160 JOSEPH FOURIER. 



declaratiou : " The question affords do handle to geometiy ! " In matter 

 of inventions, to attempt to dive into the future is to prepare for one's self 

 striking mistakes. One of the competitors, the great Euler, took these 

 words in their literal sense: the reveries with which his memoir abounds 

 are not compensated in this instance by any of those brilliant discover- 

 ies in analysis — I had almost said of those sublime inspirations — which 

 Averc so familiar to him. Fortunately Euler appended to his memoir a 

 sui>plement truly worthy of his genius. Father Lozeran dc Fiesc and 

 the Count of Crequi were rewarded with the high honor of seeing their 

 names inscribed beside that of the illustrious geometer, although it 

 would be impossible in the present day to discern in their memoirs any 

 kind of merit, not even that of politeness, for the courtier said rudely 

 to the Academy : " The question which you have raised interests only 

 the curiosity of mankind." 



Among the competitors less favorably treated, we preceive one of the 

 greatest writers whom France has produced — the author of the Hcnriade. 

 The memoir of Voltaire was, no doubt, far from solving the problem 

 proposed ; but it was at least distinguished by elegance, clearness, and 

 precision of language 5 I shall add, by a severe style of argument ; for 

 if the author occasionally arrives at questionable results, it is only when 

 he borrows false data from the chemistry and physics of the epoch, — 

 sciences which had just sprung into existence. Moreover, the anti- 

 Cartesian color of some of the parts of the memoir of Voltaire was cal- 

 cidated to find little favor in a society where Cartesianism, with its 

 incomprehensible vortices, was everywhere held in hiigh estimation. 



We should have more difticulty in discovering the causes of the failure 

 of a fourth competitor, Madame the Marchioness du Chatelet, for she 

 also entered into the contiest instituted by the Academy. The work of 

 Emilia was not only an elegant portrait of all the in-operties of heat 

 known then to physical inquirers ; there were remarked, moreover, in it 

 different projects of experiments, among the rest, one Avhich Herschel 

 has since developed, and from which he has derived one of the principal 

 llowers of his brilliant scientific crown. 



While such great names were occupied in discussing this question, 

 physical inquirers of a less ambitious stamp laid experimentally the solid 

 basis of a future mathematical theory of heat. Some established that 

 the same quantity of caloric does not elevate by the same number of 

 degrees equal weights of different substances, and thereby introduced 

 into the science the important notion of cajyacity. Others, by the aid of 

 observations no less certain, proved that heat, applied at the extremity 

 of a bar, is transmitted to the extreme parts with greater or less velocity 

 or intensity, according to the nature of the substance of which the bar 

 is composed : thus they suggested the original idea of conductiUUiy. The 

 same epoch, if I were not precluded from entering into too minute 

 details, would present to us interesting exi)erinu'nts. We should find 

 that it is not true that, at all degrees of the,thermometer, the loss of 



