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Royal Institution of Great Britain.

EXTRA EVENING MEETING,

Monday, March 13, 1882.

H.R.H. THE PRINCE OF WALES, K.G. F.R.S. Vice-Patron and
Honorary Member, in the Chair.

EADWEARD MUYBRIDGE, of San Francisco.



_The Attitudes of Animals in Motion, illustrated with the
Zoopraxiscope._


The problem of animal mechanism has engaged the attention of mankind
during the entire period of the world's history.

Job describes the action of the horse; Homer, that of the ox; it engaged
the profound attention of Aristotle, and Borelli devoted a lifetime to
its attempted solution. In every age, and in every country, philosophers
have found it a subject of exhaustless research. Marey, the eminent
French savant of our own day, dissatisfied with the investigations of his
predecessors, and with the object of obtaining more accurate information
than their works afforded him, employed a system of flexible tubes,
connected at one end with elastic air-chambers, which were attached to
the shoes of a horse; and at the other end with some mechanism, held in
the hand of the animal's rider. The alternate compression and expansion
of the air in the chambers caused pencils to record upon a revolving
cylinder the successive or simultaneous action of each foot, as it
correspondingly rested upon or was raised from the ground. By this
original and ingenious method, much interesting and valuable information
was obtained, and new light thrown upon movements until then but
imperfectly understood.

While the philosopher was exhausting his endeavours to expound the laws
that control, and the elements that effect the movements associated with
animal life, the artist, with a few exceptions, seems to have been
content with the observations of his earliest predecessors in design, and
to have accepted as authentic without further inquiry, the pictorial and
sculptural representations of moving animals bequeathed from the remote
ages of tradition.

When the body of an animal is being carried forward with uniform motion,
the limbs in their relations to it have alternately a progressive and a
retrogressive action, their various portions accelerating in comparative
speed and repose as they extend downwards to the feet, which are
subjected to successive changes from a condition of absolute rest, to a
varying increased velocity in comparison with that of the body.

The action of no single limb can be availed of for artistic purposes
without a knowledge of the synchronous action of the other limbs; and to
the extreme difficulty, almost impossibility, of the mind being capable
of appreciating the simultaneous motion of the four limbs of an animal,
even in the slower movements, may be attributed the innumerable errors
into which investigators by observation have been betrayed. When these
synchronous movements and the successive attitudes they occasion are
understood, we at once see the simplicity of animal locomotion, in all
its various types and alternations. The walk of a quadruped being its
slowest progressive movement would seem to be a very simple action, easy
of observation and presenting but little difficulty for analysis, yet it
has occasioned interminable controversies among the closest and most
experienced observers.

When, during a gallop, the fore and hind legs are severally and
consecutively thrust forwards and backwards to their fullest extent,
their comparative inaction may create in the mind of the careless
observer an impression of indistinct outlines; these successive
appearances were probably combined by the earliest sculptors and
painters, and with grotesque exaggeration adopted as the solitary
position to illustrate great speed. Or, as is very likely, excessive
projection of limb was intended to symbolise speed, just as excess in
size was an indication of rank. This opinion is to some extent
corroborated by the productions of the Grecian artists in their best
period, when their heroes are represented of the same size as other men,
and their horses in attitudes more nearly resembling those possible for
them to assume. The remarkable conventional attitude of the Egyptians,
however, has, with few modifications, been used by artists of nearly
every age to represent the action of galloping, and prevails without
recognised correction in all civilised countries at the present day.

The ambition and perhaps also the province of art in its most exalted
sense, is to be a delineator of impressions, a creator of effects, rather
than a recorder of facts. Whether in the illustrations of the attitudes
of animals in motion the artist is justified in sacrificing truth, for an
impression so vague as to be dispelled by the first studied observation,
is a question perhaps as much a subject of controversy now as it was in
the time of Lysippus, who ridiculed other sculptors for making men as
they existed in nature; boasting that he himself made them as they ought
to be.

A few eminent artists, notable among whom is Meissonier, have endeavoured
in depicting the slower movements of animals to invoke the aid of truth
instead of imagination to direct their pencil, but with little
encouragement from their critics; until recently, however, artists and
critics alike have necessarily had to depend upon their observation alone
to justify their conceptions or to support their theories.

