity Church,     | Struck during    | Tomlinson’s     |
  |         |  Southwark          |  service         |  Thunderstorm,  |
  |         |                     |                  |  p. 167         |
  |         |                     |                  |                 |
  | 1857.   | A gasometer at      | Struck, and gas  | Builder, xv.    |
  |  Aug.   |  the Chartered Gas  |  ignited         |  488            |
  |         |  Co.’s works, St.   |                  |                 |
  |         |  Luke’s             |                  |                 |
  |         |                     |                  |                 |
  | 1858.   | The monument to     | Slightly injured |                 |
  |  July   |  Dugald Stuart at   |                  |                 |
  |         |  Edinburgh          |                  |                 |
  |         |                     |                  |                 |
  | 1858.   | Peak Hall, near     | Church struck;   | Tomlinson’s     |
  |  July   |  Stoke-on-Trent     |  roof damaged,   |  Thunderstorm,  |
  |         |                     |  walls seriously |  p. 167         |
  |         |                     |  fractured, and  |                 |
  |         |                     |  organ injured   |                 |
  |         |                     |                  |                 |
  | 1862.   | Mashbury Church,    | Set on fire      | Builder, xx.    |
  |  May    |  Essex              |                  |  391            |
  |         |                     |                  |                 |
  | 1862.   | Bampton Parish      | Much damaged     | Builder, xx.    |
  |  May    |  Church             |                  |  391            |
  |         |                     |                  |                 |
  | 1862.   | Rainham Parish      | Damaged          | Builder, xx.    |
  |  May    |  Church, Kent       |                  |  391            |
  |         |                     |                  |                 |
  | 1862.   | Tackley (near       | Much damaged     | Building News,  |
  |  July   |  Woodstock) Parish  |                  |  1862, p. 77    |
  |         |  Church             |                  |                 |
  |         |                     |                  |                 |
  | 1863.   | Dunoon Church,      | Nearly destroyed | Builder, xxi.   |
  |  Feb.   |  Scotland           |                  |  140            |
  |         |                     |                  |                 |
  | 1863.   | St. Paul’s Church,  | Considerably     | Building News,  |
  |  June   |  Manchester         |  damaged         |  1863, p. 457   |
  |         |                     |                  |                 |
  | 1864.   | St. Mary, York      | Slightly damaged | Builder, xxii.  |
  |  Sept.  |                     |                  |  691            |
  |         |                     |                  |                 |
  | 1865    | St. Lawrence,       | Much damaged     | Builder,        |
  |  Jan.   |  Nuremberg, Bavaria |                  |  xxiii. 53      |
  |         |                     |                  |                 |
  | 1865.   | St. Mary’s Church,  | Much damaged     | Builder,        |
  |  July   |  Stamford           |                  |  xxiii. 526     |
  |         |                     |                  |                 |
  | 1865.   | St. Botolph         | Much damaged     | Builder,        |
  |  July   |  Church, Boston     |                  |  xxiii. 526     |
  |         |                     |                  |                 |
  | 1865.   | Roman Catholic      | Much damaged     | Builder,        |
  |  July   |  Chapel, Colchester |                  |  xxiii. 526     |
  |         |                     |                  |                 |
  | 1867.   | Sutton-in-Ashfield  | Spire destroyed  | Builder, xxv.   |
  |  Sept.  |  Church,            |                  |  695            |
  |         |  Nottinghamshire    |                  |                 |
  |         |                     |                  |                 |
  | 1867.   | St. Pé-Saint-Simon  | Much damaged     | Builder, xxv.   |
  |  Sept.  |  Church, France     |                  |  684            |
  |         |                     |                  |                 |
  | 1867.   | Sanzet Church       | Set on fire      | Builder, xxv.   |
  |  Sept.  |                     |                  |  684            |
  |         |                     |                  |                 |
  | 1868.   | St. Paul’s Church,  | Much damaged     | Builder, xxvi.  |
  |  May    |  Little Chester,    |                  |  340            |
  |         |  Derby              |                  |                 |
  |         |                     |                  |                 |
  | 1868.   | St. Stephen’s,      | Slightly damaged | Builder, xxvi.  |
  |  June   |  Southwark          |                  |  433            |
  |         |                     |                  |                 |
  | 1868.   | Temporary           | Set on fire      | Builder, xxvi.  |
  |  June   |  Congregational     |                  |  433            |
  |         |  Church, Buckhurst  |                  |                 |
  |         |  Hill               |                  |                 |
  |         |                     |                  |                 |
  | 1868.   | Victoria Tower,     | Slightly damaged | Builder, xxvi.  |
  |  June   |  Houses of          |                  |  416            |
  |         |  Parliament         |                  |                 |
  |         |                     |                  |                 |
  | 1868.   | Morville Church,    | Much damaged     | Builder, xxvi.  |
  |  June   |  Shropshire         |                  |  416            |
  |         |                     |                  |                 |
  | 1868.   | School, Furze       | Much damaged     | Builder, xxvi.  |
  |  June   |  Hill, Brighton     |                  |  416            |
  |         |                     |                  |                 |
  | 1868.   | Church, Shanghai    | Destroyed        | Builder, xxvi.  |
  |  June   |                     |                  |  416            |
  |         |                     |                  |                 |
  | 1870    | St. Saviour’s,      | One pinnacle     | Builder,        |
  |         |  Southwark          |  destroyed and   |  xxviii. 604    |
  |         |                     |  church damaged  |                 |
  |         |                     |                  |                 |
  | 1870    | Rotherfield Church  | Considerably     | Builder,        |
  |         |                     |  damaged         |  xxviii. 604    |
  |         |                     |                  |                 |
  | 1871.   | Hethersett Church   | Much damaged     | Builder, xxix.  |
  |  June   |                     |                  |  450            |
  |         |                     |                  |                 |
  | 1871.   | St. John’s Church,  | Slightly damaged | Builder, xxix.  |
  |  June   |  Bury St. Edmunds   |                  |  450            |
  |         |                     |                  |                 |
  | 1871.   | St. Margaret’s      | Much damaged     | Ann. Reg. p. 72 |
  |  July   |  Church, King’s Lynn|                  |                 |
  |         |                     |                  |                 |
  | 1871.   | Cromer Church       | Damaged          | Ann. Reg. p. 72 |
  |  July   |                     |                  |                 |
  |         |                     |                  |                 |
  | 1871.   | Congregational      | Considerably     | Scientific      |
  |  Sept.  |  Church, Terre      |  damaged         |  American, xxv. |
  |         |  Haute, Ind., U.S.  |                  |  161            |
  |         |                     |                  |                 |
  | 1872.   | St. Mary’s Church,  | Set on fire and  | Builder, xxx.   |
  |  Jan.   |  Crumpsall,         |  destroyed       |  51             |
  |         |  Manchester         |                  |                 |
  |         |                     |                  |                 |
  | 1872.   | Baptist Chapel, Wem | Slightly damaged | Builder, xxx.   |
  |  June   |                     |                  |  511            |
  |         |                     |                  |                 |
  | 1872.   | St. Mary’s Church,  | Set on fire and  | Builder, xxx.   |
  |  June   |  Beeston, Norfolk   |  destroyed       |  423            |
  |         |                     |                  |                 |
  | 1872.   | St. Martin’s        | Slightly damaged | Builder, xxx.   |
  |  June   |  Church, Birmingham |                  |  423            |
  |         |                     |                  |                 |
  | 1872.   | Rainham Church,     | Damaged          | Builder, xxx.   |
  |  May    |  Kent               |                  |  391            |
  |         |                     |                  |                 |
  | 1872.   | Mashbury Church,    | Set on fire      | Builder, xxx.   |
  |  May    |  Essex              |                  |  391            |
  |         |                     |                  |                 |
  | 1872.   | Bampton Parish      | Much damaged     | Builder, xxx.   |
  |  May    |  Church             |                  |  391            |
  |         |                     |                  |                 |
  | 1872.   | Chiddingley Church  | Slightly damaged | Builder, xxx.   |
  |  June   |                     |                  |  484            |
  |         |                     |                  |                 |
  | 1872.   | All Saints’         | Slightly damaged | Builder, xxx.   |
  |  June   |  School, Little     |                  |  484            |
  |         |  Horton             |                  |                 |
  |         |                     |                  |                 |
  | 1872.   | Kibblesworth        | Slightly damaged | Builder, xxx.   |
  |  June   |  Wesleyan Chapel    |                  |  484            |
  |         |                     |                  |                 |
  | 1872.   | Brixton Church      | Considerably     | Builder, xxx.   |
  |  July   |                     |  damaged         |  603            |
  |         |                     |                  |                 |
  | 1872.   | Leigh Church        | Severely injured | Builder, xxx.   |
  |  July   |                     |                  |  591            |
  |         |                     |                  |                 |
  | 1872.   | St. Giles,          | Slightly damaged | Builder, xxx.   |
  |  Aug.   |  Cripplegate        |                  |  629            |
  |         |                     |                  |                 |
  | 1872.   | Holy Trinity        | Severely injured | Builder, xxx.   |
  |  Aug.   |  Church, Windsor    |                  |  610            |
  |         |                     |                  |                 |
  | 1872.   | Dundonald Parish    | Spire and roof   |                 |
  |  Sept.  |  Church             |  damaged         |                 |
  |         |                     |                  |                 |
  | 1873.   | Parish Church,      | Slightly damaged | Builder, xxxi.  |
  |  April  |  Cromer             |                  |  331            |
  |         |                     |                  |                 |
  | 1873.   | Martham Church      | Much damaged     | Builder, xxxi.  |
  |  April  |                     |                  |  331            |
  |         |                     |                  |                 |
  | 1873.   | Ripponden Church    | Much damaged     | Builder, xxxi.  |
  |  Nov.   |                     |                  |  875            |
  |         |                     |                  |                 |
  | 1873.   | Industrial School,  | Set on fire      | Builder, xxxi.  |
  |  Nov.   |  Mosbank, Glasgow   |                  |  875            |
  |         |                     |                  |                 |
  | 1874.   | Chesterfield Church | Slightly damaged | Builder,        |
  |  July   |                     |                  |  xxxii. 613     |
  |         |                     |                  |                 |
  | 1874.   | Christ Church,      | Slightly damaged | Builder,        |
  |  July   |  Salford            |                  |  xxxii. 613     |
  |         |                     |                  |                 |
  | 1874.   | St. Luke’s,         | Set on fire,     | Builder,        |
  |  July   |  Homerton           |  much damaged    |  xxxii. 613     |
  |         |                     |                  |                 |
  | 1874.   | General Post        | Slightly damaged | Builder,        |
  |  July   |  Office, St.        |                  |  xxxii. 613     |
  |         |  Martin’s le Grand  |                  |                 |
  |         |                     |                  |                 |
  | 1874.   | Military Prison,    | Slightly damaged | Builder,        |
  |  July   |  R.A. Barracks,     |                  |  xxxii. 613     |
  |         |  Woolwich           |                  |                 |
  |         |                     |                  |                 |
  | 1874.   | Free Church of      | Completely       | Builder,        |
  |  July   |  Braco, Perthshire  |  destroyed       |  xxxii. 613     |
  |         |                     |                  |                 |
  | 1874.   | Ayot St. Peter      | Completely       | Ann. Reg. p. 70 |
  |  July   |  Parish Church,     |  destroyed       |                 |
  |         |  Herts              |                  |                 |
  |         |                     |                  |                 |
  | 1875.   | Chester le Street,  | Spire            | Newcastle       |
  |  June   |  Durham             |  considerably    |  Chronicle,     |
  |         |                     |  damaged         |  June 16th      |
  |         |                     |                  |                 |
  | 1875.   | West End Church,    | Spire destroyed  | Builder,        |
  |  June   |  near Southampton   |                  |  xxxiii. 586    |
  |         |                     |                  |                 |
  | 1875.   | London and South    | Destroyed        | Builder,        |
  |  June   |  Western Railway    |                  |  xxxiii. 586    |
  |         |  Co.’s tall         |                  |                 |
  |         |  chimney shaft at   |                  |                 |
  |         |  Southampton        |                  |                 |
  |         |                     |                  |                 |
  | 1875.   | Barthomley Church,  | Damaged          | Daily paper     |
  |  July   |  near Crewe         |                  |                 |
  |         |                     |                  |                 |
  | 1875.   | St. Mary’s Church,  | Much damaged     | Builder,        |
  |  July   |  Birkenhead         |                  |  xxxiii. 632    |
  |         |                     |                  |                 |
  | 1875.   | St. Nicholas        | Much damaged     | Builder,        |
  |  Aug.   |  Church,            |                  |  xxxiii. 783    |
  |         |  Blundellsands      |                  |                 |
  |         |                     |                  |                 |
  | 1876.   | Cottingham Church,  | Set on fire      | Daily paper     |
  |  Mar.   |  near Hull          |                  |                 |
  |         |                     |                  |                 |
  | 1876.   | Snettisham Church   | Considerably     | Daily paper     |
  |  April  |                     |  damaged         |                 |
  |         |                     |                  |                 |
  | 1876.   | Shotts Parish       | Steeple          | Daily paper     |
  |  April  |  Church             |  destroyed       |                 |
  |         |                     |                  |                 |
  | 1876.   | Union Workhouse,    | Roof set on fire | Daily           |
  |  July   |  Retford            |                  |  Chronicle,     |
  |         |                     |                  |  July 25        |
  |         |                     |                  |                 |
  | 1876.   | Bishopstone Church  | Considerably     | Lloyd’s Weekly  |
  |  July   |                     |  damaged         |  News, July 23  |
  |         |                     |                  |                 |
  | 1876.   | Wilmcote Church     | Considerably     | Lloyd’s Weekly  |
  |  July   |                     |  damaged         |  News, July 23  |
  |         |                     |                  |                 |
  | 1876.   | St. Peter’s         | Considerably     | Sunday Times,   |
  |  July   |  Church,            |  damaged         |  July 23        |
  |         |  Stratford-on-Avon  |                  |                 |
  |         |                     |                  |                 |
  | 1876.   | Market Hall,        | Damaged          | Daily           |
  |  July   |  Doncaster          |                  |  Telegraph,     |
  |         |                     |                  |  July 24        |
  |         |                     |                  |                 |
  | 1876.   | Grey Friars Tower,  | Considerably     | Daily paper     |
  |  Sept.  |  King’s Lynn        |  damaged         |                 |
  |         |                     |                  |                 |
  | 1877.   | Catholic Church,    | Six persons      | Globe, May 31,  |
  |  May    |  Wieschen, Poland   |  killed and      |  1877           |
  |         |                     |  seventy         |                 |
  |         |                     |  seriously       |                 |
  |         |                     |  injured         |                 |
  |         |                     |                  |                 |
  | 1877.   | All Saints Church,  | Much damaged     | Builder’s       |
  |  May    |  Stand Whiteland,   |                  |  Weekly         |
  |         |  Lancashire         |                  |  Reporter, May  |
  |         |                     |                  |  25, 1877       |
  |         |                     |                  |                 |
  | 1878.   | Sir David Baird’s   | Almost entirely  | Daily           |
  |  May    |  monument,          |  destroyed       |  Telegraph, May |
  |         |  Perthshire         |                  |  30             |
  |         |                     |                  |                 |
  | 1878.   | St. Luke’s Church,  | Damaged          | Daily paper     |
  |  June   |  Hackney            |                  |                 |
  |         |                     |                  |                 |
  | 1878.   | Wesleyan Chapel,    | Damaged          | Daily paper     |
  |  July   |  Southampton        |                  |                 |
  |         |                     |                  |                 |
  | 1878.   | Free Methodist      | Damaged          | Daily paper     |
  |  July   |  Church, Tamworth   |                  |                 |
  |         |                     |                  |                 |
  | 1878.   | St. Jude’s Church,  | Much damaged     | Daily paper     |
  |  July   |  Bethnal Green      |                  |                 |
  |         |                     |                  |                 |
  | 1878.   | Church of the Holy  | Considerably     | The Times,      |
  |  July   |  Nativity, Knowle   |  damaged         |  July 27        |
  |         |                     |                  |                 |
  | 1879.   | Henlow Church,      | Considerably     | The Times,      |
  |  April  |  Bedfordshire       |  damaged         |  April 18       |
  |         |                     |                  |                 |
  | 1879.   | Laughten-en-le-     | Considerably     | The Times, May  |
  |  May    |  Morthen Church     |  damaged         |                 |
  |         |                     |                  |                 |
  | 1879.   | St. Marie’s         | Set fire to the  | Weekly          |
  |  June   |  Church, Rugby      |  woodwork        |  Dispatch, June |
  |         |                     |                  |  8              |
  |         |                     |                  |                 |
  | 1879.   | Clevedon Market     | Very much        | Daily           |
  |  June   |  House, nr. Bristol |  damaged         |  Chronicle,     |
  |         |                     |                  |  June 10        |
  |         |                     |                  |                 |
  | 1879.   | Parish Church,      | Burnt to the     | Norwich paper   |
  |  Aug.   |  Wells, Norfolk     |  ground          |                 |
  |         |                     |                  |                 |
  | 1879.   | Cromer Church       | Pinnacle damaged | Daily paper     |
  |  Aug.   |                     |                  |                 |
  |         |                     |                  |                 |
  | 1879.   | St. Bride’s         | Slightly damaged | Daily paper     |
  |  Aug.   |  Church, Stepney    |                  |                 |
  |         |                     |                  |                 |
  | 1879.   | Sanctuary of        | Damaged.         | Electrician,    |
  |  Sept.  |  Madonna de         |  Several persons |  Sept. 6        |
  |         |  Valmala, Valmala   |  killed          |                 |
  +---------+---------------------+------------------+-----------------+


