106 POLE STEAM-ENGINE. 



Watt low-pressure engine, thereby more than doubling 1 

 its economical duty. 



In 1813 Trevithick wrote: 



" That new engine you saw near the sea-side with me (Wheal 

 Prosper high-pressure pole condensing engine) is now lifting 

 forty millions one foot high, with a bushel of coal, which is 

 nearly double the duty that is done by any other engine in the 

 county. A few days since I altered a 60-inch cylinder engine at 

 Wheal Alfred to the same plan, and I think she will do equally as 

 much duty. I have a notice to attend a mine meeting, to erect 

 a new engine equal in power to a 63-inch cylinder single." 1 



In the four or five years from bis return to Cornwall 

 in 1810, to bis leaving for South America in 1816, he 

 doubled the duty and the power of the steam-engine. 

 Watt once said he had received an oblique look from 

 Trevithick, sen. The time was now come for Trevi- 

 thick, jun., to return the compliment; his improved 

 engines having made their way into the eastern mine 

 district, which Watt once looked upon as his own. 



Trevithick was short of money and on the point of 

 leaving England for South America, when Mr. Sims, 

 in the employ of Messrs. Williams and Co., favourable 

 to low pressure, was sent to negotiate for the purchase 

 of a share in Trevithick's patent of 1815 for the high- 

 pressure steam expansive pole-engine. 



" 18th October, 1816. Agreement between Trevithick and 

 Mr. William Sims, prepared by myself and Mr. Day, solicitor 

 for Mr. Sims, or for Mr. Michael Williams, under whom Sims 

 acted, recites, that in consideration of 200?. paid by Sims, he 

 was to have a moiety of the patent for Cornwall and Devon, 

 and that I should have power to act and make contracts whilst 

 Trevithick was out of England. 



" The day after contract signed, Trevithick sailed in the 



1 See Trevithick's letter, January, 181.'), vol. ii., p. 55. 



