HISTORY OF THE CONSERVATION OF ENERGY 101 



The local press would at first have nothing to do with it. One 

 paper refused to give even a notice of it. The Manchester Courier, 

 after long debate, published the address in full. In June, 1847, the 

 subject was presented before the British Association meeting at Oxford. 

 The chairman suggested that the author be brief. ISTo discussion was 

 invited. In a moment the section would have passed on to other mat- 

 ters without giving the new ideas any consideration, if a young man 

 had not risen from his seat and by his intelligent observations created 

 a lively interest in the new theory. The young man was William 

 Thomson, now better known as Lord Kelvin. The result was that the 

 paper caused a great sensation. Joule had attracted the attention of 

 scientific men. After the meeting Joule and Thomson discussed the 

 subject further and the latter obtained ideas he had never had before. 



Joule experimented on the mechanical equivalent of heat for about 

 forty years. By magneto-electric currents he got in 1843 the value 

 of 460 kilogrammeters as the equivalent of the large French calorie. 

 By the friction of water in tubes he obtained 424.9; by the compres- 

 sion of air, in 1845, 443.8; by the friction of water he obtained, in 

 1845, 488.3; 'in 1847, 428.9; in 1850, 423; in 1878, 423. 



Comparing Joule with Mayer, it will probably be admitted now- 

 adays that Joule stands first as an experimentalist, while Mayer towers 

 above Joule as a generalizer, as a physical philosopher. 



The same year, 1847, in which Joule announced his views on energy 

 before the British Association, Helmholtz, a youth of 26, read before 

 the Physical Society in Berlin a *paper on the same subject, entitled, 

 " Die Erhaltung der Kraft." It was at first pronounced a fantastic 

 speculation. The editor of Poggendorff's Annalen, who in 1841 de- 

 clined Mayer's paper, rejected Helmholtz's also. As Joule was sup- 

 ported by William Thomson, so- Helmholtz was defended by his fellow- 

 student Du Bois-Beymond, and by the mathematician C. G. J. Jacobi. 

 Helmholtz's paper was published in pamphlet form in 1847. For a 

 time it attracted little notice, but in 1853 some parts in it were vigor- 

 ously attacked by Clausius in Poggendorff's Annalen. Later it sub- 

 jected its author to bitter attacks from Eugen Karl Diihring 13 and 

 others, who accused him of being a dishonest borrower from his fore- 

 runner, Bobert Mayer. In a publication of 1898, issued in Berlin, 

 Dr. Thomas Gross does not quite accuse Helmholtz of plagiarism, but 

 claims that Helmholtz did all he could to discredit Mayer. In my 

 judgment both Diihring and Gross failed to establish their contentions. 

 In the absence of clear evidence to the contrary we prefer to accept 

 Helmholtz's own statement, as given in one of his lectures. Helm- 

 holtz says in one place, " The first who saw truly the general law here 



13 Dr. E. K. Diihring, " Robert Mayer, der Galilei des Neunzehnten Jahrhun- 

 derts," Chemnitz, 1880; Zweiter Theil, Leipzig, 1895. 