_POWDER MAGAZINES STRUCK BY LIGHTNING._

  +-------+------------------------------+-----------------------------+
  | DATE  |           BUILDING           |           DAMAGE            |
  +-------+------------------------------+-----------------------------+
  | 1732. | Gunpowder Magazine at        | Exploded. City laid in      |
  |  Oct. |  Compost Major, Portugal     |  ruins; above 1,000 people  |
  |       |                              |  injured                    |
  |       |                              |                             |
  | 1739. | Bremen                       | 1,000 houses destroyed      |
  |  Sept.|                              |                             |
  |       |                              |                             |
  | 1763. | Fort Augusta, Jamaica,       | Great number killed; much   |
  |  Nov. |  powder magazine, containing |  damage to property         |
  |       |  2,850 barrels of powder     |                             |
  |       |                              |                             |
  | 1769. | Brescia Magazine, containing | Exploded; 3,000 persons     |
  |  Aug. |  207,600 lbs. of powder      |  killed                     |
  |       |                              |                             |
  | 1769  | Venice                       | 400 persons killed          |
  |       |                              |                             |
  | 1772. | Chester                      | Great damage to property;   |
  |  Nov. |                              |  many lives lost            |
  |       |                              |                             |
  | 1773  | Cambray                      | 18 people killed; several   |
  |       |                              |  houses greatly damaged     |
  |       |                              |                             |
  | 1773  | Abbeville                    | 150 persons killed; 100     |
  |       |                              |  houses destroyed           |
  |       |                              |                             |
  | 1780. | Malaga Gunpowder Magazine    |                             |
  |  Aug. |                              |                             |
  |       |                              |                             |
  | 1782. | Sumatra Gunpowder Magazine   |                             |
  |  Mar. |                              |                             |
  |       |                              |                             |
  | 1785. | Tangiers Gunpowder Magazine  |                             |
  |  May  |                              |                             |
  |       |                              |                             |
  | 1807. | Luxembourg Gunpowder Magazine| About 12 tons of powder     |
  |  June |                              |  exploded                   |
  |       |                              |                             |
  | 1808. | Venice Gunpowder Magazine    |                             |
  |  Sept.|                              |                             |
  |       |                              |                             |
  | 1829. | Navarino Gunpowder Magazine  | 17 killed; 78 wounded       |
  |  Nov. |                              |                             |
  |       |                              |                             |
  | 1840. | Bombay Gunpowder Works Dum   |                             |
  |  June |  Dum Gunpowder Magazine      |                             |
  |       |                              |                             |
  | 1843. | Sicily, Puzzaloni Gunpowder  |                             |
  |  April|  Magazine                    |                             |
  |       |                              |                             |
  | 1843. | Spain, Gaucin Gunpowder      | A number of persons         |
  |  April|  Magazine                    |  killed; church and 200     |
  |       |                              |  houses destroyed           |
  |       |                              |                             |
  | 1853  | Hounslow Gunpowder Magazine  |                             |
  |       |                              |                             |
  | 1855. | Firework manufactory,        | Exploded                    |
  |  Oct. |  Liverpool                   |                             |
  |       |                              |                             |
  | 1856. | Rhodes Gunpowder Magazine    | A considerable number of    |
  |  Nov. |                              |  persons killed, and a      |
  |       |                              |  large portion of the town  |
  |       |                              |  laid in ruins              |
  |       |                              |                             |
  | 1857. | Bombay, Joudpore             | About 1,000 persons         |
  |  Aug. |                              |  killed; 500 houses         |
  |       |                              |  destroyed                  |
  |       |                              |                             |
  | 1878. | Bruntcliffe Colliery, near   | Exploded                    |
  |  Aug. |  Leeds; powder magazine,     |                             |
  |       |  containing about one ton of |                             |
  |       |  powder                      |                             |
  |       |                              |                             |
  | 1878. | Pottsville, Pa., U.S.; a     | Exploded; 3 persons         |
  |  Aug. |  powder magazine containing  |  killed, several injured;   |
  |       |  25,000 lbs. of powder       |  many houses wrecked        |
  +-------+------------------------------+-----------------------------+




CHAPTER XV.

THE EARTH CONNECTION.


To dwell too largely upon the importance of leading all lightning
conductors down into moist earth, or, as technically called, ‘good
earth,’ would be scarcely possible. It would perhaps not be too
strong an expression to say that the part of the conductor above
ground is a mere appendage to that under ground, the essential
function of the whole apparatus--that of dispersing the electric force
harmlessly--being accomplished by the subterranean portion. The clear
understanding of Benjamin Franklin perceived this at the outset;
but after him it seemed as if forgotten for a long time, and the
result showed itself in numerous disasters that occurred to buildings
protected with conductors, which brought the latter into disrepute with
many persons. While, no doubt, in many instances the cause of these
disasters was in the bad application of the conductors themselves,
their defective character, or their feebleness, still in the great
majority the underground connection may be taken to have been in
fault. It may be laid down as an absolute certainty that a really good
conductor--say, a copper rope from five-eighths to three-quarters of an
inch in thickness--cannot possibly fail to carry off the electric force
if the lower part reaches moist earth or water. Probably, in nine cases
out of ten, whenever a building provided with a conductor is struck by
lightning, it is for want of ‘good earth.’

Franklin’s own ideas were very clear on the subject. He laid them
down at various times, more particularly when residing in England,
during the years from 1764 to 1775, as colonial agent for Pennsylvania.
During the latter part of this period he took an active interest in the
proceedings of the Royal Society; and this learned body being requested
by the Government to give advice regarding the best protection against
lightning that could be provided for the great powder magazines at
Purfleet, he was nominated into a committee with three other members,
William Watson, H. Cavendish, and J. Robertson. The committee drew up
a report, dated August 21, 1772, signed by all the members, but known
to be written by Franklin alone. Dwelling strongly on the importance of
the underground connection, Franklin says in this report: ‘In common
cases it has been judged sufficient if the lower parts of the conductor
were sunk three or four feet into the ground, till it came to moist
earth; but this being a case of great consequence, we are of opinion
that greater precaution should be taken. Therefore we would advise that
at each end of each magazine a well should be dug, in or through the
chalk, so deep as to have in it at least four feet of standing water.
From the bottom of this water should rise a piece of leaden pipe to, or
near, the surface of the ground, where it should be joined to the end
of an upright bar.’ Franklin then goes on to recommend the usefulness
of having even more wells than the two, so as to avoid any possibility
of failure in protecting the powder magazines. ‘We also advise,’ he
says in his report, ‘in consideration of the great length of the
buildings, that two wells of the same depth with the others should be
dug within twelve feet of the doors of the two outside magazines--that
is to say, one of them on the north side of the north building, and the
other on the south side of the south building, from the bottom of which
wells similar conductors should be carried up.’ It is not on record
whether these recommendations were adopted by the Government, but it
seems likely that this was the case, as the fear of explosion of powder
magazines through a stroke of lightning was very great at the time. Not
long before, a magazine had been so destroyed at Brescia, in Italy,
with the appalling result of a considerable part of the city being laid
in ruins, burying many hundreds of persons. The destruction of the
Brescia powder magazine, like all similar events, had, it is scarcely
necessary to say, its due effect in spreading a desire for lightning
conductors, fear doing what was not effected by foresight.

Whether or not the English Government made the wells recommended by
Franklin for the Purfleet powder magazine, it is certain that the
sound advice given was not largely followed. On the contrary, there
grew a generally prevailing laxity in regard to the indispensableness
of a good underground connection, which led to numerous accidents.
They were seldom, however, ascribed to the right cause, others being
sought instead--such as particular forms of conductors and the
insufficient length of those phantoms called ‘reception-rods,’ which,
as many thought, could never be made high enough, in order to ‘draw
the electric fluid’ from the clouds. Height was sought where nothing
but depth was required, and the same unsightly rods, towering high
above buildings, would have very effectually carried off the electric
forces if brought from the top to the bottom of the conductor, being
taken out of the air and stuck into the earth. Still, there were
not wanting philosophical minds impressed with the truth that no
lightning conductor can discharge its functions unless rooted in
moisture, and who not only knew it, but did their best to spread this
knowledge in all directions. One of these philosophers, a singular
character in his way, was a German clergyman, the Rev. Dr. Hemmer,
who lived at Mannheim, on the Rhine, at the end of the last century.
Taking the deepest interest in Franklin’s great discovery, he made
many experiments with lightning conductors, which brought him to the
conviction that the electric force, in its chief tendency, seeks
the mass of water on the globe, and that where this is not on the
surface, it must be guided to it to become harmless. Consequently, he
recommended to sink the conductor invariably deep into the ground, so
as to reach water, and to subordinate everything else to this prime
necessity. To make the use of lightning conductors as general as
possible, Dr. Hemmer not only wrote a number of little books, which
he liberally distributed, but travelled about through many parts of
Germany, instigating the authorities to place conductors on all public
buildings, and the people to set them up over their own houses. Holding
that the earth connection was everything, he advocated simply to dig
a hole in the ground till water or very moist earth was reached, and
to stick a small iron bar, wrapped in lead to prevent rust, into it,
running up the roof. The bar any village blacksmith could forge, and
the hole any man or boy could dig, thus making the absolute cost of the
conductor under this arrangement very trifling. Dr. Hemmer was right,
no doubt, in his main argument, and most successful in spreading the
knowledge of lightning conductors, while he was able to boast that not
one of all the number he had set up had ever failed. However, he lived
in an age when as yet water and gas pipes were unknown, and iron, or
any other metal, scarcely entered into the construction of buildings.
Given a leaden roof and a network of metal tubes, and Dr. Hemmer’s
small iron rod could scarcely be expected to do its work of protection.

