In his final year of school, Tolkien wrote an inscription in Gothic in his copy of Graves' Fifth Book of Thucydides.
Letter 272 is Tolkien's response to Zillah Sherring who had purchased the book from a second-hand bookshop in Wiltshire, had noticed Tolkien's name, and had written to him with a transcription of the Gothic inscription (shown here):
Here is my transcription and interlinear gloss along with some explanations and Tolkien's own translation and comments from Letter 272.
IK LAS ÞŌ WAVRDA ÞIZO BOKO HELENIKSAIZOS JERAMELEINAIS
I.NOM.SG gather.PRET.1SG this.ACC.PL word.ACC.PL this.GEN.PL book.GEN.PL Greek.GEN.SG year-writing.GEN.SG
las (I gathered) is used to mean ‘read’ by analogy with other Germanic languages.
Note ÞIZO BOKO (GEN.PL) was probably meant to be ÞIZŌS BŌKŌS (GEN.SG) (per Tolkien's letter)
I believe JERAMELEINAIS is a coinage of Tolkien's:
jēr = year;
mēljan = to write;
-ein- = abstract noun from weak verb;
-áis GEN.SG
HELENIKSAIZOS might be too.
‘I read the words of this book of Greek history’
IN ÞAMMA MENOÞ SAIHSTIN ÞIS JERIS ÞŪSUNDI NIVN HVNDAI TAIHVN UNSARIS FRAUJINS
HVNDAI should be HVNDA (per Tolkien's letter)
in this.DAT.SG month.DAT.SG sixth.DAT.SG this.GEN.SG year.GEN.SG thousand nine hundred ten our.GEN.SG Lord.GEN.SG
‘in the sixth month of this year: thousand, nine hundreds, ten, of our Lord’
DUÞE IK BIGETJAU ÞATA LAVN GIBAN ALLIS JERIS ÞAMMA MAGAV MAIST KVNNANDIN BI ÞŪKYDIDJA
so.that I.NOM.SG meet-with.PRET.SUBJ.1SG this.ACC.SG reward.ACC.SG give.? every.GEN.SG year.GEN.SG this.DAT.SG boy.DAT.SG most know.PRES.PART.DAT.SG about Thucydides.DAT.SG
‘in order to gain the prize given every year to the boy knowing most about Thucydides’
JAH HITA ANAMELIDA IN BOKOS MEINOS ÞAMMA TWALIFTIN ÞIS SAIHSTINS AFARÞIZEI IK JU FRUMINS ÞAIRHLESJAU ALLA ÞO WAVRDA GLAGGWVBA
FRUMINS is probably an error for FRUMIST (per Tolkien's letter)
and this.ACC.SG down-write.PRET.1SG in book.ACC.PL my.ACC.PL this.DAT.SG twelfth.DAT.SG this.GEN.SG sixth.GEN.SG after-which.GEN.SG I.NOM.SG already first* through-read.PRET.SUBJ.1SG all this.ACC.PL word.ACC.PL carefully
BOKOS MEINOS (ACC.PL) is probaby an error for BOKA MEINA (ACC.SG) (per Tolkien's letter)
‘and this I inscribed in my books on the twelfth of the sixth (month) after I had already ? first read through all the words carefully.’