30 HEROES OF INVENTION AND DISCO VERY. 



under the piston have been rendered quite perfect, and all ob- 

 structions from friction annihilated, could only have amounted 

 to about fifteen pounds for every square inch of the surface 

 of the piston. The expansive force of steam was not, in fact, 

 at all employed in this contrivance as a moving power ; could 

 the vacuum necessary to permit the descent of the piston have 

 been as expeditiously and conveniently produced by any other 

 agency, that of steam might have been dispensed with alto- 

 gether. An air-pump, for instance, attached to the lower part 

 of the cylinder, as originally proposed by Otto Guericke, might 

 have rendered all the service which steam was here called upon 

 to perform ; and in that case, this element, with the fuel by 

 which it was generated, might have been dispensed with, and 

 the machine would not have been a steam-engine at all. This 

 view of the matter may, in some degree, account for the com- 

 plete neglect of steam as a moving power which so long pre- 

 vailed after Newcomcn's engine was brought into use, notwith 

 standing the proofs of its capabilities in that character which 

 had been afforded by the attempts of the earlier speculators. 

 It was now regarded simply as affording the easiest means of 

 obtaining a ready vacuum, in consequence of its property of 

 rapid condensation on the application of cold ; its other pro- 

 perty of extraordinary expansion, which had first attracted to it 

 the attention of mechanicians, and presented in reality a much 

 more obvious aj)plication of it as a mechanical agent, had been 

 entirely neglected. The only improvements of the engine 

 which were attempted or thought of were such as referred to 

 what may be called its subordinate mechanism, — that is to say, 

 the contrivances for facilitating the alternate supplies of the 

 steam and the water on which its action depended ; and after 

 Mr. Beighton had, about tlie year 1718, made the machine 