Together with Dr. Hemmer in Germany, Professor Landriani, of Milan,
drew attention to the paramount importance of a perfect earth
connection. He made it his special business to investigate cases in
which buildings with lightning conductors had been struck, and was able
to show in nearly every instance that it had been for want of ‘good
earth.’ A very striking case, which ought to have brought conviction
of the truth to all investigators of the subject, occurred in Genoa in
1779. The church of St. Mary in this city, standing in a very elevated
position, had been frequently struck by lightning, sometimes as often
as twice in one year, and it was noticed that the electric force always
followed precisely the same path, running along a certain portion
of masonry, partly secured by iron hoops, and finally demolishing a
wall at the bottom to get into the earth. At last, in November 1778,
a conductor, made of the most approved design, was placed over the
church, but, to the great surprise of the scientific men who had
superintended the work, the lightning fell once more upon the building
in the month of July of the following year, again following the old
path it had constantly taken before, and causing absolutely the same
damage as previously, even to the knocking out of certain portions of
the wall nearest the ground. Naturally, the event caused widespread
interest, leading to the closest examination of the church of St. Mary
by several experts, among them Professor Landriani. He had no great
trouble in discovering both the causes of the path of the lightning
having always been the same when falling upon the church, and of the
edifice having been struck again in the same manner when provided with
a lightning conductor. Being a somewhat peculiar structure, consisting
in part of hewn stones held together with iron cramps, there was a
large quantity of metal both in and outside; and it was found that
the path of the lightning had always been precisely in the direction
where the metal offered the greatest continuity, leaping over the short
intervals that existed by destroying the stone, and finally getting
into the ground to a place where there was always a collection of
water by knocking down a wall. If this accounted satisfactorily for
the former accidents, that which took place when a conductor had been
placed was not much more difficult of explanation. Professor Landriani
found that though the conductor itself was very good, it was useless
simply by having its roots in hard rock instead of moist ground. On
the one side of St. Mary’s Church there was a rill of water rippling
down from the hills, and forming a small pool near the church, while
on the other was the hard rock. It was into a crevice of the latter
that the conductor had been laid, thus leaving the electric force to
seek its old path into the water along the iron bars, which, although
disjointed, formed a far better road to earth than the planned road.
It was a convincing proof of the supreme necessity of a good earth
connection. Still, a long time yet was to elapse before conviction
became general.

Probably, the matter was more studied by Italian scientific men than
any others, the study of electricity having always been a favourite
pursuit in that country; yet there, too, the matter was not understood
till quite recently. This is proved by a letter of the celebrated
astronomer and meteorologist, Father Secchi, addressed to the French
scientific journal ‘Les Mondes,’ in October 1872, in which he tells
the story of an accident that befel a building protected by lightning
conductors set up under his own direction, the earth connection being
made after rules laid down by Professor Matteucci, considered the
leading authority on the subject. The letter of Father Secchi, though
of some length, is given here entirely, both on account of the great
fame of the writer, but recently deceased, and because it throws a
flood of light on some of the most important points connected with the
art of designing and applying lightning conductors.

‘Eight years ago,’ says Father Secchi, writing, as just mentioned, in
1872, ‘some lightning conductors had been erected under my direction
on the cathedral and on the Bishop’s palace of Alatri, situated at
the summit of the Acropolis of that town, which, by its elevated and
solitary position, was exposed to frequent ravages from storms. It was
not long ago that a flash of lightning demolished a great part of the
belfry, and damaged the organ of the church. In the erection of this
lightning conductor there arose a great difficulty proceeding from the
nature of the soil, which at the depth of some centimetres turns out to
be entirely of solid calcareous rock.

‘In order to remedy this defect, that part of the conductor which
enters the ground has been made very long, more than 4 metres [13
feet], and has been provided with a great many couples of points, 5
centimetres [2 inches] broad, 5 millimetres [⅛ inch] thick, indentated
on the edges, with the addition of a thick copper wire twisted among
the same points, to help to multiply the points of contact between the
rod and the carbon. The foot of the lightning conductor is entirely
of copper. The rod is also of copper up to a metre [3¼ feet] above
the ground; and there is joined to it the iron conductor, in the
ordinary receptacle made in the heart of the wall, to preserve it from
disturbances of the inferior parts. The ditch into which the foot of
the lightning conductor was sunk is 5 metres [·16 feet] long, and
half-a-metre [1⅝ feet] wide, and it was dug into the ground as far
as to touch the roots of some neighbouring trees, from which point
upwards a layer of cinders was placed, covering the greater part of the
ditch. Thus the surface of contact between the metal and the carbon,
and of the latter with the soil, was such that one would have supposed
it to be more than sufficient, while the presence of trees, although
they were not very large, made it highly probable that the ground did
always contain sufficient moisture. Moreover, as the edifice had two
culminating points--namely, the belfry and the raised back portion of
the choir--two rods were placed on them, each having an independent
connection with the earth, so that, in the case of a discharge on one
of the points, the electric force might find two ways in its course
towards the earth.

‘These arrangements produced, on the whole, a good result, since,
although the edifice was struck at least four times after conductors
had been placed on it, it suffered no damage of any kind. Nevertheless
a very curious accident, highly interesting as a scientific study,
happened on October 2. Early on the morning of this day several flashes
of lightning fell down from the clouds during a terrific storm,
which lasted over two hours. The belfry was struck at first by weak
discharges twice; but the third flash was so appalling in its strength
as to terrify the whole town below. The injuries it caused were not
great, still they seemed to me to be extremely noteworthy. But before
I describe them I must give some necessary details as to place and
position of the lightning conductor.

‘It so happened that four years after the erection of the conductor
a line of pipes was laid down to carry water to the towns of Alatri
and Ferentino, passing at a short distance from the belfry of the
cathedral. The lightning conductor was not placed in communication with
the pipes, because it seemed established, from previous experiments
and observations, that it was needless to do so, the ground containing
apparently sufficient moisture, the head of the waterworks being close,
and there existing also a running fountain. I was not asked at the time
whether it was necessary to establish this communication, but, had the
question been put to me, I should probably have answered it in the
negative, considering, from what I then knew, the work as superfluous.
That I was in error then as to the necessities of a perfect underground
connection is shown by what happened during the great storm in the
early morning of October 2. The heavy flash of lightning before
referred to did not go its appointed path underground, but passed off
into the waterworks, with the following results:—

‘1. It made in the earth a perfectly rectilinear excavation, which,
from the lower part of the conductor, went to the tube of the
waterworks running to Ferentino, and in traversing the wall destroyed
the angle of that structure. The earth of the ditch thus dug was
disposed regularly to right and left with great symmetry. The length
of the ditch was about 10 metres, the depth about 70 centimetres [28
inches].

‘2. The lightning struck the water-pipe of Ferentino, broke it
completely, throwing the pieces to a distance of about 80 centimetres
[32 inches]. The lead which soldered the joint of the broken tube with
the tube beyond was found melted. In consequence of this rupture the
water ceased flowing to Ferentino, and poured into the waterworks.

‘3. Another part of the discharge spread itself by the pipe which goes
to Alatri, and traversing the reservoir threw to a great distance
some wooden plugs which stopped up the discharging tubes, the plugs
being forcibly hammered in. It arrived at the town in a tank, where it
damaged and twisted in a strange manner a leaden slab which was in the
tank, made some other little injuries, and finally left the trace of
its passage at the spouts of the public fountain.

‘4. The point of the lightning conductor was examined, and it was found
very blunt; it was found impossible to unscrew it, and it could not be
removed without breaking the screw. It was found broken to a length of
more than 3 centimetres [1¼ inch], and the section of fusion was nearly
flat, as though it had been cut. The gold of the gilding had nearly all
disappeared. In the church, and in the edifice which is attached to
it, no injury was detected. These facts appear to me important both as
regards practice and theory: in respect to theory, because they give
an idea of the quantity and of the immense force of the discharge.
The melting of the point down to a section 1 centimetre [½ inch] in
diameter proves that it would have been melted down much further if it
had been slighter. It is not prudent, then, to use very slender points;
it is best that they should thicken quickly.

‘The excavation of the ditch at the foot of the lightning conductor
could not be the direct effect of electricity, but would be the result
of the sudden evaporation of the moisture of the ground, generating
steam, and forming, as it were, a mine.

‘The breaking of the tube is most singular. It seems to me that it
can with difficulty be attributed to the mechanical shock of the
electricity itself. As the lead which united the broken tube to the
one beyond was found melted, it is evident that, in spite of the water
which flowed in this tube, it was raised to an enormous temperature in
the place where it was struck, and probably it was the instantaneous
evaporation of the water inside which caused the breaking of the tube.

‘But the most singular fact, in a certain respect, is what was observed
in the tube which descends to Alatri--that is to say, the alteration
in form of the leaden slab. The little interruption which necessarily
exists in this tank between the conducting-pipe and the metallic
receptacle evidently gave occasion for a discharge by a flash, and, in
consequence, for an explosion of steam. But we see at the same time
by that that the distance traversed in the tube from the building to
the slab, a distance of more than 200 metres [650 feet], in which the
pipe is buried underground, did not suffice for the charge to lose
itself in the ground, although during the passage it had to cross the
reservoir, and might there have distributed itself. Our surprise is
still greater when we reflect that it was only part of the discharge,
since the greater portion had to flow by the water-pipe of Ferentino,
which was the first struck in a direct manner, and that these pipes
are joined together with lead. The quantity of electricity must have
been enormous, in order to be able to have so much force and to run
another 300 metres [975 feet] to reach the public fountain, and leave
its traces there. A circumstance which deserves attention is, that this
storm took place after a long and constant drought; and consequently
the earth was less moist, and could offer little facility for
dispersion.

‘These cases are not so rare among us as one might suppose. Not very
long ago, at Lavinia, a flash of lightning destroyed a great part of
the belfry, passed to the bell, broke and melted it in its passage in
such a manner that the metal had run away like wax. I do not believe
this breakage of the bell to have been a mechanical effect of the
lightning in a rigorous sense, for the bell could have been broken by
the instantaneous expansion produced by the heat at the point of the
passage, an expansion which had had no time to disperse, as a glass
vase breaks when touched with a red-hot iron.

‘Let these facts come about how they may, they enable us to see that it
is necessary to devote great attention in the erection of lightning
conductors, that we must allow them a large surface for discharge, _and
that there can never be too much of it_. The surface of the foot of
our lightning conductor was certainly superior to what has been judged
sufficient by Matteucci for the discharges of telegraphic conductors,
and yet it has not sufficed. Further, it is a confirmation of the
necessity of making the neighbouring metallic masses communicate, and
especially with water and gas-pipes.’

From out of the almost endless number of cases in which lightning
conductors failed for want of a good earth connection, another one or
two may be given, illustrated as having happened quite recently in
England, and as such showing, in a very striking manner, in what a
neglected state the knowledge of the subject still is at this moment.
A thunderstorm passed over the town of Clevedon, Somersetshire, in the
afternoon of March 15, 1876, and a flash of lightning fell upon the
steeple of Christchurch, provided, as was generally thought, with a
most efficient conductor of recent construction, made of good copper
rope. What happened is graphically and minutely told in a letter
addressed to the ‘Journal of the Society of Telegraph Engineers,’ by
Mr. Eustace Buttor, of Lewesfell, near Clevedon. ‘There was but a
single flash,’ Mr. Buttor relates, ‘which appeared to many observers
to travel horizontally through the air. However, the lightning passed
down the lightning conductor of Christchurch. The flag-staff, about
100 feet high, and the four pinnacles, about 90 feet high, have each a
conductor, the flag-staff having the usual conical point, the pinnacles
having the copper rope attached to their vanes. The five copper ropes
unite inside the tower in the neighbourhood of the clock. Lower down
the conductor passes through a slanting hole to the outside, and for
the lowest 12 feet is encased in a pipe. On reaching the ground it
passes into a dry freestone channel for about a dozen feet, and then
dips down into the drain which carries rain-water from the roof. As no
rain preceded or accompanied the flash, it may be presumed that _the
drain was dry_.

‘The protector is copper throughout, and, with the exception of the
termination, seems to have been carefully and efficiently placed.
The diameter I estimate to be half-inch, or it may be a trifle more.
Just at the point where it leaves the pipe and enters the ground, the
electric charge left it, dashed through three feet or more of solid
wall supporting the tower, in order to reach the gas-meter inside, then
it passed safely along the gas-pipe. The cavity made was considerable,
but very irregular. I was unable to ascertain when the workmen were
engaged in repairs, and therefore cannot give their estimate of the
weight of stone displaced, but it must have been many hundredweights,
though only a few pounds were actually thrown out on to the path, or
inside into the vault. A large quantity of stone was pulverised, and
the whole gave one the idea of the explosion of a charge of gunpowder
under great compression. In a house about 100 yards from the church,
the inmates felt the shock intensely, but did not know that the house
had been touched. Some hours after, however, on going to turn on the
gas, a hissing noise was heard, and a hole was found in the composition
gas-pipe, about five-eighth inch diameter, just where the pipe passed
within an inch of a water-pipe. The lightning must have come along
the main from the church gas-pipe to this house, and then passed to
the water-pipe as the readiest way to moist earth. The whole soil in
the neighbourhood is mountain limestone, very dry. There is not the
slightest evidence of displaced plaster, or any other sign of the
passage of an electrical discharge through the house.’ There need be
little comment on the facts stated in this letter, notable though they
are. It is the old delusion that a lightning conductor need be brought
down underground only, and that then all is right. In this case, those
who protected Christchurch, Clevedon, thought it quite sufficient to
bring the conductor down into a drain-pipe carrying rain-water from the
roof, without reflecting for a moment that an earthenware drain-pipe
would insulate the conductor from ‘earth.’ A similar instance came
under the writer’s notice about a year ago. One of the pinnacles
of Cromer Church, in Norfolk, was struck by lightning, although
fitted with a conductor on one of the pinnacles. On examination it
was discovered that the earth terminal had been inserted into an
earthenware drain.

