THE CONDENSF.K INTKOIM OKO. &amp;gt; 1 J 1 



soon as it enters ; all the steam which before filled the 

 cylinder will be gradually annihilated ; tho cylinder will 

 thus be cleared of steam without its sides being in the 

 least cooled, and the fresh supply of steam, with which 

 it will require to be fillod, will not lose any of its elas 

 ticity. 



The condenser attracts to itself all tho stoain contained 

 in the cylinder, partly because it contains some cold 

 water, and partly because is contains no clastic tluids ; 

 but as soon as some steam has been condensed, those two 

 conditions on which success depended have disappeared ; 

 the condensing water has become hot by absorbing tho 

 latent calorie of tho steam ; a considerable portion of 

 steam has been generated at the expense of that hot 

 water ; tho cold water contained besides some atmos 

 pheric air which mn&amp;gt;t have been disengaged during its 

 heating. If this hot water was not carried away after 

 each operation, together with the steam and the air con 

 tained in the condenser, in the end no effect would be 

 produced. Watt, therefore, attains this triple purpose by 

 the aid of a common pump, called an air-pump, and the 

 piston of which carries a rod suitably attached to tho 

 beam worked by the engine. The power intended to 

 keep tho air-pump in motion, diminishes by that much 

 the power of the engine ; but it is only a small portion of 

 the loss that was occasioned, in the old arrangement, by 

 the steam being condensed on the refrigerated surface of 

 the body of the engine. 



Still another invention by Watt deserves a word, tho 

 advantages of which will he-come evi.lnn to everybody. 



When the piston descends in Newcomen s engine, it is 

 by the weight of the atmosphere. The atmosphere is 

 cold, hence it must cool the sides of the metal cylinder, 



