xlix 
the Engine Reports;* but the others scarcely surpassed ordinary 
single-acting engines, made at the same time. Hornblower’s com- 
bined-cylinders were last worked in Cornwall by Woolf, at Wheal 
Alfred, about 1824;+ but their performance was surpassed by 
that of an ordinary single-engine on the same mine.t The en- 
gines at Wheal Abraham, Wheal Vor, and Wheal Unity, were 
supplied with the tubular cast-iron boilers, for which Woolf had 
taken out a patent ;§ but—from unequal expansion—both their 
joints and tubes were so frequently broken, that they were advan- 
tageously replaced by the cylindrical boilers of Trevithick.|| We 
owe to Woolf’s experience in London the high finish, and the 
careful working,{] of our engines; but whether their proportions 
have been improved since Watt’s time may, possibly, be ques- 
tioned. 
Before Trevithick left England for Peru,** in 1816, he either 
sold}} his patent (non-condensing) high-pressure engine or granted 
a licence for using it ; and Sims{t—whose practice exceeded that 
of any other engineer in Cornwall—forthwith unitea it with the 
ordinary single (condensing) engine, admitting steam from the 
boiler beneath the pole of the former, and thence expanding it 
above the piston—in the larger and longer cylinder—of the 
* Lean, pp. 31, 32. Taylor, Records of Mining, 1., pp. 156, 157. Quar- 
terly Mining Review, ii., pp. 41, 42. Annales des Mines, 3me Série, ii., pp. 
59, 60. 
+ Henwood, Hdin: Journal of Science, x., p. 37. Farey, Phil: Mag: 
and Annals, viii., p. 312. 
This engine is figured in the Engineer, (6th May, 1870), xxx., p. 277; 
(8rd March, 1871), xxxi., p. 139. 
+ Farey, Phil: Mag: and Annals, viii., p. 312. Henwood, Ibid, x., 
p. 100. Lean, Historical Statement, pp. 63, 64. Husband, Proceedings of 
the Institution of Civil Engineers, xxiil., p. 77. 
Notwithstanding Mr. Taylor was principal agent of Wheal Alfred at the 
time, his memoir, on the Duty of Steam-Engines (Records of Mining, i., 
pp. 149-165) makes no mention of this circumstance. 
§ Gregory, Mechanics, ii., p. 403. Rees, Cyclopedia, xxxiv., (N.), Pl. 
v., Figg. 4,5. Phillips and Darlington, Records of Mining and Metallurgy, 
p. 87. The Engineer, (6th May, 1870), xxx., p. 277. 
|| Henwood, Hdin: Journal of Science, x., p. 36. Pole, Cornish Pump- 
ing Engine, p. 61. 
q Henwood, Hdin: Journal of Science, x., p. 36. Pole, Cornish Pump- 
ing Engine, p. 56. 
** Boase, Cornwall Geol: Trans: i., p. 217, 
++ Pole, Cornish Pumping Engine, p. 58. 
++ William Sims was born at or near Chacewater on the 29th of De- 
cember, 1762, and died at Whitehall, in Kenwyn, on the 16th of October, 
1834. 
To the courtesy of this intelligent and excellent gentleman, I owe much 
information, which it might now be impossible to obtain, regarding the 
early application of steam-power in Cornwall. 
D 
