"The steam-whim that is now turned idle at the Valley was 13-1/2-inch cylinder, 4-feet stroke; it turned the whim one revolution to one stroke, and lifted the kibbal the same height at a stroke as my engine did, and I think took the same number of gallons of steam to lift a kibbal as mine did. Their steam was not above 4 lbs. to the inch; _mine was near 40 lbs. to the inch_; yet I raised my steam of near 40 lbs. with a third of the coals by which they got theirs of 4 lbs. to the inch. This is what I cannot account for, unless it is by getting the fire very small and extremely hot. Another advantage I have is, that there is no smoke that goes off from my fire to clog the fire sides of the boiler, while the common boilers get soot half an inch thick, and the mud falls on the bottom of the boiler, where the fire ought to act; but in these new boilers the mud falls to the bottom, where there is no fire, and both the inside and outside of the tube are clean and exposed both to fire and water. This fire-*place[**hyphenated below] of 14 inches was 5 feet long when I came down, and then the coal did not do above one-seventh of the duty that it now does.

"I would be very much obliged to you for your opinion on what I have stated, and what _advantage you think the great engine is likely to get from working with steam about 25 lbs. to the inch, and shut off early in the stroke, so as to have the steam about 4 lbs. to the inch when the piston is at the bottom. I think this, with the advantage of the fire-place, will make a great saving._

Life of Richard Trevithick, Volume II (of 2) — Part 105

"The present fire-place is 22 feet from fire-door to fire-door, 9 feet wide, and 7 feet thick in fire. There is not one-tenth of the coals that are in the fire-place on fire at the same time; it will hold 30 tons of coals at one time, and I think that a great deal of coal is destroyed by a partial heat before it takes fire. A boiler on the new plan will not cost more than two-thirds of the old way, and will last double the time, and can be cleaned in three hours. It requires twenty-four hours in the old way, and we need to clean the boilers only one-fourth the number of times.

Life of Richard Trevithick, Volume II (of 2) — Part 105

"Though these trials have shown so fairly that it is a great advantage, my old acquaintances are still striving with all their might to destroy the use of it; but facts will soon silence them.

Life of Richard Trevithick, Volume II (of 2) — Part 105