4 o 4 THE POPULAR SCIENCE MONTHLY. 



first paper on the ' Mechanical Value of Heat,' in 1843 ; but in 1842 

 Mayer had actually calculated the mechanical equivalent of heat from 

 data which a man of rare originality alone could turn to account. 

 From the velocity of sound in air, Mayer determined the mechanical 

 equivalent of heat." 



In October of the same year there appeared an article in " Good 

 Words," under the title of " Energy," the joint production of Profes- 

 sors Thomson and Tait, which was called forth by Tyndall's June lec- 

 ture on "Force." In this paper and in subsequent ones, defending it, the 

 writers confess themselves startled at the recent attempt made "to 

 place Mayer in a position which he never claimed," and they deny to 

 him " the credit of being the first to establish in its generality the prin- 

 ciple of the ' Conservation of Energy,' " and assert that " Mayer's paper 

 (1842) has no claims to novelty or correctness at all, saving this, that 

 by a lucky chance he got an approximation to a true result from an 

 utterly false analogy " ; and that " even on this point he had been anti- 

 cipated by Seguin, who three years before the appearance of Mayer's 

 paper had obtained and published the same numerical result from the 

 same hypothesis. " They claim that the honors of producing this the- 

 ory are English throughout; that Newton, Rumford, and Davy estab- 

 lished it, and that Dr. Joule, of Manchester, developed and matured it ; 

 and, impelled by a proper " scientific patriotism," they protest against 

 this attempt of Tyndall to make over to a foreigner what belongs 

 to his own countrymen, and is withheld by depreciation and sup- 

 pression. 



These positions were met and the whole case of Professors Thomson 

 and Tait exploded in a series of communications addressed by Profes- 

 sor Tyndall to the " Philosophical Magazine." As to the statement 

 that Mayer himself did not claim to be a founder of the " Dynamical 

 Theory of Heat," Professor Tyndall quoted the following passage from 

 a publication of Mayer's in 1851 : " The new subject " (the mechanical 

 theory of heat) " soon began to excite the attention of learned men, but, 

 inasmuch as both at home and abroad the subject has been exclusively 

 treated as a foreign discovery, I find myself compelled to make the 

 claims to which priority entitles me ; for, although the few investiga- 

 tions which I have given to the public, and which have almost disap- 

 peared in the flood of communications which every day sends forth, 

 without leaving a trace behind, prove by the very form of their publica- 

 tion that I am not one who hankers after effect, it is not therefore to 

 be assumed that I am willing to be deprived of intellectual property 

 which documentary evidence proves to be mine." 



As to the declaration that Mayer's views of 1842 had no novelty or 

 correctness at all, save what he luckily blundered into, Professor Tyn- 

 dall first quotes some counter-authorities. In Professor Helmholtz's 

 celebrated discourse, delivered at Konigsberg, in 1854, on the interac- 

 tion of natural forces, this great physicist remarks, " The first man who 



