284 GREAT MEN OF SCIENCE 



that the blood was bright red, although it was not taken from 

 an artery. This was the great event in Mayer's life; from 

 this point everything that he had hitherto considered took on 

 a new form in his thoughts; causes and effects appeared to 

 him quite suddenly to enter into hitherto unknown con- 

 nections. He then began for the first time - in the autumn 

 of 1840 at Surabaya in Java -to think, in the manner to 

 which we are accustomed to-day, about the energy principle. 

 The whole hundred and twenty-one days of the voyage home 

 obviously found him without anything else in his miind; for 

 his diary, which on the journey out reports in detail all 

 events on the ship and concerning the weather, is now com- 

 pletely silent, and a few months after his return he had 

 completed a first draft on the subject. ^ But he continued 

 uninterruptedly to work on the matter, pressing forward with 

 ever increasing clarity, up to the statement of 1842, which 

 appeared in Liebig's Annalen as the first public announce- 

 ment of his thoughts. 2 We finally have the complete state- 

 ment of 1845, which represents the highest point of his 

 achievement in scientific research. 



In the same year, after returning from the journey, Mayer 

 took a house in his native town. He soon became the best- 

 known doctor there, and had already married in 1842 the 

 daughter of a well-to-do merchant. The following and no 

 doubt happiest period of his life did not last long. We have 

 already told above of the unhappy experiences which then 

 overtook him. According to all trustworthy accounts^ it 

 was most of all the great mental isolation which Mayer 



1 He sent it to Poggendorf for the Annalen der Physik, where it re- 

 mained pigeon-holed. 



2 See his letters of this period (Weyrauch, Kleinere Sthriften und 

 Brief e von J. R. Mayer, Stuttgart, 1893). 



3 See the collection of contemporary reports, together with Robert 

 Mayer's own notes, in Weyrauch's edition of the Mechamk der Wdrme 

 (1893"), pp. 303-309, and also the report on Mayer's meeting - 25 years 

 after his treatment in the mad-house - with E. Duhring, in the latter's 

 book Robert Mayer, der Galilei des 19. Jahrhunderts (2nd Ed., Leipzig), 

 pp. 132-171. 



