100 Mr. W. J. Henwood's Notes on some recent Improvements 



still at work. Mr. Farey continues *, " In a short time after 

 Mr. Woolf's patent expired, most of the old Boulton and 

 Watt's engines in Cornwall were altered to work by high- 

 pressure sleam on his system : some few had an extra cylinder 

 added." Instead of the pressure of steam in general use being 

 raised at that period, I assert no such alteration took place 

 in a more marked degree, then, than had before obtained ; 

 and the alteration which at all took place was not in conse- 

 quence of Mr. Woolf's assertions or performances, but of those 

 of Capt.Trevithick. Will Mr. Farey name an engine to which 

 a cylinder was added (that it might be worked on what he calls 

 Mr. Woolf's system) after the expiration of that patent? He 

 proceeds^, " The advantage of the change from low-pressure 

 to high-pressure steam, on Mr. Woolf's system, was manifest 

 in all cases ; but it was greater or less, according as the steam 

 was used stronger and with more or less expansive action." 

 Now, I maintain that there is not a shadow of ground for this 

 assertion, and I challenge Mr. Farey to prove its accuracy. 

 He says :j;, " Previous to 1 S26 the steam cases were not clothed, 

 but exposed to the air." That the steam cases of Boulton 

 and Watt's engines were covered with lath and plaster whited 

 on the outside, is notorious ; their steam pipes Avere also 

 encircled with straw ropes plastered and whited. The steam 

 case at Dolcoath engine was surrounded with a casing of sheet- 

 iron ; the interval of about four inches being filled with straw, 

 hemp, saw-dust, and other imperfect conductors of heat. 

 Mr. Farey says §, " Mr. Hornblower, who practised that sy- 

 stem" (expansive working) " in two cylinders, did not suc- 

 ceed so well as Mr. Watt himself, who only used one cylin- 

 der." I repeat, that " variation of the elasticity of steam em- 

 ployed by no means affects the principle of the invention ;" 

 the superiority of one cylinder over two being proved with 

 low-pressure steam, it appears to me " ignorance in spite of 

 experience" to expect a contradictory result by variation of 

 tension only; and, still stumbling over the results of his own 

 experiments as well as those of Messrs. Watt and Horn- 

 blower, Mr. Woolf's engine with two cylinders at Huel Al- 

 fred was a signal failure. 



The improvements which came prominently into notice in 

 1827 were commenced by Capt. Grose, at Huel Hope mine 

 inGwinear parish, in 1825. They do not in any part consist, 

 as Mr. Farey states ||, in " using better boilers ;" for they are 



• Phil. Mag. and Annals, N.S. vol. viii. p. 312. t Ibid. 



X Ibid. p. 312-313. ^ Ibid. p. 312. note. || Ibid. 313. 



precisely 



