18 
THE CORNISH PUMPING ENGINE. 
roasting ore, to the purpose of evaporation; an arrangement of the latter descrip 
tion having been put in practice at Camborne. 31 
But it is singular that all these attempts at improvement were directed to the 
boiler alone; no one seems to have thought of improving the engine. They were 
all failures, and we may safely affirm that the atmospheric engine was very nearly as 
perfect after Beighton adapted the hand gearing to it in 1718 or 1720, as it ever 
became until the improvements of Smeaton half a century afterwards. 
25. The great expense of fuel was still a heavy tax upon the use of the engine, 
for every one of magnitude consumed £3000 worth of coal per annum; 32 and as 
the mines were worked lower, and more power became requisite, the expense was 
frequently so great as to balance the profits of many mines. 
If therefore new improvements had not arisen, the use of the engine must soon 
have been limited to those works whose produce was so rich, or profits so great, 
as to enable them to bear this heavy expense of drainage. 
26. The illustrious John Smeaton, who could scarcely take any subject in hand 
without improving it, was the first who attempted to better the condition of the 
engine itself. He does not seem to have added any thing new to the machine, or 
to have invented any thing connected with it which can easily be particularized; but 
by a careful study of its action, and an accurate theoretical consideration of the 
several relations of its parts one to the other, he so contrived to improve their pro 
portions as to increase the duty by this means alone nearly fifty per cent. 
Smeaton first turned his attention to the fire engine about 1767, and in a few 
years afterwards constructed many large engines on his improved scale; one of 
which, erected at Long Benton colliery, near Newcastle, in 1772, with a cylinder 
53 inches diameter, was what he termed his standard engine. 
27. In 1775, Mr. Smeaton erected an atmospheric engine with all his improve 
ments at Chacewater mine, near Truro. This was the most powerful engine then 
in existence, and probably the largest he ever made. 
The cylinder was 72 inches diameter, and the stroke of the piston was 9 or 9^- 
feet. The water load was equal to 7f lbs. per square inch of the piston, and the lift 
was 51 fathoms (306 feet). 
It had, when originally erected, one boiler 15 feet diameter placed immediately 
31 See Nicholson’s Journal, vol. viii. page 169, for a description of this boiler, by J. C. Hornblower. 
It was a stone one, with copper tubes running through it from end to end. Vide also Farey, p. 236 ; and 
Pryce’s Mineralogia Cornubiensis. 
32 Mineralogia Cornubiensis, p. 308.