382 FRAGMENTS OF SCIENCE. 



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 in- 

 formation which I needed.* Both of them are Ger- 

 mans, and both particularly distinguished in connec- 

 tion with the Dynamical Theory of Heat. Each of 

 them kindly furnished me with the list of Mayer's pub- 

 lications, 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 re- 

 garding Mayer, stated his belief that I should not find 

 anything very important in Mayer's writings; but be- 

 fore forwarding the memoirs to me he read them him- 

 self. His letter accompanying them contains the fol- 

 lowing 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 im- 

 portant subjects, in the treatment of which Mayer had 

 anticipated other eminent writers. My other friend, 

 in whose own publications the name of Mayer repeat- 

 edly occurs, and whose papers containing these refer- 

 ences 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 

 'Beitrage zur Dynamik des Himmels/ and in 1854, 

 when Professor William Thomson developed in so 

 striking a manner the meteoric theory of the sun's 

 heat, he was certainly not aware of the existence of 



* Helmholtz and Clausius. 