Photography, at first regarded as a curiosity of science, was soon
recognised as a most important factor in the search for truth, and its
more popular use is now entirely subordinated by its value to the
astronomer, the anatomist, the pathologist, and other investigators of
the complex problems of nature. The artist, however, still hesitates to
avail himself of the resources of what may be at least acknowledged as a
handmaiden of art, if not admitted to its most exalted ranks.

Having devoted much attention in California to experiments in
instantaneous photography, I, in 1872, at the suggestion of the editor of
a San Francisco newspaper, obtained a few photographic impressions of a
horse during a fast trot.

At this time much controversy prevailed among experienced horsemen as to
whether all the feet of a horse while trotting were entirely clear of the
ground at the same instant of time. A few experiments made in that year
proved a fact which should have been self-evident.

Being much interested with the experiments of Professor Marey, in 1877 I
invented a method for the employment of a number of photographic cameras,
arranged in a line parallel to a track over which the animal would be
caused to move, with the object of obtaining, at regulated intervals of
time or distance, several consecutive impressions of him during a single
complete stride as he passed along in front of the cameras, and so of
more completely investigating the successive attitudes of animals while
in motion than could be accomplished by the system of M. Marey.

I explained the plan of my intended experiments to a wealthy resident of
San Francisco--Mr. Stanford--who liberally agreed to place the resources
of his stock-breeding farm at my disposal, and to reimburse the expenses
of my investigations, upon condition of my supplying him, for his private
use, with a few copies of the contemplated results. The apparatus used
and its arrangement will be better understood by a reference to the
accompanying drawings.

[Illustration: FIG. 1.]

[Illustration: FIG. 2.]

[Illustration: FIG. 3.]

[Illustration: FIG. 4.]

Fig. 1. A photographing lens, and camera containing a sensitised plate;
and side view of electro-exposor placed in front of camera.

Fig. 2. Back view of electro-exposor. Two shutters P P, each comprising
two panels, with an opening O between them, are adjusted to move freely
up and down in a frame; they are here arranged ready for an exposure, and
are held in position by a latch L and trigger T, all light being excluded
from the lens. A slight extra tension of the thread B, Fig. 4, will cause
a contact of the metal springs M S, and complete a circuit of electricity
through the wires W W and the electro-magnet M; the consequent attraction
causes the armature A to strike the trigger, the latch is released, the
shutters are drawn respectively upwards and downwards by means of the
rubber springs S S, and light is admitted to the sensitised plate while
the openings in the shutters are passing each other in front of the lens.

Fig. 3. Front view of electro-exposor after exposure of the plate.

[Illustration: FIG. 5.]

Fig. 5. General view of studio, operating track, and background. In the
studio are arranged 24 photographing cameras; at a distance of 12 inches
from the centre of each lens an electro-exposor is securely fixed in
front of each camera. Threads 12 inches apart are stretched across the
track (only two of which are introduced in the engraving), at a suitable
height to strike the breast of the animal experimented with, one end of
the thread being fastened to the background, the other to the spring,
Fig. 4, which is drawn almost to the point of contact.

The animal in its progress over the track will strike these threads in
succession, and as each pair of springs is brought into contact, the
current of electricity thereby created effects a photographic exposure,
as described by Figs. 2 and 4; and each consecutive exposure records the
position of the animal at the instant the thread is struck and broken.

For obtaining successive exposures of horses driven in vehicles, one of
the wheels is steered in a channel over wires slightly elevated from the
ground; the depression of each wire completes an electric circuit, and
effects the exposures in the same manner as the threads.

[Illustration: FIG. 6.]

Fig. 6. Operating track, covered with corrugated indiarubber, and marked
with transverse lines 12 inches apart. Each line is numbered, for the
purpose of more readily ascertaining the length of the animal's stride.
On one side of the track, and opposite to the battery of cameras, a white
background is erected at a suitable angle.

The camera in which any one negative in a series of exposures is made is
designated on that negative by the parallel direction of the vertical
stake with the horizontal line extending to the corresponding number
immediately opposite. The discriminating number of each series is marked
on each negative by the large numbers--229, for example--which are
changed for each movement illustrated.

