e, animated solely by a love of his subject,
and arriving at the most important results in advance of those whose
lives were entirely devoted to Natural Philosophy. It was the
accident of bleeding a feverish patient at Java in 1840 that led Mayer
to speculate on these subjects. He noticed that the venous blood in
the tropics was of a brighter red than in colder latitudes, and his
reasoning on this fact led him into the laboratory of natural forces,
where he has worked with such signal ability and success. Well, you
will desire to know what has become of this man. His mind, it is
alleged, gave way; it is said he became insane, and he was certainly
sent to a lunatic asylum. In a biographical dictionary of his country
it is stated that he died there, but this is incorrect. He recovered;
and, I believe, is at this moment a cultivator of vineyards in
Heilbronn.

====================

June 20, 1862.

While preparing for publication my last course of lectures on Heat, I
wished to make myself acquainted with all that Dr. Mayer had done in
connection with this subject. I accordingly wrote to two gentlemen
who above all others seemed likely to give me the information which I
needed. [Footnote: Helmholtz and Clausius.] Both of them are Germans,
and both particularly distinguished in connection with the Dynamical
Theory of Heat. Each of them kindly furnished me with the list of
Mayer's publications, and one of them [Clausius] was so friendly as to
order them from a bookseller, and to send them to me. This friend, in
his reply to my first letter regarding Mayer, stated his belief that I
should not find anything very important in Mayer's writings; but
before forwarding the memoirs to me he read them himself. His letter
accompanying them contains the following words: 'I must here retract
the statement in my last letter, that you would not find much matter
of importance in Mayer's writings: I am astonished at the multitude of
beautiful and correct thoughts which they contain;' and he goes on to
point out various important subjects, in the treatment of which Mayer
had anticipated other eminent writers. My other friend, in whose own
publications the name of Mayer repeatedly occurs, and whose papers
containing these references were translated some years ago by myself,
was, on the 10th of last month, unacquainted with the thoughtful and
beautiful essay of Mayer's, entitled 'Beitraege zur Dynamik des
Himmels,' and in 1854, w