JANUARY 4, 1884.] 
tific studies. He had been fascinated by tele- 
scopic views of the planets, and had visited the 
Royal observatory at Dunsink. Unquestion- 
ably one of the most important events in his 
early career was the meeting of Zerah Col- 
burn. The two had engaged in trials of arith- 
metical skill when the former was only twelve ; 
but two years later they re-met, Hamilton be- 
ing ‘‘ not so much the antagonist as the critic 
and the investigator of the methods of the 
gifted computist.’’ That it would be difficult 
to over-estimate the significance of this occur- 
rence is evident from a letter by Hamilton to 
his cousin Arthur, in 1822, wherein he says 
(p- 111), ae 
‘‘T was amused this morning, looking back on the 
eagerness with which I began different branches of 
the mathematics, and how I always thought my pres- 
ent pursuit the most interesting. I believe it was 
seeing Zerah Colburn that first gave me an interest 
in those things. Fora long time afterwards I liked to 
perform long operations in arithmetic in my mind; 
extracting the square and cube root, and everything 
that related to the properties of numbers. It is now 
a good while since I began Euclid. Do you remem- 
ber when I used to go to breakfast with you, and we 
read two or three propositions together every. morn- 
ing? Iwas then so fond of it, that, when my uncle 
wished me to learn algebra, he said he was afraid I 
would not like its uphill work, after the smooth and 
easy path of geometry. However, I became equally 
fond of algebra, though I never mastered some parts 
of the science. Indeed, the resources of algebra have 
probably not been yet exhausted.’’ 
The practical bent of his young mind in 
scientific matters is interestingly shown by his 
invention of a telegraphic signal-code, which, 
for a youth of fifteen, is not a little remark- 
able. The letters of the alphabet were first 
arranged in the following scheme (p. 88) : — 
ie, 2 te igste 5 
vy A B OC DF 
ee 
Ppteee br od 
4 Ou eS Ok 
Ma RE REY 
Twice U = W 
Then five readily distinguishable positions | 
of the arms were chosen. Each letter, thus, 
would be indicated, after the manner of a 
double-entry table, by its position at the inter- 
section of a horizontal and a vertical column ; 
and the numbers of these intersecting columns, 
transmitted from one station to the other by 
SCIENCE. 21 
the pre-arranged signals, would thus spell out 
any desired message. It will be observed that 
the duplication of any given position of the 
arms always indicates a vowel. ‘This device 
for communicating at a distance was for a time 
practically employed by Hamilton and a play- 
mate of his, each being provided with a tele- 
scope, so that he could readily discern the 
successive positions of the arms of the other. 
His devotion to astronomy had by this time 
taken firm hold ; and Hamilton realized this so 
fully himself, that he forcibly made in his stud- 
ies a ‘sudden transition to natural philosophy,’ 
excusing himself therefor to his friends by ex- 
plaining that the ‘‘ intention was to prevent 
my giving up too much time to astronomy by 
diverting my thoughts to another channel: 
‘atqui emovit veterem mire morbus novus,’ for 
I am now as deeply engaged in the study of 
pendulums.’’ In a short paper, at the age 
of sixteen, he brings science to the assistance 
of the classics, finding astronomical calculation 
to help in the decision of a moot-point in the 
chronology of the Aeneid. 
It is most interesting to follow the growth 
of Hamilton’s young mind as his fondness for 
the mathematics increased, and his devotion to 
the classics waned. His pre-collegiate letters 
abound in passages evincing the radical change 
which was going on, and the solid permanency 
with which his new favorites had taken posses- 
sion. A passage from a letter to his sister 
Eliza, shortly after his entering Trinity college, 
is cited here as a vigorous illustration of 
this : — 
‘One thing only have I to regret in the direction 
of my studies, that they should be diverted — or 
rather, rudely forceed—by the college course from 
their natural bent and favorite channel. ‘That bent, 
you know, is science —science in its most exalted 
heights, in its most secret recesses. It has so capti- 
vated me — so seized on, I may say, my affections — 
that my attention to classical studies is an effort, and 
an irksome one.”’ 
Immediately on abandoning his absorbing 
interest in the classics, his work of original 
research in mathematical optics began. Mr. 
Graves quotes the title of an ‘* Essay on equa- 
tions representing systems of right lines in 
a given plane,’’ etc.,—a paper of twenty- 
one folio pages, to which Hamilton himself 
had appended the following note: ‘* (This 
curious old paper, found by me to-day in 
settling my study, must have been written at 
least as early as 1822. It contains the germ 
of my investigations respecting Systems of 
rays, begun in 1823. W. R. H., February 
27, 1834.)”’ 