For recording the successive attitudes of animals not under control, an
apparatus is used, comprising a cylinder, around which are spirally
arranged a number of pins; upon the cylinder being set in motion through
gearing connected with a spring or weight, these pins are consecutively
brought into contact with a corresponding number of metal springs; a
succession of electric currents are thereby created which act through
their respective magnets attached to the electro-exposors at regulated
intervals of time. The cylinder is put in motion either by bringing it
into gearing with other parts of the apparatus already in motion; or by
releasing a break with the hand, or by the action of some object at a
distance by means of an electric current.

This apparatus is principally used for illustrating the flight of birds,
the motions of small animals, and changes of position without continuous
progressive motion, such as occur during wrestling or turning a
summersault; when the cameras are directed towards the place where the
movements are being executed.

The boxes outside the studio (Fig. 5) contain cameras and
electro-exposors for obtaining synchronous exposures of a moving object
from different points of view.

The following analyses of some of the movements investigated by the aid
of electro-photographic exposures, are repeated by permission of the
President and Council from a paper read by the author before the Royal
Society, and are rendered more perfectly intelligible by the
reproductions of the actual motions projected on a screen through the
zoopraxiscope.


_The Walk._

Selecting the horse for the purposes of illustration, we find that during
his slowest progressive movement--the walk--he has always two, and, for a
varying period, three feet on the ground at once. With a fast walking
horse the time of support upon three feet is exceedingly brief; while
during a very slow walk all four feet are occasionally on the ground at
the same instant.

The successive order of what may be termed foot fallings are these.
Commencing with the landing of the left hind foot, the next to strike the
ground will be the left fore foot, followed in order by the right hind,
and right fore foot. So far as the camera has revealed, these successive
foot fallings during the walk are invariable, and are probably common to
all quadrupeds. But the time during which each foot, in its relation to
the other feet, remains on the ground, varies greatly with different
species of animals, and even with the same animal under different
conditions. During an ordinary walk, at the instant preceding the
striking of the left hind foot, the body is supported on the right
laterals, and the left fore foot is in act of passing to the front of the
right fore foot. The two hind feet and the right fore foot immediately
divide the weight. The right hind foot is now raised, and the left hind
with its diagonal fore foot sustains the body; the left fore next touches
the ground and for an instant the animal is again on three feet; the
right fore foot is immediately raised and again the support is derived
from laterals--the left instead of as before the right. One half of the
stride is now completed, and a similar series of alternations,
substituting the right feet for the left, completes the other half. These
movements will perhaps be more readily understood by a reference to the
longitudinal elevation, Fig. 7, No. 1, which illustrates some approximate
relative positions of the feet of a rapid walking horse, with a stride of
5 feet 9 inches. The positions of the feet indicated in this, and also in
the other strides illustrated in Fig. 7 are copied from photographs, and
from them we learn that during an ordinary walk the consecutive
supporting feet are:

  1. The left hind and left fore--_laterals_.
  2. Both hind, and left fore.
  3. Right hind and left fore--_diagonals_.
  4. Right hind and both fore.
  5. Right hind and right fore--_laterals_.
  6. Both hind, and right fore.
  7. Left hind and right fore--_diagonals_.
  8. Left hind and both fore.

[Illustration: LONGITUDINAL ELEVATION OF SOME CONSECUTIVE POSITIONS OF
THE FEET OF HORSES DURING VARIOUS MOVEMENTS.

Each line illustrates a single complete stride. The comparative distances
of the feet from each other, or from the ground, are approximate; not to
scale. Direction of movement -->

    _KEY._
                      _Rt._    _Left._
  _Hind Feet_
  _Fore Feet_
  _Line of ground_

               Length of
    Action.     Stride.   1   2   3   4   5   6   1D  2D  3D  4D  5D  6D

                ft.  in.
  1. Walking      5   9
  2. Trotting     7   6
  3.     "       17   6
  4.     "       18   3
  5. Ambling     10   3
  6. Racking     12   6

                          1   2   3   4   5   6   7   8   9   10  11  12
  7. Cantering   10   3
  8. Galloping   11   9
  9.     "       19   9
  10. Galloping, a conjectural stride  }
                   of 22 feet or more  }
]

Commencing again with the first position; it is thus seen that when a
horse during a walk is on two feet, and the other two feet are suspended
between the supporting legs, the suspended feet are laterals. On the
other hand, when the suspended feet are severally in advance of and
behind the supporting legs, they are diagonals.