It is not very easy to give exact prescriptions as to the best manner
in which the underground connection should be effected. The means
vary entirely with the circumstances, and the matter should in all
cases be intrusted to an expert. Simple as is the whole theory of
lightning protection, consisting in nothing else but laying a good
metallic path from the top of a building down into moist earth, as an
unfailing path for the electric force, the practical execution of it
is not the less often very complicated. It is especially so as regards
the most important of points, that of the underground connection. Of
course, wherever there is running water at hand, a river, or even a
tiny stream that never dries, the matter is easy enough, but as in the
great majority of buildings to be protected such water does not exist,
the solution of the question becomes more difficult, and frequently
one of the greatest perplexity. It tends even to be more and more so
in consequence of the progress of sanitary arrangements under which
towns and villages are ‘drained’ until the soil has been made as dry
as a rock. Immense as the benefit is to public health, it is, like all
benefits, attended by certain drawbacks. One of these certainly is a
greater danger from lightning. It is often proposed by builders to
use the drain-pipes themselves in making ‘good earth’ for lightning
conductors, but the fallacy of this recommendation need scarcely be
exposed, seeing that these conduits are generally made of earthenware,
as happened when Christchurch, Clevedon, was struck by lightning.

While broad rules cannot be laid down, still it may be affirmed that a
good earth connection, sufficient to carry off the heaven’s electric
discharges, may always be obtained by either of two means. The first,
and in all cases most preferable, is to lay the conductor deep enough
into the ground to reach permanent moisture. When this exists in a
considerable mass, the single conducting rope, touching it, will be
quite sufficient; but when the quantity is deficient, or doubtful, it
will certainly be advisable to spread out the rope, so as to run in
various directions, similar to the root of a tree, likewise in search
of moisture. There are various modes of accomplishing this, shown in
figs. 46 and 47.

[Illustration: Fig. 46.]

[Illustration: Fig. 47.]

A variety of methods have been proposed for the dispersion of the
electric force underground where the soil contains little or no
moisture, except at great depths, to be reached only by a vast amount
of labour and expenditure. In France, the system most generally adopted
in these cases is to place at the bottom of the underground connection
an apparatus, made either of iron or copper, shaped somewhat in the
form of a harrow, and to embed it thickly in charcoal. Fig. 48 will
illustrate this system of earth connection.

[Illustration: Fig. 48.]

The apparatus is as simple as it may be useful, and the more so, of
course, the thicker the mass of charcoal in which it is embedded. But
it may be doubted whether it is sufficient to make ‘good earth’ under
all circumstances. Perhaps it will do so in ninety-nine cases and fail
in the hundredth. The amount of electric force discharged in ordinary
thunderstorms does not seem to vary much, and, according to all
observations, such an artificial connection as this of the charcoal bed
is sufficient to disperse it safely beneath the surface. But now and
then there come storms of extraordinary violence, or, in other words,
extraordinary accumulations of atmosphere electricity, which demand
precautions such as are not fulfilled by the subterranean harrow,
however thickly embedded in charcoal, or, as oftener done, in gas coke
or cinders. It is certain that there have been cases in which buildings
with otherwise excellent conductors, but provided with such an
artificial earth connection, have been damaged by lightning. However,
it may be stated, as the net result of all observations and known facts
upon the subject, that small private houses can be well protected by
this means against lightning, but that the system cannot be recommended
as absolutely safe for large edifices and public buildings.

To protect any structure of great extent, it is absolutely necessary to
bring the conductor, or conductors, deep enough into the earth to reach
water. It is all the more indispensable with modern buildings, as they
contain large masses of metal, not only in gas and water-pipes, but
often in staircases and iron columns, towards which the electric force
has the strongest tendency to direct itself unless drawn to the earth
by an immediate and unfailing connection with the great sheet of water
below its surface. It is considered by German electricians that there
is no necessity, if a large edifice has a number of conductors, to let
each have a separate earth connection; it is quite sufficient to bring
them all into one, provided only that this is absolutely perfect at all
seasons and under all circumstances. Fig. 49 will show how this can be
done.

[Illustration: Fig. 49.]

It will be seen that for the protection of this edifice there are six
conductors, with four elevated points marked A, B, C and _c_. Two of
these points, A and C, expand from the roof to the ground into double
conductors, so as to protect the sides of the building against possible
lateral discharges of lightning, and all the six conductors meet a
little below the surface in the earth connection prepared for them. To
form this one connection, either by digging or boring, may sometimes
be costly, but whether the expenses be more or less, the protection
against lightning thus effected will be so absolute as to be invaluable.

In a similar manner as the large edifice, with its many gables, a
church may be fitted with lightning conductors. Fig. 50 scarcely needs
much explanation.

[Illustration: Fig. 50.]

There is one thing, however, regarding churches, that must be well
borne in mind in establishing their protection against lightning.
Besides containing great masses of metal, in bells, organs, and other
contents, they are frequently placed in high situations, exposed to
the most violent discharges of the electric force. It often happens
also that they stand on rocky ground, with the subterranean waters
far below the surface. To ensure absolute protection under these
circumstances, it is indispensable to connect the conductors with
water, wherever it is to be found, by a solid channel, into which
the copper rods may run, if possibly some distance below the surface
of the earth. The form such a channel may take is indicated on the
engraving. It will be seen that the protection against lightning
indicated here is not only for the church, but the adjoining parsonage,
the conductors spreading over both, with points on the most prominent
and exposed places. It would be possible to carry out this principle
in ensuring the protection of a whole block of private buildings.
German electricians think that one channel or well, sufficiently broad,
leading from the surface of the earth to layers always moist, or to
perennial springs, would suffice to carry the electric force discharged
upon a hundred conductors, and all the easier as it would be impossible
that many would be struck at one and the same time by lightning.
Perhaps some such arrangements will be made in the future, when both
houses and towns are built upon a more systematic plan than is followed
at the present time.

If, as a rule, one channel of underground connection is amply
sufficient for the protection of even the largest buildings, there
may be cases in which it is indispensable to spread the conductors
into several directions. It may be laid down, broadly, that when
there is water to be reached, the one channel is sufficient, but that
when this is not possible, or expedient, more lines of underground
connection must be formed. Fig. 51 may serve to illustrate a case of
the latter kind. It shows a powder-magazine, partly above and partly
underground, standing on dry soil, with trees in the neighbourhood,
likely to add to the danger of atmospheric discharges of electricity,
and with no stream, or permanent moisture, into which to guide them.
Nothing remains, under these circumstances, to ensure safety, but to
multiply the lines of underground connection to the utmost extent. To
add to the facility of the dispersion of the electric force, the main
channels may be filled with charcoal, broken coke, or cinders, and if
large quantities of these substances can be placed in one or two pits,
it is possible to make thus an artificial connection as nearly as can
be responding to ‘good earth.’ Still, it must never be forgotten that,
absolutely, ‘good earth’ in reference to lightning conductors means
moisture, or water.

If permanent moisture cannot be obtained and iron water-mains are
within reach, it is desirable to connect the ground terminal with them
by means of good solder, as from the large mass of metal they generally
form very good ‘earths.’

[Illustration: Fig. 51.]

In giving directions, or rather suggestions, about the design and
application of conductors, and, what is most important in regard to
them, their connection with the subterranean mass of waters, the
idea that persons may construct their own conductors is left aside
altogether as absurd. It is a good old proverb which says that a man
who is his own lawyer is certain to lose his cause; another has it
that a man who is his own doctor is sure to succumb to his illness.
With regard to the setting-up of lightning conductors, it is precisely
the same. Simple enough as is the theory of ‘drawing lightning’ from
the clouds, the practical execution of it is, as mentioned more than
once, not a little complicated. The formation of the underground
connection, in particular, is a matter requiring very great experience,
and very frequently one of the utmost difficulty. Vast sums of money
are often thrown away needlessly in making a connection which in the
end proves useless, while, on the other hand, a trifling addition to
the expenditure in setting-up a conductor would procure its efficiency,
not attained simply from want of ‘good earth.’ A recent writer on
lightning conductors whimsically, yet with much truth, expresses it by
remarking that ‘people spend money upon gilded points on the top of
the house, while they ought rather to sink it in water at the bottom.’
Undoubtedly, the efficiency of conductors lies, even more than at the
top, on ‘the bottom.’ The earth connection may be called ‘the alpha and
omega’ of lightning protection.




CHAPTER XVI

INSPECTION OF LIGHTNING CONDUCTORS.


There is one subject in regard to the proper protection of buildings
against the destructive effects of lightning which is generally
overlooked, at least in this country, to a really surprising degree.
It is the necessity that lightning conductors, once put up, should be
regularly inspected, to see if they are in good order, so as to be
really efficacious. That this is very rarely done, is one of the main
reasons why accidents by lightning sometimes occur in places nominally
protected by conductors. The neglect is the more astounding, as one
would think that all intelligent persons, whose knowledge prompted them
to see the wisdom of protection against lightning, would likewise come
to the conclusion that the scientific apparatus set up to effect it
required occasional repairs, such as the clocks in their houses and the
buildings themselves. But such is very far from being the case. It is,
perhaps, not too much to assert that at present not one in a thousand
persons who have gone to the expense of protecting their houses by
lightning conductors make the protection complete, at a merely nominal
cost, by providing a regular--say, annual or bi-annual--inspection.

The causes which necessitate such inspection are numerous. In the first
instance, there is the constantly acting influence of wind and weather
upon those parts of the conductor which are above earth. Wonderful
as is the simple machinery devised by Franklin which conducts the
mysterious electric force from the clouds into the ground, depriving
it of its destructive power, it is, after all, but a feeble thing in
itself, and necessarily so. The upper terminal of the conductor--what
the Germans call the ‘reception rod,’ and the French the ‘tige,’ or
stem--cannot be very thick without becoming unsightly, and, as regards
large public buildings, destroying their architectural effects; while
the rope, or ribbon, running to the ground must, for the same reason,
as well as that of cost, be of comparatively small diameter. Subject
to the constant effects of moisture, to wind, and ice, and hailstorm,
there is always a possibility of the slender metal strips being
damaged, so as to interrupt their continuity, and thus destroy the
free passage of the electric force. Instances have happened in which
the damage done was so slight as to be scarcely visible, and still
sufficient to destroy the efficacy of the conductor. Nothing but the
regular testing by a galvanometer--one of which is described, with an
illustration, on page 60--by an experienced person can establish the
fact that the action of the conductor remains perfect.

A second important cause for inspection lies in the necessity of always
ascertaining with accuracy whether the earth connection is really in a
faultless state. The immense significance of the earth connection--the
basis, in more than one sense, of lightning protection--having been
dwelt upon in the preceding chapter, it is only necessary here to
state that, even if perfectly secured at the outset, it is liable
to disarrangements. One not infrequent accident causing them is a
change in the soil from moisture to dryness, which may be brought
about either by altered drainage or long absence of rain. The dangers
which threaten a break in the earth connection by altered or improved
drainage are of the most serious kind, and likely to become more so
from year to year. Not only the soil of our towns and cities, but even
that of our villages, and the fields themselves, is getting ever more
honeycombed by drain-pipes, until almost every drop of moisture is
sucked out of the ground. No doubt the pipes themselves may improve the
earth connection, if of iron or any other metal. But very frequently
they are of earthenware, in which case they are far more dangerous
than useful, even if filled with water. To guard against the danger
likely to arise from changes in the drainage, it would be wise to have
a thorough examination, by means of the test galvanometer, of all
lightning conductors near to or affected by alterations in the drains,
whenever completed. The same recommendation may be made as regards
cases where the soil has become unusually dry after a long absence of
rain. Few persons, except those who have made a study of the subject,
can form an idea to what depth such dryness often extends, more
especially in sandy and gravelly soils.

