g now in the confessional, I must own that I did not, at the
moment, recognize the marked intellectuality of a very striking face.
As a representation of a mathematician in the throes of thought,
I know nothing to equal his portrait by Dickenson, which now hangs
in the hall of Trinity College, Cambridge, and is reproduced in the
sixth volume of Cayley's collected works. His life was that of a
man moved to investigation by an uncontrollable impulse; the only
sort of man whose work is destined to be imperishable. Until forty
years of age he was by profession a conveyancer. His ability was
such that he might have gained a fortune by practicing the highest
branch of English law, if his energies had not been diverted in
another direction. The spirit in which he pursued his work may
be judged from an anecdote related by his friend and co-worker,
Sylvester, who, in speaking of Cayley's even and placid temper,
told me that he had never seen him ruffled but once. Entering his
office one morning, intent on some new mathematical thought which
he was discussing with Sylvester, he opened the letter-box in his
door and found a bundle of papers relating to a law case which he
was asked to take up. The interruption was too much. He flung the
papers on the table with remarks more forcible than complimentary
concerning the person who had distracted his attention at such an
inopportune moment. In 1863 he was made a professor at Cambridge,
where, no longer troubled with the intricacies of land tenure, he
published one investigation after another with ceaseless activity,
to the end of his life.

Among my most interesting callers was Professor John C. Adams, of
whom I have spoken as sharing with Leverrier the honor of having
computed the position of the planet Neptune before its existence
was otherwise known. The work of the two men was prosecuted at
almost the same time, but adopting the principle that priority of
publication should be the sole basis of credit, Arago had declared
that no other name than that of Leverrier should even be mentioned
in connection with the work. If repute was correct, Leverrier was
not distinguished for those amiable qualities that commonly mark the
man of science and learning. His attitude toward Adams had always
been hostile. Under these conditions chance afforded the latter
a splendid opportunity of showing his superiority to all personal
feeling. He was president of the Royal Astronomical Socie