114 



SCIENTIFIC THOUGHT. 



facts, 1 and that the then reigning school of natural philos- 

 ophers in Germany discouraged theoretical deductions, as 

 possibly leading back to the fatal " philosophy of nature," 

 out of which they had only just escaped. Men of the 

 intellectual eminence of Liebig, through whose labours an 

 enormous mass of new facts had been accumulated, and 

 who desired to see the more hidden processes of organic 

 life subjected likewise to rigorous measurements, showed 

 indeed a certain appreciation of the attempted defini- 

 tions of Mohr and Mayer, struggling as he and 

 they alike were under the still existing confusion in 

 the fundamental conceptions. 2 And these were not 



1 See Mohr, ' Allgeineine Theorie 

 der Bewegung und der Kr(ft,' p. 

 82, &c. Poggendorf did not reply 

 to Mayer's repeated communica- 

 tions and did not return the MS. ; 

 the fact that he received it was first 

 established by Zollner, who in 1877 

 recovered the MS. from Poggen- 

 dorf 's heirs (Mayer's ' Schriften und 

 Briefe,' ed. Weyrauch, p. 100), and 

 gave a facsimile of it in his 

 ' Wissenschaftliche Abhandlungen ' 

 (Leipzig, vol. iv., 1881, p. 672). 

 Helmholtz, who in 1847 had no 

 knowledge of Mayer's writings, did 

 full justice to his claims in his 

 address, ' Ueber die Wechselwirk- 

 ung der Naturkrafte ' (1854), and 

 vindicated them against Tait's 

 criticisms in a letter published by 

 the latter in his ' Sketch of Ther- 

 modynamics' (Edinburgh, 1868); 

 see Helmholtz, ' Wissenschaftliche 

 Abhandlungen,' vol. i. p. 71, &c. 

 Helmholtz closes his later com- 

 ments on the subject (' Vortriige 

 und Reden,' vol. i., 3rd ed., 1884, p. 

 74) with the following significant 

 remark : ' ' The best ideas run the 

 risk of remaining barren, if not 

 accompanied by that energy which 

 lasts till the convincing proof of 



their correctness has been given." 

 This explains the neglect of Mohr 

 and Mayer, and why in England 

 the interest in the energy ideas 

 only became general after Joule's, 

 Thomson's, and Rankine's labours, 

 as Helmholtz himself remarks in 

 1854 ('Vortrage,' &c., p.- 39). 



^ Helmholtz (" Ueber Mayers 

 Prioritat," 'Vortrage,' vol. i. p. 69) 

 says : " That the [i.e. Mayer's] dis- 

 sertation contained really important 

 ideas, that it did not belong to the 

 wide-ranging literature of vague 

 suggestions, such as are annually 

 served up by badly informed ama- 

 teurs, could at best only be noticed 

 by a reader who had already turned 

 over in his mind similar reflections, 

 and who could recognise them 

 under the somewhat strange vocabu- 

 lary of the author. Liebig, who, in 

 the same year in which Mayer's 

 dissertation appeared, published his 

 book on animal chemistry, in which 

 he fully discussed the question as to 

 the origin of animal heat, was per- 

 haps such a reader, and was there- 

 fore willing to insert the article 

 in his annals." The same remark 

 would refer equally to Mohr's 

 earlier essay. It is now known 



