THE MASTER WORKER 



then heated, it would acquire a capacity to take up 

 more vapor, and so long as this capacity was latent, the 

 vapor present would exist in a super-heated condition. 



It will be understood from what has been said 

 before, that with all accessions of heat, the expansive 

 power of the vapor is increased, its molecules be- 

 coming increasingly active ; hence one of the very ob- 

 vious advantages of super-heated steam for the purpose 

 of pushing a piston. There are other advantages, 

 however, which are not at first sight so apparent, 

 having to do with the properties of condensation. To 

 understand these, we must pay heed for a few moments 

 to the changes that take place in steam itself in the course 

 of its passage through the cylinder, where it performs its 

 work upon the piston. 



Many of these changes were not fully understood by 

 the earlier experimenters, including Watt. Indeed the 

 theory of the steam engine, or rather the general theory 

 of the heat engine, was not worked out until the year 

 1824, when the Frenchman Carnot took the subject in 

 hand, and performed a series of classical experiments, 

 which led to a nearly complete theoretical exposition 

 of the subject. It remained, however, for the students of 

 thermo-dynamics, about the middle of the nineteenth 

 century, with Clausius and Rankine at their head, to 

 perfect the theory of the steam engine, and the general 

 subject of the mutual relations of heat and mechanical 

 work. 



We are not here concerned with any elaboration of 

 details, but merely with a few of the essential principles 

 which enter practically into the operation of the steam 



[us] 



