THE WORK OF SADI CARNOT, 17 



of a triple-expansion engine, a type which is to- 

 day just coming into use, more than a half -cen- 

 tury after Carnot/s date. He recognizes the ad- 

 vantages of the compound engine in better distri- 

 bution of pressures and in distribution of the work 

 of expansion, but does not, of course, perceive the 

 then undiscovered limitation of the efficiency of 

 the simple engine, due to ' ' cylinder condensation," 

 which has finally led, perhaps more than any other 

 circumstance, to its displacement so largely by 

 the multi-cylinder machine. No one has more ex- 

 actly and plainly stated the respective advantages 

 to be claimed for air and the gases, used as work- 

 ing fluids in heat-engines, than does Carnot ; nor 

 does any one to-day better recognize the difficul- 

 ties which lie in the path to success in that direc- 

 tion, in the necessity of finding a means of hand- 

 ling them at high temperatures and of securing 

 high mean pressures. 



His closing paragraph shows his extraordinary 

 foresight, and the precision with which that won- 

 derful intellect detected the practical elements 

 of the problem which the engineer, from the days 

 of Savery, of Newcomen, and of Watt, has been 

 called upon to study, and the importance of the 

 work, which he began, in the development of a 

 theory of the action, or of the operation, of the 



