xl 
and of their performance the details are few. It seems, however, 
that they were rarely loaded more than eight pounds on the inch,* 
—that the pressure of steam in the boiler seldom exceeded one 
pound above the atmosphere,}|—that,—although some were worked 
fifteen or sixteen {—the two best averaged about six strokes per 
minute,§—and that the duty of these, during August and Sep- 
tember 1778, averaged (7,037,800 Ibs. lifted one foot by—84 lbs. 
—a bushel) 9,383, 7133 per hundred weight (112 Ibs.) of coal.§ 
In this experiment 14,080 bushels of coal were expended ; in 
1792, however, the same mine (Poldice) was drained thirty-two 
fathoms deeper by one of Boulton and Watt’s engines, which 
consumed in a corresponding period 8,824 bushels only, and per- 
formed a'duty of 26,708,515 per (84 Ibs. bushel, or 35,611,540 
per cwt.|| 
The first of Boulton and Watt’s engines erected in Cornwall 
was on the Chacewater mine in 1777;% three others were in 
course of erection during 1778 ;** fourteen were at work in 1780 ;tF 
twenty-one had been already set up in 1782, when one of New- 
Borlase, Nat: Hist: pp.173-175. Pryce, Mineral: Cornub: p. 154. Farey, 
Steam Engine, p 190. Gilbert, Phil: Trans: exx., p. 122. Redding, Yes- 
terday and To-day, i., pp. 128-136. 
“Thirty-six years ago, this county had only one fire engine in it; since 
which time above three score have been erected. 
Pryce, Mineral: Cornub: (1778), xiv 
« Ibid, pp. 155, 159. 
+ Borlase, Natural History, p.172. Pryce, Mineral: Cornub: p. 156. 
Farey, Steam-Hngine, p. 202. 
+ Borlase, Natural History, p. 173. Pryce, Mineral: Cornub: pp. 
155, “159. 
§ Wilson, Comparative Statement, p. 8. Gilbert, Phil: Trans: cxx., 
. 124. 
: It is remarkable that Messrs. Watt, Boulton, Tremayne, Williams, 
Williams, and Brown, the Reporters, mention neither the force of steam 
employed, nor even the dimensions of the engines. 
|| Wilson. A comparative statement of the effects of Messrs. Boulton and 
Watt's Steam-Engines with Newcommen’s and Mr. Hornblower’s (Truro, 
1792), p. 8. 
q Pryce, Mineral: Cornub: p. 318. Smiles, Lives of Boulton and 
Watt, pp. 230, 235. 
There still existed, in my youth, a tradition of the clamour which arose 
when—from inaccuracy of balance—the engine stopped on completing its 
first (indoor) down-stroke ; the, scarcely evitable, defect, was, however, recti- 
fied in a few minutes. 
** “At Ting- Tang, Owanvean, and Tregurtha Downs,” Pryce, Mineral ; 
Cornub : p. 313. Smiles, Lives of Boulton and Watt, pp. 224, 230, 242, 244. 
++ Smiles, Lives of Boulton and Watt, p. 275. 
