402 FRAGMENTS OF SCIENCE 



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 de- 

 sire to know what has become of this man. His mind, 

 it is alleged, gave way; it is said he became insane, and 

 lie was certainly sent to a lunatic asylum. In a biograph- 

 ical 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. 



JCNE 20, 1862. 



While preparing for publication my last course of lec- 

 tures on Heat, I wished to make myself acquainted with 

 all that Dr. Mayer had done in connection with this sub- 

 ject I accordingly wrote to two gentlemen who above all 

 others seemed likely to give me the information which 

 I needed. 1 Both of them are Germans, and both par- 

 ticularly 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 (Clau- 

 sius) 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 fol- 

 lowing words: "I must here retract the statement in my 



1 Helmholtz and Clausius. 



