M. Arago*s Historical Eloge of Joseph Fourier. 



ing his mode of procedure, but the deductions from the theory 

 are more general and more important. 



Heat, when concentrated on any point of a solid body, is 

 communicated, by means of conductibility, to the particles 

 nearest the heated point, and afterwards, gradually, to all parts 

 of the body. Hence the problem of which the following is the 

 enunciation : 



" By what methods, and with what velocity, is the propagation 

 of heat effected, in bodies of different forms and natures, when 

 submitted to certain initial conditions ?'' 



The Academy of Sciences had, in fact, already proposed this 

 problem as a subject of a prize in the year 1 736. As the terms 

 of heat and caloric were not employed at that time, it was en- 

 titled " V etude de la nature et de la propagation dujeti /" The 

 word feu thus used in the programme, without any explana- 

 tion, gave rise to a most strange mistake. The greater num- 

 ber of natural philosophers imagined that it was proposed to 

 explain how fire {fincendie) is communicated and increased in 

 a mass of combustible materials. Fifteen competitors appeared, 

 of whom three were successful. 



This competition afforded few results. Nevertheless a sin- 

 gular combination of circumstances and of names of individuals 

 will cause it to be long remembered. 



The public had certainly some reason to be surprised on read- 

 ing the following declaration of the academy : " The question 

 affords scarcely any scope for geometry" ! In regard to inven- 

 tions, the attempt to anticipate futurity, is likely to produce glar- 

 ing mistakes. One of these competitors, however, the great 

 Euler, took these words in a literal sense. The reveries with 

 which his memoir abounds, are not redeemed, on this occasion, 

 by any of those brilliant analytical discoveries, — I had almost 

 said those sublime inspirations which were so common to him. 

 Fortunately, Euler added to his memoir, a supplement truly 

 worthy of him. Father Lozeran de Fiesc and Count de CrSqm^ 

 had the high honour of seeing their names mentioned along 

 with that of the illustrious geometrician, although it is impos- 

 sible now to discover in their memoirs any kind of merit, 

 even that of politeness ; for the courtier has the rudeness to say 



