PAPIN'S MODEL ENGINES. 383 



The machine in which our countryman was the first to 

 combine the elastic force of steam with the property pos- 

 sessed by this vapour of annihilating itself by cooling, he 

 never made on a large scale. His experiments were 

 always made with simple models. The water intended 

 to generate the steam was not even contained in a separ- 

 ate vessel ; enclosed in the cylinder, it rested on the 

 metal plate that closed the orifice at the bottom. It was 

 this plate that Papin heated directly, to transform the 

 water into steam ; it was from the same plate that he 

 took away the fire when he wished for condensation to 

 be effected. Such a proceeding, barely allowable in an 

 experiment intended to verify the correctness of a prin- 

 ciple, would evidently be still less admissible if the piston 

 were required to move with some celerity. Papin, whilst 

 saying that success might be attained " by various con- 

 structions easy to imagine," does not indicate any of them. 

 He leaves to his successors both the merit of applying 

 his fruitful idea, and that of inventing the details, which 

 alone could ensure the success of the machine. 



In our early researches respecting the employment of 

 steam, we have had to quote ancient philosophers of 

 Greece and Rome ; one of the most celebrated mechanics 

 of the Alexandrian school ; a pope ; a gentleman of the 

 court of Henri IV. ; a hydraulist, born in Normandy (in 

 that province fruitful in great men, that has enriched 

 the national Pleiad with Malherbe, Corneille, Poussin, 

 Fontenelle, Laplace, and Fresnel) ; a member of the 



water in one and the same machine, as an elastic power and as a rapid 

 means of forming a vacuum, belonged to Hero. On my side I have, 

 proved, unanswerably, that the Alexandrian mechanic had never 

 thought of steam ; that in his apparatus the alternate movement was 

 to result only from the dilatation and the condensation of air, arising 

 from the intermittent action of the solar rays. 