These invariable rules seem to be neglected or entirely ignored by many
of the most eminent animal painters of modern times.


_The Trot._

By some observers the perfect trot is described as an absolutely
synchronous movement of the diagonal feet. This simultaneous action may
be considered desirable, but it probably never occurs.

Sometimes the fore foot will be raised before the diagonal hind foot,
sometimes afterwards; but in either instance, the foot raised first will
strike the ground first; repeated experiments with many racing and other
trotting horses confirmed this want of simultaneity. Selecting for an
example of the trot a horse making a stride of 18 feet in length, we find
that at the instant his right fore foot strikes the ground, the left hind
foot is a few inches behind the point where it will presently strike at
about 38 or 40 inches to the rear of the fore foot. When both feet have
reached the ground, the right hind leg is stretched back almost to its
fullest extent, with the pastern nearly horizontal, while the left fore
leg is flexed under the body. As the legs approach a vertical position
the pasterns are gradually lowered, and act as springs to break the force
of the concussion until they are bent nearly at right angles with the
legs.

At this period the left fore foot is raised to its greatest height, and
will frequently strike the elbow, while the right hind foot is but little
raised from the ground and is about to pass to the front of the left
hind.

The pasterns gradually rise as the legs decline backwards until the right
fore foot has left the ground and the last propelling force is being
exercised by the left hind foot; which accomplished, the animal is in mid
air.

The right hind foot continues its onward motion until it is sometimes
much in advance of its lateral fore foot, the former, however, being
gradually lowered, while the latter is being raised. The right hind and
both fore legs are now much flexed, while the left hind is stretched
backwards to its greatest extent with the bottom of the foot turned
upwards, the left fore leg is being thrust forwards and gradually
straightened, with the toe raised as the foot approaches the ground;
which accomplished, with a substitution of the left limbs for the right
we find them in the same relative positions as when we commenced our
examination, and one half of the stride is completed.

With slight and immaterial differences, such as might be caused by
irregularities of the ground, these movements are repeated by the other
pair of diagonals, and the entire stride is then complete.

Line 4 illustrates a stride of 18 feet 3 inches, and the order of
supporting feet are:--

  1. The right fore foot.
  2. The left hind and right fore feet.
  3. The left hind foot.
  4. Without support.
  5. The left fore foot.
  6. The right hind and left fore feet.
  7. The right hind foot.
  8. Without support.

It appears somewhat remarkable that until the results of M. Marey's
experiments and of those obtained by electro-photography were published,
many experienced horsemen were of opinion that during the action of
trotting at least one foot of a horse was always in contact with the
ground.

If the entire stride of a trotting horse is divided into two portions,
representing the comparative distances traversed by the aggregate of the
body while the feet are in contact with, and while they are entirely
clear of, the ground; the relative measurements will be found to vary
very greatly, they being contingent upon length of limb, weight, speed,
and other circumstances.

Heavily built horses will sometimes merely drag the feet just above the
surface, but, in every instance of a trot, the _weight_ of the body is
really unsupported twice during each stride (see stride 2, positions 4
and 4D). It sometimes happens that a fast trotter, during the two actions
of a stride, will have all his feet clear of the ground for a distance
exceeding one-half of the length of the entire stride; this elasticity of
movement is however exceptional.

The action of a fast-trotting horse while drawing a vehicle is very
different from his action under the saddle; in the latter case, the hind
legs are kept thrust back for a longer period, and their final forward
movement is much more rapid.


_The Amble._

Assuming our observation of this movement to commence when, during a
stride of about 10 feet, the left hind foot has just struck the ground
slightly to the rear of where the right fore foot is resting; the left
fore leg will be well advanced but still flexed, with the toe pointed
downwards, and the right hind foot having been the last to leave the
ground, will be thrust backwards with the pastern nearly horizontal.

As the right fore foot leaves the ground, the left fore leg is gradually
straightened during its thrust forwards; the right hind foot in the
meantime is gradually advancing, and the horse is supported on the left
hind foot alone.

The left fore foot is now brought to the ground, and the body rests on
the left laterals, with the right laterals suspended between them.

