138 THE WATT AND THE TREVITHICK ENGINES. 



does, can speak with confidence. Its 18 inches diameter steam- 

 cylinder consumes as near as can be 3 tons of coal in twenty- 

 four hours, or 18 tons per week ; and in this time it rolls with 

 ease 130 tons long weight of iron from the puddling furnaces, 

 at the same heat, into bars of 3 inches by about half an inch 

 thick. Now, one on Messrs. Boulton and Watt's plan, of * 24 

 inches ' steam-cylinder, at our neighbouring works at Dowlais, 

 employed in doing exactly the same kind of work, consumes 

 full as much coal, and rolls only 90 tons in the week. These 

 being facts, open for any person daily to see, must convince any 

 dispassionate man of the superiority of ' Trevitbick's engines/ 

 and that the saving of fuel is nearly one-third, besides the other 

 advantages of saving water and grease, which is no little. The 

 packing of the piston now gives us little or no trouble, it goes 

 from a fortnight to a month, opening the top now and then to 

 screw it down, as it gets slack, which should be attended to. 

 We use no grease or oil in packing the piston or working the 

 engine, having found blacklead mixed with water, and poured 

 'a little now and then' through a hole on the top into the 

 steam-cylinder, suits the packing of the piston much better, and 

 is cheaper than anything else. About Is. worth of black- 

 lead will last our engine a week. We are now so thoroughly 

 convinced of the superiority of these engines that I have just 

 begun another of larger size. The boiler is to be 24 or 26 feet 

 long, 7 feet diameter, fire-tube at wide end 4 feet 4 inches, 

 and at narrow end, where it takes the chimney, 21 inches, 

 steam-cylinder 23 inches diameter. This boiler, on account of 

 the length of its tube withinside, will, I have no doubt, get 

 steam in proportion, and work the engine with much less coals 

 than our present one. Trevithick is at Coalbrookdale, Man- 

 chester, &c., &c., very busy, a great number of engines being in 

 hand in that part of the world ; and I think by perseverance 

 the prejudice is wearing away very fast, and in spite of all 

 Messrs. Boulton and Watt's opposition, they must and will take 

 the lead of theirs. Any person now wanting engines, must be 

 next kin to an idiot to erect one of Boulton 's in preference to 

 Trevithick's. I find there is a small one making near you by 

 Mr. Vivian. I hope they have corresponded with Trevithick 



