lis 



WATT AND TIIK THF.VITILICK ENGINES. 



and the late Captain Jeukin, of Treworgie, and tliey found the 

 average to be about seventeen millions." l 



One of these so-called expansive "Watt engines, erected 

 at Wheal Chance, was converted into a real expansive 

 engine by Trevithick, as described in the foregoing- 

 chapter, by his high-pressure steam-boilers and the 

 addition of his pole-engine. The conversion of the 

 other, a 63-inch low-pressure vacuum engine at Wheal 

 Gons, will be traced in this chapter. 



Mr. Taylor, who for many years took an active 

 interest in Cornish mining, says : 



" In 1798 an engine at Heiiand was found to be the best in 

 the county, and was doing twenty-seven millions, but being so 

 much above all others, some error was apprehended. This 

 engine was probably the best then ever erected, and attracted 

 therefore the particular attention of Messrs. Boulton and Watt, 

 who, on a visit to Cornwall, came to see it, and had many experi- 

 ments tried to ascertain its duty. It was under the care of 

 Mr. Murdoch, their agent in the county. 



" Captain John Davey, the manager of the mine, used to 

 state that it usually did twenty millions, and that Mr. Watt, at 

 the time h inspected it, pronounced it perfect, and that further 

 improvement could not be expected." 2 



This best engine from the hands of Watt and Murdoch 

 in the Herland Mine in 1798 may be taken as a Watt 

 stand-point, when its usual duty was twenty millions ; 

 and Trevithick and Bull erected a competing engine, 

 probably with an increased steam pressure, for Trevi- 

 thick's portable high-pressure engines were at that time 

 coming into notice ; 3 but no trace remains of the result 

 of this contest of the Watt and the Bull engine, though 

 it was one of the causes of the lawsuits. 



1 Lean's ' Historical Statement of 

 Steam-Engines in Cornwall,' p. 7. 



2 'llecords of Mining,' by John 



Taylor, F.H.S., &c., part i., p. 155; 

 published 1829. 

 3 See vol. i., p. <if>. 