There is a third ground, as material for consideration as each of the
two preceding ones, upon which the regular inspection of lightning
conductors must be strongly urged. It is, that constant alterations
in the interior of buildings, private residences as well as public
edifices, may serve to destroy the efficacy of a conductor which was
originally good, even to perfection. Thus a roof may be repaired, and
lead or iron introduced where it was not before; or clamps of iron may
be inserted in the walls of houses, to give them greater strength;
or, in fact, any changes may be made which bring masses of metal more
or less in proximity to the conductor. Under such circumstances, the
efficacy of the conductor is destroyed just in proportion as the
metal forms a better path for the dispersion of the electric force
than the one artificially prepared. There are hundreds of instances
to prove that changes made in buildings, such as the addition of a
leaden roof without, or the iron balustrade of a staircase within,
diverted the current of the electric force from the conductor on its
way to the earth, originally well provided for. In one rather curious
case, which happened at Lyons not many years ago, even an alteration
of the fixtures of a house proved destructive to the efficacy of a
conductor, perfect at the outset, the latter fact being shown in
that it had previously received a stroke of lightning and brought it
harmlessly to earth. The case was that of a banker possessed of the
piece of furniture indispensable to his profession, namely, a large
iron safe. It stood at first near an inner wall, in the centre of the
house; but wishing to add to its strength in resisting the attack of
burglars, the banker had it embedded partly in another wall adjoining
that on the outside, near a place where the masonry was held together
by some large iron clamps. In delightful ignorance of the effect of
this removal of his safe inside the house upon the lightning conductor
outside--an ignorance which would have been the same, probably, among
999 persons out of 1,000--the banker sat quietly down to dinner with
his family one day in July, when a terrific shock made the whole house
tremble to its foundations, upsetting furniture and breaking glasses.
The idea of an earthquake naturally came up at once; but when looking
out of the window (shivered to pieces) the banker was told by a crowd
assembled outside that there had been no earthquake, but that his house
had simply been struck by lightning, as it had been before. But while
previously the electric force had passed silently into the ground,
unknown even to the inmates of the house, and its passage verified
only by the accidental observation of a neighbouring meteorologist,
it had this time left its appointed path, seeking a new road more
strongly attractive. The lightning had found its way into the banker’s
safe, filled with gold. Once inside, the electric current, not finding
a farther outlet, had expended its force in shattering the walls
and making the house tremble, besides melting some gold and burning
banknotes. The investigation of the case at the time made some noise,
but it had one most useful result--it led to the institution of a new
office in connection with the Department of Public Architecture of the
city of Lyons, that of an inspector of lightning conductors. He was
charged to examine at stated intervals, or as often as circumstances
seemed to require it, the conductors applied to all the public
buildings of the city, to ascertain their efficacy, and, if not deeming
them in good condition, to effect all necessary repairs. Shall we
repeat, again and again, ‘They manage things better in France’?

The regular inspection of lightning conductors, as yet unknown or
all but unknown in England, has been for a long time in practice in
several States of Continental Europe, among them Germany and France.
The origin of such inspection may be traced to Northern Germany. It has
been mentioned before (Chap. IV., page 43) that the first lightning
conductor set up over a public building in Europe was erected on the
steeple of the Church of St. Jacob, Hamburg, and that the extension
of conductors in the city and neighbourhood was so rapid, that before
five years had gone by there were over seven hundred conductors. ‘To
this day they are comparatively more numerous in this district than
anywhere else in Europe.’ To this day, too, the scientific aspect of
the question of lightning protection, and the statistics connected with
it, are more appreciated here, and have been more closely investigated,
than in any other part of Europe. In recent years, this has been more
particularly the case in the territories to the north of the city of
Hamburg, the German province of Schleswig-Holstein. Not even in the
country of their origin, and the one which, as yet, has the greatest
number of them in use, have the ‘Franklin rods’ given rise to so much
serious study as in that part of Germany.

Thunderstorms are more numerous, on the average, in Schleswig-Holstein
than in any other part of Central and Northern Europe--due, probably,
to the fact of the province not only being a narrow peninsula, with the
Baltic on the east, and the German Ocean on the west, but intersected
by rivers and canals, producing a generally moist atmosphere. Almost
all public edifices in the province, and the great majority of private
buildings above the rank of mere cottages, are protected by lightning
conductors; and to aid in their extension there are special laws under
which damages by lightning are not made good, except to a limited
extent, by fire insurance companies, unless it is proved that the
edifices struck had been provided previously with efficient conductors.
These laws gave rise to a curious investigation some three or four
years ago. It was found that the principal fire insurance office--an
institution under the patronage of the Government, called the
‘Landesbrandkasse,’ or ‘County Fire Insurance Office’--had been called
upon a number of times to pay for damage caused by lightning in cases
where the buildings were provided with lightning conductors of the best
kind, in apparently perfect condition. Though the cases were very few
indeed--namely, but four out of 552 claims for damages from lightning
which had been made in the course of eight years--still, the interest
taken in the subject was so great, that the managers of the institution
appointed a special commissioner to inquire thoroughly into the
matter as to how it could happen that buildings provided with proper
conductors could ever be struck by lightning. The gentleman chosen to
undertake this task was Dr. W. Holtz, of Greifswald, well known as
having given much time to the study of the phenomena of electricity,
as well as the construction of lightning conductors. Dr. Holtz in due
course made his report, which was afterwards published in a scientific
journal called ‘Nachrichten des Naturwissenschaftlichen Vereins für
Neuvorpommern und Rügen,’ being the organ of a society under the latter
title. The report--which must be completely unknown in this country--is
full of interest, and well deserves being extracted from in several
notable particulars.

Dr. Holtz begins his report by referring to the well-known fact,
already dwelt upon, that in some instances lightning conductors have
got into disrepute because houses provided with them have been struck
and damaged. ‘Unhappily,’ he says, ‘there are still at the present
moment many persons who question the utility of conductors, simply
because it happens now and then, that lightning, apparently in entire
disregard of them, falls upon dwellings. These persons completely
overlook two facts, namely: first, that such cases are excessively
rare; and, secondly, what is far more important and more to the
point, that it is beyond dispute that whenever buildings nominally
provided with conductors are struck by lightning, these conductors are
not in an efficient state. Such buildings are absolutely in the same
condition as if they had no conductors at all.’ Dr. Holtz then goes on
to speak of his journey of inspection to inquire into the causes of
failure, or so-called failure, of lightning conductors. He says that,
having examined a vast number of conductors, he found that in a good
many instances real use had been sacrificed to ornament. He expresses
this somewhat quaintly, in scientific style, apparently with the
intention of not giving offence to anybody--not even to manufacturers
of lightning conductors. ‘It was found by me,’ Dr. Holtz states,
‘that the unreal was frequently placed above the real, and that many
lightning conductors, although very costly in the first instance,
afforded no certain protection.’ The meaning of this clearly is, that
too much attention is given to the upper part of conductors, especially
the pointed top--frequently covered with needless gilding--and far
too little to the part underground, forming the all-important earth
connection. It is a criticism true for other countries besides Germany.

Among the many interesting remarks of Dr. Holtz, evidently based on a
thorough knowledge of the subject which he treats, are some good ones
about the necessity of constructing lightning conductors, not slavishly
after old models, but in conformity with modern requirements, carefully
considering the nature of the buildings to be protected and their
materials. ‘The increase of metals,’ he says, ‘in the construction
of houses, both inside and outwardly, is assuming larger proportions
from year to year. An absolute consequence of it is, that the electric
force called lightning is tempted, far more than was the case in older
dwellings, not to go to the conductor at all, or, if attracted to
it, to leave the path afterwards, seeking other attractions. I found
this to have been the case, in the course of my investigations, in
several instances, two of them notable ones. The first was that of the
public school of the town of Elmshorm, struck by lightning away from
the conductor; and the second that of the church of St. Lawrence, in
the town of Itzehoe, where the conductor was struck at first, but the
lightning deviated subsequently from its metal path. In both cases I
found that the non-efficacy of the conductor was caused by a number of
gas-pipes. But there are many other metallic masses besides gas-pipes
which interfere thus with the proper action of lightning conductors.
More or less, all metals do so, especially those which lead to the
ground, or are in contact with moisture. Water-pipes will attract
the electric force even more than gas-pipes, and likewise the metal
tubes which carry the rain from the roof into the ground. But it may
also happen that mere ornaments on the roof, more particularly if of
thick metal, and carried all along the top and sides, may divert the
electric force from the conductor, although they have no connection
whatever with the ground. Even the many wires outside and inside
houses, for bells and other purposes, may do mischief. There can be
no doubt whatever that the large increase of the use of metals in the
construction and ornamentation of modern houses has led to far greater
danger to which they are exposed from lightning. At the same time
there is equally little doubt that all this increased danger may be
absolutely guarded against by the setting up of lightning conductors
by competent persons, carefully designed to meet all cases.’ Dr. Holtz
adds, further on, that one most important element of protection to
be obtained from conductors consists in the regular testing of them,
without which, indeed, there can be no permanent security.

What the writer says on the inspection of conductors is particularly
worth quoting. ‘A lightning conductor,’ he remarks, ‘however excellent
in the first instance, may lose all its good qualities, for several
reasons. In the first instance it may suffer, like all mundane things,
from age. The decrepitude will come on all the sooner whenever the
materials are not of the best kind, or whenever little care has been
taken in properly connecting the various parts. This is frequently
the case in conductors of old design. But, even if all has been done
that scientific skill can accomplish, age will make itself felt some
time or other. Oxidation will play its part; so will the warfare of
the elements. However safely secured at first, the attachment of the
parts to the buildings will get loose, or perhaps even broken. Repairs
consequently become indispensable. When are they to be effected? It
can only be indicated by testing the conductor from time to time.’
Dr. Holtz next dwells at some length on the necessity of conductors
being designed by thoroughly competent persons; not mere ‘lightning
rod men,’ who are able to take into account all the particulars of the
building which is to be protected, more especially the metal employed
in the construction. ‘A conductor,’ he truly remarks, ‘cannot be
expected to be a trustworthy protection against the destructive force
of lightning, if simply set up over a house without consideration of
its outer and inner features. Perhaps in buildings of olden times, into
the construction of which metals seldom or never entered, a simple
wire running from top to bottom, surmounted by an iron rod, was quite
sufficient, but this is no longer the case, all the circumstances
having been completely altered. The wire, however thin, was not merely
the best, but the only path for the electric force. But at present
the masses of metal used in the construction of buildings constitute
a number of rival paths, and it requires very careful consideration
indeed to lay down an absolutely infallible lightning conductor in such
a way as to overcome all influences opposing its action. Therefore
conductors of old construction can not only not be expected to be
efficacious under modern exigencies, but even those made at the present
time cannot be expected to be efficient under circumstances which,
probably, the future may bring forth. There is really nothing else to
make a lightning conductor a safe protection under all circumstances,
and at all times, but regular, constant, and skilful examination.’

To the three great causes before indicated which make the regular
testing of conductors an almost imperative necessity, several minor
ones may be added. Among them may be cited the frequency of repairs
of the walls and roofs of houses. Our modern houses, as we all know,
are not built, like those of the Romans, ‘for an eternity,’ but in the
vast majority, particularly in towns, are ‘leaseholds for ninety-nine
years.’ Many of them, perhaps, can scarcely be expected to last
ninety-nine years, being constructed by their builders on the principle
of Peter Pindar’s razors, ‘not to shave, but to sell.’ Hence the
absolute necessity of repairs without end. Without casting the least
slur upon the character of the artisans who execute these, bricklayers,
plasterers, painters, plumbers, and others, it may be fairly asserted
that they are densely ignorant as to the nature of lightning
conductors. It is not at all a wonder that this should be so, since
they share their ignorance with many persons of far higher education,
who know no more of the action of the electric force in seeking its
way from the clouds into moist earth than they do of that of a voltaic
apparatus, or of a condensing steam-engine. These artisans, then, in
whose hands the repairs of houses are left, naturally treat the narrow
strip of metal running from the top of houses to the bottom with great
indifference, not having the slightest idea of its being one of the
most marvellous conceptions of the human mind. It has been reported,
on good authority, that there are frequently workmen to be found, such
as house painters and others, whose business it is to ‘decorate’ the
outside of dwellings with the stuff called ‘stucco,’ who feel a sort
of mild hatred for lightning conductors, as interfering with their
achievements, and, as they think, disfiguring the beauties which they
are creating. Woe to the poor conductor within their reach! Unless very
conspicuously placed, which is rarely the case, the tenant of a house
will seldom discover in time that the slender rope, or ribbon, which
gives him and his family protection against lightning has been broken
by cunning hands when the last repairs were effected, and the ends
stowed away in the gutter on the roof. The discovery will be made, in
the absence of inspection, probably, only under the fierce light of a
flash of lightning from a passing thunderstorm.

If in towns the ever increasing accumulation of gas, of water, and of
drainage pipes constitutes a danger against the efficacy of lightning
conductors--to be guarded against only by frequent testing--there is
another source of danger arising in the country. It is in the planting
of new trees and the growth of old ones which is constantly going on
in the vicinity of the thousands of country houses and mansions with
which Great Britain is dotted from one end to the other, more than
any other country in the world. The fact has already been dwelt upon,
that trees are more liable to be struck by lightning than any other
natural objects, the reason of it being unknown, except in the very
probable surmise that the moisture in them forms the natural cause why
the electric force seeks its path through them to the earth. Whatever
the cause or causes, there can be no doubt that trees are incessantly
struck by lightning, and that they are the more exposed to be struck
the higher they are and the wider the extent of their branches.
Consequently, wherever trees are being planted, or growing up around
houses, the greatest care should be taken in designing lightning
conductors, so as to provide against the action exercised by them in
juxtaposition to the electric force. Thus, if trees, originally small,
should reach to such a height above dwellings as to make it possible
that a stroke of lightning will fall upon them, in preference to the
conductor, the arrangements for protection will have to be altered,
so as to ensure the safety of the house nearest these particular
trees. Again, if, as often happens, there are new trees planted near
a building the side of which has no protection whatever, such as a
greenhouse or conservatory, the conductor should be extended in this
direction. In connection with trees, mention must be made of wells
and fountains, as possible dangers to the proper action of lightning
conductors. Many a disaster has been caused by newly-made wells to
dwellings which were previously well protected by conductors. The
only safeguard against danger arising from these and numerous other
causes, which it would be tedious to specify, lies in careful, constant
inspection and testing of conductors.

