AND SURFACE CONDENSKK. 343 



high-pressure superheated steam, surface con- 

 densation, absence of feed and condensing water, and 

 return of the heat, in other engines wasted in condensa- 

 tion, to the fire-place; though there is little or no mention 

 of the mechanical or moving parts of the steam-engine, 

 yet its vital principles are grasped with the hand of a 

 master. The sketch in the letter hastily made forty 

 years ago is more ingenious than any portable engine 

 since constructed, though there may be no sufficient 

 proof of its practical success. The propeller to be 

 worked by this novel engine was of course his long-idle 

 screw. 



Steam Engines, %lst February, 1831. 



"Now KNOW YE, that in compliance with the said proviso, I, 

 the said Richard Trevithick, do declare that the essential points 

 in my improved steam-engine, for which I claim to be the first 

 and true inventor, are : 



"Firstly, the placing of the boiler within the condenser, in 

 order to obtain the additional security of the strength of the 

 condenser to prevent mischief in case the boiler should burst, 

 and also by the same arrangement to conveniently make the 

 condenser, with a very extensive surface, enabling me to con- 

 dense the steam without injecting water into it. 



" Secondly, the enclosing of the condenser in an air or water 

 vessel, by which the intention of safety from explosion is 

 further provided for, and my engine really rendered what I 

 denominate it, a high-pressure safety engine. 



" Thirdly, the condensing of the steam in the condenser by 

 means of a current of cold air or cold*water forced against the 

 outsides of the condenser. 



"Fourthly, the returning of the condensed steam from the 

 condenser back again into the boiler, to the end that sediment 

 and concretion in the boiler may be prevented ; and, 



"Fifthly, the blowing of the fire with the air after it has 

 been heated by condensing the steam. 



" In forming my improved steam-engine I employ several or 



2 A 2 



