THE CONQUEST OF NATURE 



upon his imagination for it. A print is in existence, 

 made so long ago as 1719, representing an engine 

 erected by Newcomen at Dudley Castle, Staffordshire, 

 in 1712, in which an automatic valve gear is clearly 

 shown, proving that the Newcomen engine was worked 

 automatically at this early period. That the admirable 

 story of the inventive youth, whose wits gave him 

 leisure for play, may not be altogether discredited, 

 however, it should be added that unquestionably some 

 of the early engines had a hand-moved gear, and that at 

 least one such was still working in England after the 

 middle of the nineteenth century. It seems probable, 

 then, that the very first engines were without the auto- 

 matic valve gear, and there is no inherent reason why 

 a quick-witted youth may not have been the first to 

 discover and remedy the defect. 



According to the Report of the Department of Science 

 and Arts of the South Kensington Museum: "The 

 adoption of Newcomen's engine was rapid, for, commen- 

 cing in 1711 with the engine at Wolverhampton, of 

 twenty-three inch diameter and six foot stroke, they were 

 in common use in English collieries in 1725; and Smea- 

 ton found in 1767 that, in the neighborhood of New- 

 castle alone there were fifty-seven at work, ranging in 

 size from twenty-eight inch to seventy-five inch cylinder 

 diameter, and giving collectively about twelve hundred 

 horse-power. As Newcomen obtained an evaporation 

 of nearly eight pounds of water per pound of coal, the 

 increase of boiler efficiency since his time has neces- 

 sarily been but slight, although in other requisites of 

 the steam generator great improvements are noticeable." 



[92] 