It is lamentable to think that while the regular inspection of
lightning conductors has been admitted long ago to be a necessity in
many countries on the Continent of Europe, we as yet have taken no
steps whatever to realise it. There is, probably, not a single public
building in England which has conductors systematically tested from
time to time. While there are tens of thousands of edifices, private
and public, that are entirely without protection against lightning,
there are many thousands of others which, nominally protected, are
in reality in the same position. They have conductors, but it is
impossible to say whether they would be efficacious were a more than
usually heavy stroke of lightning to fall upon them. The inmates of
such dwellings live in fancied security, which is the more to be
deplored, as it would be so easy to make it real. All that is required
is a knowledge of the subject. With the growth of such knowledge it is
certain that the inspection of conductors will become general, with
the good effect, above all others, of setting at rest all doubts as
to the infallible security they afford, if properly constructed and
maintained, against damage from lightning.




APPENDIX.

_BIBLIOGRAPHY OF WORKS BEARING UPON LIGHTNING CONDUCTORS._


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           DR. WALLIS. On the Effects of Thunder and Lightning. Phil.
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  1747.    MAFFEI. Della Formazione dei Fulmini. 4to. Verona.

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  1748.    WM. WATSON. Of the Experiments made by some Gentlemen
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           BARBERET. Discours, qui a remporté le Prix de Physique, au
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           H. EELES. On the Cause of Thunder. Phil. Trans. xlvii. 524.

           A. G. KÄSTNER. Nachricht von einem besonderen Lichte. Hamb.
              Magaz. ix. 359.

           J. G. KRULL. Versuche zur Bestätigung der Meinung, dass die
              elektrische Materie mit der Materie des Donners und
              Blitzes eine grosse Aehnlichkeit habe. Hannover:
              Gelehrte Anzeigen vom J. 1752.

           LE MONNIER. Observations sur l’Electricité de l’Air. Mém.
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           CH. MYLIUS. Extract of a Letter from Mr. Mylius, of Berlin,
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           ABBÉ NOLLET. Extracts of two Letters of the Abbé Nollet to
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           W. WATSON. Concerning the Electrical Experiments in
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  1753.    P. A. BINA. Elektr. Versuche, Gewitter und Regen
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           J. BUNSEN. Versuch, wie die Meteora des Donners und
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           Aufsteigens der Dünste, incl. des Nordscheins, aus elektr.
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           G. BECCARIA. Dell’ Elettricismo artifiziale e naturale.
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           W. WATSON. On Nollet’s Electricity. Phil. Trans. xlviii.
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           M. MAZEAS. Electricity of the Air. Phil. Trans. xlviii.
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           M. LOMONOSOW. Oratio de Meteoris vi electrica ortis,
              habita 1753 4to. Petrop.

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              London, with his Answers to several Queries sent to
              him, concerning his Experiment in Electricity with a
              Kite. Phil. Trans. xlviii. 757.

           B. FRANKLIN. New Experiments and Observations. London.

  1755.    T. MARINI de Electricitate cœlesti, sive, ut alii
              vocant, naturali, Dissertatio. Commentar. de Bononiensi
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           DE ROMAS. Mémoires, où après avoir donné un moyen aisé
              pour élever fort haut, et à peu de frais, un corps
              électrisable isolé, on rapporte des Observations
              frappantes, qui prouvent, que plus le corps isolé
              est élevé au-dessus de la terre, plus le feu de
              l’Electricité est abondant. Mém. de Math. et de Phys.
              prés. à l’Acad. à Paris, p. 393.

           LE ROI. Mémoire sur l’Electricité résineuse, où l’on
              montre qu’elle est réellement distincte de
              l’Electricité vitrée, comme feu Mr. du Fay l’avoit
              avancé, et quelle nous fournit de nouvelles lumières
              sur les causes de l’Electricité naturelle et du
              Tonnerre. Mém. de Paris pour 1755, p. 264. Paris.

           J. VERATTI. Dissert. de Electricitate cœlesti. Comm. de
              Bononiensi Scientiar. et Artium Instituto atque Acad.
              p. 200. Bologna.

           J. VERATTI. Nachricht von einem elektrischen Versuche mit
              dem Gewitter. Hamburger Magazin, xv. 602.

  1756.    E. M. FAIT. Beobachtungen vom Donner und der
              Elektricität. Aus d. Engl, in Edinb. neuen Versuche und
              Bemerk. aus der Arzneykunst und übrigen Gelehrs. i.
              217. Altenburg.

           DE ROMAS. Electrical Experiments made with a Paper Kite
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  1757.    M. BUTSCHANY. Dissert. de Fulgure et Tonitru ex
              phænomenis electris. 4to. Gotting.

           TH. MARINI. Abhandlung von der himmlischen, oder wie Andere
              sie  nennen, natürlichen Elektricität. Allgem. Magaz.
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  1802.    J. A. EITELWEIN. Kurze Anleitung, auf welche Art
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           GEORG CHRISTOPH LICHTENBERG. Ueber Gewitterfurcht und
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  1803.    G. CH. LICHTENBERG. Neueste Geschichte der
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           J. F. LUTZ. Lehrbuch der theoretischen und practischen
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  1809.    J. J. HEMMER. Der Rathgeber, wie man sich vor Gewittern
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  1815.    — — — Ueber Blitzableiter aus Messingdraht. Anzeiger
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           BODDE. Ueber Blitzableiter. Gilbert’s Ann. li. 80.

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  1818.    C. A. W. WENZEL. Ueber Blitzableiter. Aus d. Französ.
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  1821.    LA POSTOLLE. Ueber Blitz- und Hagelableiter aus
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  1824.    J. C. V. YELIN. Dasselbe. Auch unter dem Titel: Ueber
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           ZIEGLER. Blitzableiter von Platina. Allgem. Handlungszeit. v.
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  1825.    FISCHER. Ueber die Nachtheile magnetischer eiserner
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  1827.    HEHL. Anleitung zur Errichtung und Untersuchung
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  1828.    MURRAY. Treatise on Atmospheric Electricity, including
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           R. HARE. Ueber die Ursachen, warum Wetterableiter in
              einigen Fällen nicht schützen, und die Mittel,
              dieselben vollkommen schützend zu machen, nebst einer
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  1830.    D. BREITINGER. Instruction über Blitzableiter im Canton
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           BÖCKMANN. Ueber Blitzableiter. Eine Abhandl. auf höchsten Befehl
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           POPPE. Gewitterbuchlein zum Schutz und zur Sicherstellung
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           PREIBSCH. Ueber Blitzableiter, deren Nutzbarkeit und Anlegung.
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           HARRIS. On the Utility of fixing Lightning Conductors on Ships.
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  1831.    MURRAY. Treatise on Atmospheric Electricity &c.,
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  1833.    A. DE TAVERNIER. Blitzableiter, genannt Antijupiter,
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           G. MAYR’S Abhandlung über Elektricität und sichernde
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  1834.    P. BIGOT. Anweisung zur Anlegung, Construction und
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  1835.    PLIENINGER. Ueber die Blitzableiter. 8vo. Stuttgart und
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  1837.    MARTYN ROBERTS. On Lightning Conductors, particularly
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           K. W. DEMPP. Ueber Blitzableiter. Förster’s Bauzeitung.
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  1838.    ARAGO. Sur le Tonnere. Annuaire du Bureau des Longit.
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           W. SNOW HARRIS. On the Protection of Ships from Lightning.
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           MR. STURGEON. On the Principle and Action of Lightning
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           J. MURRAY. Lightning Rods. Ib. iii. 64.

  1839.    WM. STURGEON. On Marine Lightning Conductors. Addressed
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           WM. STURGEON. Supplementary Note on Marine Lightning
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           W. SNOW HARRIS. On Lightning Conductors, &c., being an
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  1840.    Report of the Committee appointed by the Admiralty to
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  1841.    M. FARADAY. On some supposed Forms of Lightning. Phil.
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           W. STURGEON. A Paper on the Principle and Action of
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           W. L. WHARTON. The Effect of a Lightning Stroke. Ib. p. 162.

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  1842.    C. V. WALKER. On Lightning Conductors. Phil. Mag. xxi.
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           W. S. HARRIS. Observations on a Paper by C. V. Walker,
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           W. STURGEON. Description of a Thunderstorm as observed at
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           CHANTRELL. Ueber Blitzableiter. Polyt. Journ. lxxxvi. 179.

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           K. W. DEMPP. Vollständiger Unterricht in der Technik der
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  1843.    C. V. WALKER. Memoir on Lightning Flashes. Phil. Mag.
              xxii. (3 s.), 490.

           W. B. O’SHAUGHNESSY. On the use of Lightning Conductors in
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           Edinburgh Review. On the best Method of Protecting Buildings
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           MR. WALKER. On the Lightning Conductor on Royal Exchange.
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  1845.    MR. WHITE. On Protection of Buildings from Lightning.
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           CORNAY. Sur quelques Effets de l’Ouragan du 19 août observés
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           HENRY. Method of Protecting from Lightning Buildings covered
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  1846.    F. REICH. Electrische Versuche I. Abh. b. Begründ, der
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           STRICKER. Ueber Anwendung des Galvanismus zur Prüfung der
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  1847.    OLMSTED. A New Effect of the Magnetic Telegraph. Mech.
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           H. POSELGER. Berichte über atmosphärische Elektricität aus
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           R. BIRT. On the Production of Lightning by Rain. Phil.
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  1851.    M. QUETELET. On Atmospheric Electricity. Ib. i. (s. 4),
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           ARNOLD. Blitzableiter zum Schutz der Wärterbuden. Polyt.
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  1852.    H. POSELGER und G. KARSTEN. Berichte über
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           R. PHILLIPS. On the Electrical Condition of the
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  1853.    J. SPRATT’S. Fangstange für Blitzableiter. Polytechn.
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           LECLERQ. Sur la Cause qui produit le Bruit prolongé du Tonnerre.
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  1857.    BABINET. Ib. Compt. Rend. xliv. 636.

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  1858.    M. RONNEAU. Paratonnerres. De leur emploi pour mettre
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           M. POUILLET. Rapport fait à l’Académie sur la question de
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           M. PIMENTA. Sur un Nouveau Système de Paratonnerre. Compt.
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  1859.    G. A. ROWELL. An Essay on the Cause of Rain and its
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           C. TOMLINSON. The Thunderstorm. 8vo. London.

  1861.    DURET. Lettre sur un cas d’inefficacité des
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           GUIOT. Sur les Indications à remplir dans l’installation des
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  1862.    POUILLET. Rapport sur le Coup de Foudre qui a frappé le
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           C. TOMLINSON. On Lightning Figures. British Association
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           SACRÉ. Sur la Construction des Paratonnerres. Compt. Rend. lv.
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           CALLAUD. Lettre sur Certaines Dispositions qu’il donne aux
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           PERROT. Note sur les Résultats d’Experience entreprises dans le
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           PERROT. Note sur les Moyens d’augmenter l’Efficacité des
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  1863.    PERROT. Nouvelles Expériences tendant à prouver que
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           PERROT. Note sur les Rapports des Distances auxquelles
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  1865.    MELSENS. Sur les Paratonnerres à Conducteurs multiples.
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  1866.    CARL KUHN. Handbuch der angewandten Elektricitätslehre.
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  1867.    DR. OTTO BUCHNER. Die Konstruktion und Anlegung der
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           L. FIGUIER. Les Merveilles de la Science. 4to. Paris.

           M. BALTARD. Consulte l’Académie des Sciences de France
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           M. PELTIER. On Lightning Conductors. Proc. Belgian Academy
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           POUILLET. Projet d’instructions sur les Paratonnerres, preparé
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  1868.    LIEUT JOHN HERSCHEL, R. E. On the Lightning Spectrum.
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           M. LEFUEL. Rapport concernant les Paratonnerres des
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  1869.    M. MELSENS. Notice sur le Coup de Foudre de la Gare
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           W. DE FOUVIELLE. Eclairs et Tonnerres. 8vo. Paris.

           M. POUILLET. Instruction sur les Paratonnerres du Louvre
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           M. DE PARVILLE. Note sur un Procédé de Contrôle de la
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           M. VAILLANT. Un travail relatif aux mesures qui out été
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           M. BECQUEREL. On the Return Stroke of Lightning.
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  1871.    HERMANN J. KLEIN. Das Gewitter, und die Mittel sich vor
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  1872.    DR. WILHELM STRICKER. Der Blitz und seine Wirkungen.
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           HENRY WILDE. On the influence of Gas and Water-Pipes in
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           J. P. JOULE. On the Spectrum of Lightning. ‘Nature,’ vi. 186.

           M. W. DE FONVIELLE. The Efficiency of Lightning Conductors.
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           SECCHI. Phenomena produced by Lightning. Telegraph. Journal,
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           PROF. C. V. ZENGER. On Symmetric Conductors and the
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           M. D. COLLADON. Effects of Lightning on Trees. Compt. Rend.
              19. Nov. 1872.

           W. H. PREECE. On Lightning and Lightning Conductors. Jour.
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           JAS. GRAVES. On Lightning Conductors. Ib. p. 413.

  1873.    W. DE FONVIELLE. Note sur un Projet de Paratonnerres à
              Condensateur. Compt. Rend. lxxvi. 384.

           W. DE FONVIELLE. Sur Différents Mouvements électriques
              observés sur le Paratonnerre interrompu de
              l’Observatoire de Greenwich. Ib. 1282.

           W. DE FONVIELLE. Sur les Causes multiples qui provoquent
              la chute de la Foudre. Ib. 1394.

           W. DE FONVIELLE. On the Advantages of keeping Records of
              Physical Phenomena connected with Thunderstorms. Brit.
              Assoc. Report, 55. 1873.

