M. Arago's Biographical Memoir of James Watt. 247 



evidently be altogether inadmissible, were the piston required 

 to move with any degree of velocity. Papin remarked, that 

 the end might be obtained " by different constructions which 

 might readily be conceived," but left the constructions en- 

 tirely miexplained. He devolved upon his successors both the 

 merit of applying his pregnant conception, and that of dis- 

 covering those details which alone can ensure the success of a 

 machine. 



In om* earlier researches concerning the employment of 

 steam, we have had occasion to cite the ancient philosophers 

 of Greece and Rome ; one of the most celebrated mechanists 

 of the school of Alexandria ; a Pope ; a courtier of Henry IV. ; 

 and an engineer of Normandy, that province so productive of 

 great men, and which has ornamented our national galaxy 

 of talent, with a Malherbe and a Corneille, a Poussin and a 

 Fontenelle, with Laplace and Fresnel : we have also had to 

 quote an English nobleman ; a British engineer ; and finally 

 a French physician who was a member of the Royal Society of 

 London, for we cannot but confess that Papin, almost always 

 an exile, was nothing more than a coiTesponding member of 

 our own Academy. Siniple artisans and more humble work- 

 men are now about to enter the lists ; and so all classes of 

 society will be found to have contributed their shai'e to the 

 production of a machine by which the whole world was to 

 profit. 



In the year 1705, fifteen years after the publication of 

 Papin's firstmemoir in the Acts of Leipsic, Newcomen and Caw- 

 ley, the one an ironmonger, and the other a glazier in Dai't- 

 mouth, Devonshire, constructed (and mark, I do not say pro- 

 jected, which is a very difi"erent thing), I repeat, constructed 

 a machine, which was meant to raise water from great depths, 

 and in which there was a distinct vessel where the steam 

 was generated. This machine, like the small model of Papin, 

 consisted of a vertical metallic cylinder, shut at the bottom 

 and open at the top, together with a piston, accurately fitted, 

 and intended to traverse the whole length, both in ascending 

 and descending. In the latter, as in the former apparatus 

 also, when the steam was freely admitted into the lower part 

 of the cylinder, so filling it, and counterbalancing the exter- 



