174 THE WATT AND THE TREVITHICK ENGINES. 



4-feet stroke, 15 strokes per minute, or a duty equal thereto ; for 

 which they will pay you 50 guineas one month after the engine 

 shall be at work, and 50 guineas more at four months after that, 

 and 50 guineas more at four months from that time, making the 

 full payment of 150 guineas in nine months from the time the 

 engine shall set at work, the adventurers paying all expense, 

 except the engine materials, which shall be delivered on the 

 mine. But in case the engine not performing the above duty, 

 the adventurers to be at liberty to return the same engine, and 

 you to pay back all the money that you had received for the 



said engine. 



" Signed by GABL. BLEWETT, 



" in. behalf of the Adventurers and Company." 



Trevithick was willing to spend more than his last 

 penny in establishing the superiority of his high-pres- 

 sure steam expansive engines, but the selfishness of 

 adventurers retarded their progress. The atmospheric, 

 mentioned by Watt as working in Dolcoath in 1777, 1 did 

 five or six millions of duty, yet in Trevithick's hands, 

 about 1798 to 1800, when he erected his globular boiler 

 with internal tube, one of them was tested with the 

 63-inch Watt low-pressure vacuum engine, when the 

 latter did sixteen millions to ten millions by the atmo- 

 spheric engine, being nearly double the duty it per- 

 formed in its original form ; and we shall still trace 

 this same engine as Bonze or Gons until it increased to 

 six times its first duty under the name of Stray Park 

 63-inch. 



Trevithick having erected a high-pressure steam con- 

 densing whim-engine at Cook's Kitchen, 2 and in Dolcoath 2 

 a high-pressure puffer whim-engine, pleaded hard in 

 1806 3 to be allowed to supply the large pumping engines 

 of Newcomen and Watt with higher pressure steam from 



1 See vol. i., pp. 30, 57 ; vol. ii., p. 115. 2 See vol. i., p. 91. 



3 See vol. ii., p. 142. 