           JNO. M. MOTT. Lightning and Lightning Rods. Journal of the
              Franklin Institute. 8vo.

           E. GRENET. Construction de Paratonnerres. 8vo. Paris.

           PROFESSOR REYNOLDS. On the Electrical Properties of Clouds and
              the Phenomena of Thunderstorms. Jour. Soc. Tel. Eng.
              ii. 161.

           DD. BROOKS. Lightning and Lightning Rods. Journal of the
              Franklin Institute, lxvi. 4.

           J. PHIN. Plain Directions for the Construction of
              Lightning Rods. 8vo. New York.

  1874.    A. CALLAND. Traité des Paratonnerres--leur Utilité,
              leur Théorie, leur Construction. 8vo. Paris.

           F. GAY-LUSSAC et CLAUDE POUILLET. Introduction sur les
              Paratonnerres, adoptée par l’Académie des Sciences.
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           E. NOUEL. Orage du 26 Mai à Vendôme: projet de
              Paratonnerre simplifié. Compt. Rend. lxxix. 237.

           F. MICHEL. Une Note relative à la Forme à donner aux
              Conducteurs des Paratonnerres. Ib. 1481.

           M. MELSENS. Deuxième Note sur les Paratonnerres. Bulletin
              de l’Académie, Roy. de Belgique, xxxviii. 8.

           M. MELSENS. Troisième Note sur les Paratonnerres. Acad.
              Royale de Belgique, xxxviii. 9, 10.

  1875.    M. MELSENS. Quatrième Note sur les Paratonnerres.
              Bulletin de l’Académ. Roy. de Belgique, xxxix. 6.

           PRÉFET DE LA SEINE. Instruction adoptée par la Commission qui
              a été chargée d’étudier la meilleure disposition à
              donner aux Paratonnerres surmontant les Edifices
              municipaux et departementaux. Comp. Rend. lxxxi. 1118.

           E. SAINT-EDME. Sur la Construction des Paratonnerres. Ib.
              949.

           J. CHEMINEAU. Une Description et un Dessin de
              Perfectionnement apportés aux Paratonnerres. Ib. 1203.

           M. FIZEAU. Avis de la Commission des Paratonnerres sur une
              Disposition nouvelle proposée pour les Magasins à
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           LT. COLONEL STOTHERD, R.E. On Earth Connections of
              Lightning Conductors. Jour. Soc. Tel. Eng. iv. 262.

           J. CLERK MAXWELL. Lightning Conductors. Ib. 429.

           DR. ANTONIN DE BEAUFORT. Notice sur les Paratonnerres. 8vo.
              Chateauroux.

           J. F. SPRAGUE. Electricity: its Theory, Sources, and
              Applications. 8vo. London.

           DR. MANN. Lightning Conductors. Jour. Soc. of Arts. xxiii.
              528.

           R. F. MICHEL. On the Construction and Maintenance of
              Lightning Conductors. Tel. Jour. iii. 44, 63.

  1876.    R. F. MICHEL. Note sur la Méthode à employer pour
              l’Essai des Conditions de Conductibilité des
              Paratonnerres. Compt. Rend. lxxxii. 342.

           R. F. MICHEL. Sur les Inconvénients que présente l’Emploi
              d’un Câble en fils de cuivre comme Conducteur de
              Paratonnerre. Ib. 1332.

           E. SAINT-EDME. Construction of Lightning Protectors. Tel.
              Jour. iv. 40.

           EUSTACE BUTTON. Notes on a Thunder-Storm which passed over
              Clevedon March 15, 1876. Jour. Soc. Tel. Eng. v. 260.

           W. E. AYRTON and JNO. PERRY. On Lightning Conductors. Ib.
              412. Lightning Conductors in Paris. Nature, xiii. 357.

           R. J. MANN. On the Construction of Lightning Conductors.
              Proc. Meteorological Soc. 8vo. London.

           O. BUCHNER. Die Konstruction und Anlegung der
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           Electric Conductors and Tall Chimneys. Jour. Soc. Tel. Eng. v.
              531.

           J. CLERK MAXWELL. On the Protection of Buildings from
              Lightning. Brit. Assoc. Report, 1877, 43.

           R. S. NEWALL. Lightning Conductors; their use as Protectors
              of Buildings, and how to apply them. 8vo. London.

  1877.    R. WILSON. Boiler and Factory Chimneys; with a Chapter
              on Lightning Conductors. 8vo. London.

           H. W. SPANG. A Practical Treatise on Lightning Protection.
              8vo. Philadelphia.

           R. S. BROUGH. On a case of Lightning, with an Evaluation of
              the Potential and Quantity of the Discharge in absolute
              Measure. Philos. Mag. vol. iv. (5 s.), 105.

           DR. HELLMAN. On Thunderstorms in Central Europe. (Pogg.
              Ann.) ‘Nature,’ xv. 263.

           M. JARRIANT. Sur une Nouvelle Disposition des Tiges du
              Paratonnerre. Compt. Rend. lxxxiv. 217.

           R. S. NEWALL. Should a Lightning Conductor be insulated?
              Times, April 12.

           M. MELSENS. De l’Application du Rhé-electromètre aux
              Paratonnerres des Télégraphes. Bulletins de l’Académie
              Royale de Belgique. xliii. No. 5.

           M. MELSENS. Des Paratonnerres à pointes, à conducteurs et
              à raccordements terrestres multiples. 8vo. Bruxelles.

  1878.    M. MELSENS. Cinquième Note sur les Paratonnerres.
              Bulletins de l’Acad. Royale de Belgique, xlvi. No. 7.

           W. HOLTZ. Ueber die Theorie, die Anlage und die Prüfung
              der Blitzableiter. 8vo. Greifswald.

           E. CARTAILHAC. Superstitions about Thunderstorms. L’Age de
              Pierre dans les Souvenirs et Superstitions populaires.
              8vo. Paris.

           R. J. MANN. Further Remarks concerning the Lightning Rod.
              Jour. Soc. Arts, xxvi. 328.

           M. MASCARL. On Artificial Thunderstorms. Nature, xvii. 515.

           R. P. BROWN. Effects of a Thunderstorm on the Colon
              Lighthouse. Jour. Soc. Tel. Eng. vi. 330.

           PROF. C. V. ZENGER. On the Law and Origin of Thunderstorms,
              from the Bulletin International, Paris. Nature, xvii.
              362.

           RICHARD ANDERSON. On Lightning Conductors and Accidents by
              Lightning. The Electrician, vol. i. 215.

           DR. NIPPOLDT. Dimensions of Lightning Rods. Telegraphic
              Journal, vi. 78.

           J. B. JOULE. On a Remarkable Flash of Lightning. Nature,
              xviii. 260.

  1879.    S. A. R. On the Cause of Thunder. Nature, xx. 29.

           R. S. NEWALL. On the Importance of a Sufficient Earth Contact
              for Lightning Conductors. Times, May 30 and June 14.

           Curious Effects of Lightning. Electrician, vol. iii. 181.

           AYRTON and PERRY. On the Earth Connection of Lightning
              Conductors. Nature, xix. 475.

           G. W. CAMPHUIS. On the Effects of Lightning. Nature, xx. 96.

           R. S. NEWALL. On Lightning Conductors. Nature, xx. 145.

           CHARLES S. TOMES. On Lightning Conductors. Nature, xx. 145.




INDEX.


  A
                                                                    PAGE
  Accidents and fatalities from lightning                        169–197

  Admont, Styria, convent struck by lightning                         67

  Air-pump, the inventor of the                                        2

  Alatri, the Cathedral of, struck by lightning                      203
  ———— Father Secchi’s account thereof                               203

  Allamand (John Nicholas), his researches on electricity              4

  Amber or ‘Electron’ and its properties                               1

  America, lightning protection in                                   133
  ———— the tramping ‘Lightning-rodmen’ of                            133
  ———— account of the details of the American system                 134
  ———— utilisation of gutters and rain-pipes in                      134
  ———— the protection of chimneys and air-shafts in                  136
  ———— the method of constructing the earth-terminal in              136
  ———— the protection of mineral oil tanks                           138

  Antrasme, France, church twice struck by lightning at the same
            point                                                     65
  ———— Arago’s remarks thereof                                        66

  Arago on the observation of thunderstorms                           62
  ———— on the efficiency of lightning-conductors                      73
  ———— on whether lightning-conductors should be carried down
            inside or outside a building                             159

  Area of protection theory                            77, 101, 126, 145

  Auffangstange, the German                                          145

  Austria, statistics of fires caused by lightning in                174


  B

  Baden, statistics of deaths from lightning in                      173

  ‘Balls _v._ points,’ the controversy of                             40

  Banker’s iron safe struck by lightning                             221

  Bavaria, statistics of fires caused by lightning in                173

  Becquerel (Antoine C.), his experiments on the conductivity of
            metals                                                    51

  Bevis (Dr.), experiments in electricity                              7

  Bibliography of works bearing upon lightning-conductors            231

  Black Rock, Cork, St. Michael’s Church struck by lightning         184

  Brass wire, the use of, for lightning-conductors              105, 107

  Brescia, Italy, powder-magazine destroyed by lightning             200

  Brussels, the Hôtel de Ville. The system of lightning-conductors
            at                                                       111

  Buffon (Count de), his opinion of Franklin’s first pamphlet on
            electricity                                               19

  Buffon (Count de), his promotion of experiments in electricity      20

  Buttor (Eustace) account of the striking of Christ Church,
            Clevedon, by lightning                                   208


  C

  Carthusian monks at Paris, electrical experiments made on            6

  Cavendish (Lord Charles), experiments in electricity                 7

  Chains, iron, the use of, for lightning-conductors                 102

  Chimney-shafts, the protection of, from lightning                  163

  Chimneys and air-shafts, the protection of, from lightning in
            America                                                  136

  Churches struck by lightning       27, 38, 64, 65, 146, 147, 153, 176,
            177, 181, 182, 183, 184, _see also_  186–196, 201, 203, 208

  Churches, the protection of, from lightning                   152, 156

  Coiffier first draws lightning from the atmosphere                  21

  Cleopatra’s Needle, the protection of, from lightning              141

  Clevedon, Christ Church struck by lightning                        208
  ———— Eustace Buttor’s account thereof                              208

  Cockburn (Sir George) and Sir William Snow Harris                   89

  Collinson (Peter) Correspondence with Benjamin Franklin     12, 13, 17

  Compass reversed by a lightning-stroke                              56

  Compensator for contraction and expansion in lightning-conductors  128

  Copper, the relative value of different kinds of                   109
  ———— the necessity for its purity when used for
            lightning-conductors                                     109
  ———— and iron, the relative electrical conductivity of         52, 143
  ———— rope-conductors, the proper thickness and weight for
            different buildings                                      151
  ———— description of                                            62, 164

  Cromer, Norfolk, church damaged by lightning                       147

  Cuneus, his experiments in electricity                               4

  Cyprus, the copper of                                               52


  D

  Dalibard (M.), his experiments in electricity                       20

  Davy (Sir Humphrey), his experiments on the conductivity of metals  50

  Deaths from lightning, statistics of                           170–175

  De la Rive (Professor) on the origin of atmospheric electricity     71

  Dumdum, India, destruction of a magazine by lightning at            92


  E

  Earth connection, the French methods of arranging the              131
  ———— general description of                                    198–217
  ———— Benjamin Franklin on                                          199
  ———— Rev. Dr. Hemmer on                                            200
  ———— Professor Landriani on                                        201

  Electrical machines, Otto von Guericke’s                             2
  ———— Sir Isaac Newton’s                                              2

  ‘Electrical tubes,’ the mania for                                9, 10

  Electricity, the early history of                                    1
  ———— the discovery of the instantaneity of its movement              8
  ———— positive and negative, Benjamin Franklin on                    26

  ‘Electron’ or amber, and its properties                              1

  Electro-magnetism, Hans Oersted’s researches in                     57

  England and Wales, deaths from lightning in                        170

  England, lightning protection in                               140–168


  F

  Fatalities and accidents from lightning                        169–197

  Fires caused by lightning in Russia                                171

  Folkes (Martin), experiments in electricity                          7

  France, the ‘Instruction’ of the Paris Academy on
            lightning-conductors                                      75
  ———— the general adoption of lightning-conductors in                77
  ———— the protection of powder-magazines in, from lightning          82
  ———— lightning protection in                                       125
  ———— neglect of lightning-conductors in                            125
  ———— account of the details of the French system                   126
  ———— the ‘area of protection’ theory in                            126
  ———— the ‘ridge-circuit’ as used in                                129
  ———— deaths from lightning in                                      171

  Franklin (Benjamin), his early life                             10, 11
  ———— his first experiments in electricity                        12–19
  ———— correspondence thereon with Peter Collinson            12, 13, 17
  ———— on the identity of lightning and electricity                   16
  ———— ‘New Experiments and Observations in Electricity’              18
  ———— his ‘kite’ experiment                                          22
  ———— honours conferred on him                                       24
  ———— his first lightning-conductor                                  25
  ———— his experiments therewith                                      25
  ———— on positive and negative electricity                           26
  ———— his lightning-conductor on West’s house                        30
  ———— his letter to Professor Winthrop defending
            lightning-conductors                                      36
  ———— his troubles in making his first lightning-conductor          101
  ———— on the earth connection of lightning-conductors               199

  French technical terms for lightning-conductors                    102

  Fuller (Thomas) on fires caused by lightning                       176


  G

  Galvani’s experiments on animal electricity                         70

  Galvanometer, the invention of the                                  58
  ———— a new form of                                                  60