As the left fore leg attains a vertical position, its lateral leaves the
ground, and the support of the body devolves on the left fore foot alone,
the right fore leg being considerably flexed, with the foot in advance of
the left fore leg.

The right hind foot now strikes the ground, and one half of the stride is
accomplished; these movements are repeated with a change of the limbs for
the remaining portion of the stride, and the horse is again in the
position in which we first observed him.

We shall see by reference to stride No. 5 the consecutive supporting feet
to be:

  1. The left hind foot.
  2. The left hind and left fore feet--_laterals_.
  3. The left fore foot.
  4. The left fore and right hind feet--_diagonals_.
  5. The right hind foot.
  6. The right hind and right fore feet--_laterals_.
  7. The right fore foot.
  8. The right fore and left hind feet--_diagonals_.

The right fore foot being raised, the horse is again in the first
position.

The amble and the walk are the only regular progressive movements of the
horse wherein the body is never without the support of one or more legs,
in all others the weight is entirely off the ground for a longer or
shorter period.


_The Rack or Pace._

The rack differs from the trot in the nearly synchronous action of the
_laterals_ instead of the _diagonals_.

In some countries the rack is naturally adopted by the horse as one of
his gaits, but it is probably caused by the effects of training exercised
over many generations of his ancestors.

The movements already described are regular in their action, and a stride
may be divided into two parts, which are essentially similar to each
other.


_The Canter_

and the gallop, however, cannot be so divided, and a complete stride in
either of those gaits is a combination of several different movements.

The canter is usually regarded as a slow gallop, probably from the
facility with which a change from one gait to the other can be effected;
an important difference will, however, be observed.

Assuming a horse after his propulsion through the air, during a stride of
10 feet, to have just landed on his left hind foot, the right hind foot
will be on the point of passing to the front of the left. The left fore
leg will be thrust forward and nearly straight, while the right fore leg
will be flexed with the foot elevated about 12 inches from the ground,
and somewhat behind the vertical of the breast. The left fore foot being
brought to the ground, the body is supported by the laterals; the right
hind foot is, however, quickly lowered, and performs its share of
support. The left hind foot is then raised, and the right hind and left
fore legs assume the weight, the former being nearly vertical, and the
latter inclined well back, the right fore foot is thrust well forward,
and is just about to strike the ground; when it does, three feet again
share the support, they being the two fore and the right hind. The left
fore foot now leaves the ground, and we again find the support furnished
by the laterals, the right instead of, as before, the left.

The right hind foot is raised when the right fore leg becomes vertical;
this latter, which now sustains the entire weight, gives the final effort
of propulsion, and the body is hurled into the air.

The descent of the left hind foot completes the stride, and the
consecutive movements are repeated.

In stride No. 7 we learn that during the canter the support of the body
is derived from

  1. The left hind foot.
  2. The left hind and left fore feet--_laterals_.
  3. Both hind and the left fore feet.
  4. The right hind and left fore feet--_diagonals_.
  5. The right hind and both fore feet.
  6. The right hind and right fore feet--_laterals_.
  7. The right fore foot alone, on which he leaves the ground.


_The Gallop or Run._

This movement has in all ages been employed by artists to convey the
impression of rapid motion, although, curiously enough, the attitude in
which the horse has been almost invariably depicted is one which is
impracticable during uniform progressive motion.

When during a rapid gallop, with a stride of 20 feet, a horse after his
flight through the air lands on his left hind foot, the right hind will
be suspended over it at an elevation of 12 or 15 inches, and several
inches to the rear of and above it the sole of the right fore foot will
be turned up almost horizontally, the left fore leg is flexed with the
foot under the breast at a height of 18 or 20 inches.

The right hind foot strikes the ground some 36 inches in advance of the
left hind, each as they land being forward of the centre of gravity.

The body is now thrust forward, and while the right hind pastern is still
almost horizontal, the left hind foot leaves the ground. At this time the
left fore leg is perfectly straight, the foot, with the toe much higher
than the heel, is thrust forward to a point almost vertical with the
nose, and at an elevation of about 12 inches the right fore knee is bent
at right angles, and the foot suspended under the breast at several
inches greater elevation than the left fore foot.

The left fore foot now strikes the ground, 96 inches in advance of the
spot which the right hind foot is on the point of leaving, and for a
brief space of time the diagonals are upon the ground together. The left
fore leg, however, immediately assumes the entire responsibility of the
weight, and soon attains a vertical position, with its pastern at right
angles to it.

In this position the right hind foot is thrust back to its fullest
extent, at an elevation of 12 or 14 inches, with the pastern nearly
horizontal. The left hind foot is considerably higher and somewhat more
forward; the right fore leg is straight, stretched forward, with the foot
about 15 inches from the ground, and almost on a perpendicular line from
the nose. The right fore foot strikes the ground 48 inches in advance of
the left fore, which, having nearly performed its office, is preparing to
leave the ground; the animal will then be supported on the right fore
foot alone, which immediately falls well to the rear of the centre of
gravity, which is sometimes passed by the left hind foot at a height of
about 12 inches; the right hind foot is some distance in the rear, and
the left fore foot, at a height of 24 inches, is suspended somewhat in
advance of its lateral.

In this position the horse uses the right fore foot for a final act of
propulsion, and is carried in mid air for a distance of 60 inches, after
which the left hind foot descends, the stride is completed, and the
consecutive motions renewed.

The measurements and positions herein given do not pretend to exactness,
as they must depend to some extent upon the capability, training, and
convenience of the animal; but they may be accepted as representing an
average stride of 20 feet with a horse in a fair condition for racing.

From this analysis it will be seen, by reference to stride 9, that a
horse, during an ordinary gallop, is supported consecutively by:

  1. The left hind foot,
  2. Both hind feet,
  3. The right hind foot,
  4. The right hind and left fore feet,
  5. The left fore foot,
  6. Both fore feet,
  7. The right fore foot,

with which he leaves the ground, while the only position in which we find
him entirely without support is when all the legs are flexed under his
body.

It is highly probable, however, that more exhaustive experiments with
long-striding horses in perfect training, will discover there is
sometimes an interval of suspension between the lifting of one fore foot
and the descent of the other; and also between the lifting of the second
hind foot which touches the ground, and the descent of its diagonal fore
foot (see imaginary stride 10). Should this latter be the case, it will,
from the necessary positions of the other limbs, afford but a very
shadowy pretext for the conventional attitude used by artists to
represent a gallop. It is extremely doubtful if there can be any interval
of suspension between the lifting of one hind foot and the descent of the
other, no matter what the length of stride.

Many able scientists have written on the theory of the gallop, but I
believe Marey was the first to demonstrate, that in executing this
movement, the horse left the ground with a fore foot and landed on a hind
foot.


_The Leap._

There is little essential difference in general characteristics of either
of the several movements that have been described, but with a number of
experiments made with horses while leaping, no two were found to agree in
the manner of execution. The leap of the same horse at the same rate of
speed, with the same rider, over the same hurdle, disclosed much
variation in the rise, clearance, and descent of the animal. Apart from
this, the horses were not thoroughly trained leapers, and the results are
perhaps not representative of those that would be obtained from the
action of a well-trained hunting horse. A few motions were, however,
invariable. While the horse was raising his body to clear the hurdle, one
hind foot was always in advance of the other, and exercised its last
energy alone.

On the descent, the concussion was always received by one fore foot,
supported by the other more or less rapidly, and sometimes as much as 30
inches in advance of where the first one struck, followed by the hind
feet also, with intervals of time and distance between their several
falls. It is highly probable future experiments will prove these
observations to be invariable in leaping.

It is highly probable that these photographic investigations, which were
executed with wet collodion plates with exposures not exceeding in some
instances the one five-thousandth part of a second, will dispel many
popular illusions as to gait, and that future and more exhaustive
experiments, with all the advantages of recent chemical discoveries, will
completely unveil to the artist all the visible muscular action of men
and animals during their most rapid movements.

The employment of automatic apparatus for the purpose of obtaining a
regulated succession of photographic exposures is too recent for its
value to be properly understood, or to be generally used for scientific
experiment; at a future time, the pathologist, the anatomist, and other
explorers for hidden truths will find it indispensable for their complex
investigations.


LONDON: PRINTED BY WM. CLOWES AND SONS, LIMITED, STAMFORD STREET AND
CHARING CROSS.





End of the Project Gutenberg EBook of The Attitudes of Animals in Motion, by 
Eadweard Muybridge

*** 