  Geneva, the progress of lightning-conductors in                     43

  Genoa, St. Mary’s Church struck by lightning                       201
  ———— Professor Landriani thereon                                   202

  ‘Gentleman’s Magazine’ _quoted_                                     40

  George III., his opinions on lightning-conductors               41, 42

  German technical terms for lightning-conductors                    102
  ———— theories on the earth connection                         212, 214

  Germany, the progress of lightning-conductors in                    43

  Gilbert (Dr. William), his electrical discoveries                    2

  Gratz, Austria, buildings struck by lightning at                    68

  Gray (Stephen), his researches on electricity                        3

  Guericke (Otto von) his electrical machine                           2


  H

  Harris (Sir William Snow) his efforts for the protection of ships
            from the effects of lightning                             85
  ———— and Sir George Cockburn                                        89
  ———— his system for protecting ships                                90
  ———— his ‘Instructions for powder-magazines’                        93
  ———— his system for the protection of Westminster Palace       98, 118

  Hauksbee (Francis), his researches on electricity                    2

  Height of lightning-clouds                                          67

  Hemmer (Rev. Dr.), his theories on the earth connection            200

  Henly’s system for protecting ships from lightning                  90

  ‘Heretical-rods’                                                    44

  Highbury Barn, electrical experiments made at                        8

  Holtz (Dr. W.), on the construction and maintenance of
            lightning-conductors                                     223

  Humboldt (Alex. von) on the height of lightning-clouds              67


  I

  India, the use of lightning-conductors in                           92

  Ingenhousz (Dr. Johan) and lightning-conductors                     47

  Inspection of lightning-conductors                             218–229

  ‘Instruction’ of the Paris Academy on lightning-conductors          75

  Insulators, the dangers of                               147, 160, 176

  Iron and Copper, the relative electrical conductivity of       52, 143
  ———— safe, a banker’s, struck by lightning                         221

  Italy, the progress of lightning-conductors in                      44


  J

  Jarriant’s system of lightning-protection                          133

  Josephus’ account of Solomon’s Temple                               63


  K

  Kant (Immanuel) on Benjamin Franklin                                24

  Kastner (Professor), his report on the partial destruction of
            Rosstall Church by lightning                             106

  Kew, lightning-conductor erected by George III. at                  41

  Kinnersley (Ebenezer), his lectures on lightning-conductors         27

  Kite, Benjamin Franklin’s experiment with                           22

  Kleist (Ewald George von) and the discovery of the Leyden Jar        5


  L

  Landriani (Professor), his theories of earth protection            201

  Laughton-en-le-Morthen, church damaged by lightning           153, 176
  ———— R. S. Newall’s comments thereon                          153, 154

  Lead, the use of, for lightning-conductors                         104

  Leicester, St. George’s Church struck by lightning                 177

  Lenz (Professor) his experiments on the conductivity of metals      52

  Leopold, Duke of Tuscany, and lightning-conductors                  44

  Le Roy (David) and the protection of the Louvre from lightning      80
  ———— (J. B.), his theory of protecting buildings from lightning    101

  Leyden Jar, the first discovery of the                               5

  Lightning, superstitions in regard to                               63

  Lightning-clouds, the height of                                     67

  Lightning-conductors, the discovery of                           17–24
  ———— early experiments with                                     25, 33
  ———— the clergy on                                                  26
  ———— Professor Winthrop’s defence of                            26, 27
  ———— E. Kinnersley’s lectures on                                    27
  ———— ‘Poor Richard’s Almanac’ on                                    28
  ———— the gradual spread of                                       34–48
  ———— Abbé Nollet’s animadversions on                            35, 37
  ———— Franklin’s reply thereto                                   36, 37
  ———— their general use in North America                             38
  ———— their first erection on St. Paul’s                             39
  ———— their progress in Germany                                      43
  ———— Italy                                                          44
  ———— the various metals used for                                    50
  ———— Arago on the efficiency of                                     73
  ———— the French ‘Instruction’ on                                    75
  ———— Professor Pouillet on                                          78
  ———— for ships                                                      85
  ———— Sir William Watson’s system of, for ships                      87
  ———— Sir William Snow Harris’s system of, for ships                 90
  ———— F. McTaggart’s opinion of                                      92
  ———— their use in India                                             92
  ———— the best material for                                     100–110
  ———— German and French technical terms for                         102
  ———— and weathercocks                                              121
  ———— Jarriant’s form of                                            133
  ———— the twofold function of                                       142
  ———— the insulation of                                   147, 160, 176
  ———— Newall’s system of                                        140–168
  ———— should they be carried down inside or outside the building    158
  ———— Professor Clerk Maxwell’s theory of                           164
  ———— the necessity for periodically inspecting                     218
  ———— Dr. W. Holtz on the construction and maintenance of           223

  ‘Lightning-rod men,’ the tramping, of America                      133

  Lightning and thunderstorms, character of                           62
  ———— protection, inquiries into                                  73–84

  Line of least resistance, the                                 142, 148

  Lisle (M. de) on the height of lightning-clouds                     67

  Louis XV. and experiments in electricity                         6, 19

  Louvre, the protection of the, from lightning                       80
  ———— the first public building in France fitted with
            lightning-conductors                                      80


  M

  McTaggart (F.), his opinion of lightning-conductors                 92

  Magnetisation of metals by lightning                                56

  Magnetism and lightning, the connection between                     56

  Majendie (Major), report on the destruction by lightning of the
            powder magazine, Victoria Colliery, Burntcliffe          147

  Marly-la-Ville, Dalibard’s electrical experiments at                20

  Matthiessen (Professor), his researches on the conductivity of
            copper                                                   109

  Maxwell (Professor Clerk, F.R.S.), his theory of lightning
            protection                                               164

  Melsens (Professor), his system of lightning-conductors at the
            Hotel de Ville, Brussels                                 111

  Merton College Chapel, Oxford, struck by lightning                 182

  Metals as conductors of electricity                              49–61

  Metals, the different conductivity of various                    50–55

  Michel (R. F.), his modified terminal-rod                          132

  Mineral oil-tanks, the protection of, from lightning in America    138

  Monks, Carthusian, electrical experiments made on                    6

  Musschenbroek (Peter Van), his researches on electricity          4, 5


  N

  Newall (R. S., F.R.S.), his copper-rope manufactory           110, 142
  ———— on the church at Laughton-en-le-Morthen being struck by
            lightning                                           153, 154

  Newall’s system of protecting buildings from lightning             140
  ———— copper-rope conductors                                   162, 164

  Newbury Church, Massachusetts, struck by lightning                  27

  New River, electrical experiments made on the                        8

  Newton (Sir Isaac), his electrical machine                           2

  Nollet (Abbé), his criticisms on Franklin’s electrical
            experiments                                           19, 35
  ———— his animadversions on lightning-conductors                 35, 37
  ———— Franklin’s reply thereto                                   36, 37


  O

  Oersted (Hans Christian) his researches in electro-magnetism    55, 57

  Ohm (Professor), his experiments on the conductivity of metals      53

  Ohm’s law                                                           59

  Oil, mineral, tanks, the protection of, from lightning in America  138

  Orsini family and lightning-conductors                              64

  Oxford, Merton College Chapel struck by lightning                  182


  P

  Padua, the first lightning-conductor in                             48

  Painting lightning-conductors                                      129

  Paratonnerres, the Paris Academy ‘Instruction’ on                   75

  Paris Academy, the ‘Instruction’ of the, on lightning-conductors    75

  Paris, death of two persons by the fall of a ‘tige’ from steeple
            of St. Gervais                                           146

  Peltier (Jean Athanase), his researches in electricity              71

  ‘Physico-mechanical experiments,’ Hauksbee’s                         3

  Pliny the Elder, on the observation of thunderstorms                62

  ‘Points _v._ balls,’ the controversy of                             40

  ‘Poor Richard’s Almanac’ and lightning-conductors                   28

  Pope, the, on electrical experiments on monks                        7

  Pouillet (Professor Claude), his experiment on the conductivity of
            metals                                                    54
  ———— on lightning-conductors                                        78

  Powder-magazines in France, the protection of, from lightning       82
  ———— Sir William Snow Harris’s instruction for protecting           93

  Pringle (Sir John) his resignation of the Presidency of the Royal
            Society in 1777                                           41

  Protestantism and lightning-conductors                              43

  Prussia, statistics of deaths from lightning in                    170

  Purfleet, building struck by lightning in 1777                      41


  R

  Rarefied air, the conductivity of                             142, 149

  Raven (Mr.), his house in Carolina, U.S., struck by lightning      159
  ———— Arago’s comments thereon                                      159

  Réaumur (Rene Antoine de) Musschenbroek’s letter to, on the Leyden
            Jar                                                        5

  ‘Return strokes’ of lightning                                       70

  Richmann (Professor G. W.), his experiments on electricity          31
  ———— his death thereby                                              32

  ‘Ridge Circuit’ as used in France                                  129

  Robespierre and lightning-conductors                            36, 43

  Roman Catholicism and lightning-conductors                      42, 44

  Rosenburg, Austria, church repeatedly struck by lightning at        64

  Rosstall, Bavaria, church struck by lightning at                   105
  ———— Professor Kastner’s report thereon                            106

  Royal Navy, vessels of the, destroyed by lightning                  88

  Royal Society and Benjamin Franklin                                 17

  Russia, statistics of deaths from lightning in                     171


  S

  St. Bride’s Church, London, struck by lightning in 1764             38
  ———— Dr. William Watson’s account thereof                           39
  ———— account of the damage done                                    183

  St. Omer, the first lightning-conductor at                          35

  St. Paul’s Cathedral, the erection of lightning-conductors upon  39–41

  Saussure (Professor Horace de) erects the first lightning-conductor
            in Geneva                                                 43
  ———— the opposition thereto and his manifesto thereon           43, 44
  ———— on the height of lightning-clouds                              67
  ———— on the origin of atmospheric electricity                       70

  Schleswig-Holstein, thunderstorms in                               222

  Secchi (Father) on the protection of churches from lightning       203

  Ships destroyed by lightning, statistics of                         88

  Shooter’s Hill, electrical experiments made at                       8

  Siena, the erection of lightning-conductors on the Cathedral at     45

  Smoke, the conductivity of                                         142

  Solokow and Professor Richmann’s experiment in electricity          32

  Solomon’s Temple, its immunity from lightning-strokes               63

  Staples for lightning-conductors                                   163

  Statistics of deaths, fires, and damage caused by lightning        170

  Superstitions in regard to lightning                                63

  Sweden, statistics of deaths from lightning in                     172

  Switzerland, statistics of deaths caused by lightning in           175


  T

  Terminal-rods, Newall’s                                            144

  Thomson (Sir William, F.R.S.), his researches on the conductivity
            of copper                                                109

  Thunderstorms and lightning, the character of                       62

  ‘Tightening-screw,’ the                                            162

  Tin, the use of, for lightning-conductors                          104

  Toaldo (Abbé Giuseppe) and lightning-conductors                     45

  ‘Tomlinson’s Thunderstorm,’ _quoted_                               177

  Torpedo fish and electric shocks                                     1

  Trees, their liability to be struck by lightning                   228

  Tuscany, the erection of lightning-conductors upon
            powder-magazines in                                       48


  U

  United States, lightning protection in                             133

  Units, the law of                                                   68


  V

  Vaccination and lightning-conductors, analogy between the progress
            of                                                        46

  Venice, the erection of lightning-conductors in                     48

  Victoria Colliery, Burntcliffe, destruction of the magazine by
            lightning                                                146
  ———— Major Majendie’s report thereon                               147

  Volta and the ‘return stroke’                                       70

  Voltaire, his _bon mot_ concerning lightning                       158


  W

  Wall (Dr.), on electricity and lightning                             3

  Watson (Dr. William), experiments in electricity                     7
  ———— the first to erect a lightning-conductor in England            38
  ———— on St. Bride’s Church being struck by lightning                39
  ———— and the protection of the Royal Navy from lightning            86

  Weathercocks and lightning-conductors                               21

  Weber (Dr.) and the law of units                                    59

  West-End Church, Southampton, struck by lightning                  181

  Westminster Bridge, electrical experiments made from                 7
  ———— Palace, the system of lightning-conductors at             98, 118

  Wilson, the advocate of ‘balls _versus_ points’                     40

  Winckler (Dr.), his experiments in electricity                    5, 6

  Windsor Castle inadequately provided with lightning-conductors     175

  Winthrop (Professor), his defence of lightning-conductors       26, 27
  ———— Franklin’s letter to, defending lightning-conductors           36

  Wurtemberg, statistics of deaths caused by lightning in            175


  Y

  Yelin (J. C. von) his advocacy of brass wire for
            lightning-conductors                                     105


_Spottiswoode & Co., Printers, New-Street Square, London._




Transcriber’s Notes


Punctuation, hyphenation, and spelling were made consistent when a
predominant preference was found in this book; otherwise they were not
changed.

Simple typographical errors were corrected; occasional unbalanced
quotation marks retained. The spelling of non-English words was not
checked or corrected.

Ambiguous hyphens at the ends of lines were retained.

In the original text, Figures and Footnotes were numbered from “1” in
each chapter. Here, they are numbered in a single sequence for the
entire eBook, and references to them have been adjusted accordingly.

Inconsistent font styles (normal, italics, small-caps) of the
abbreviation “Fig.” in illustration captions have regularized to the
predominant form, “normal” (no italics, no small-caps).

Index not checked for proper alphabetization or correct page references.

Page 184: No closing single quotation mark for text beginning
“‘completely indicated”.





End of Project Gutenberg's Lightning Conductors, by Richard Anderson

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