"We are beginning another of a larger size, and I have no doubt but by making the cylindrical boiler larger, so as to take a longer tube withinside it, by which means the fire will spend itself before it leaves the tube to go up the chimney, that we shall work to much better advantage in point of fuel than we do at this present one, as this boiler is so short that a great deal of the flame of the fire goes up the chimney. We are now better acquainted with the different proportions than we at first were, for which reason I am anxious that one now making by Mr. Vivian should be made according to the directions of Mr. Trevithick.
"I beg leave to offer you the compliments of the season, and many happy returns, and
"Remain, respectfully, dear Sir,
"Your most obedient servant,
"Samuel Homfray."
Trevithick, always busy, was just now doing the work of a host, for everybody had to be taught how to make high-pressure steam-engines; and the Newcastle locomotive, the Thames steam-dredging, and other special applications of steam-power required his presence, especially the fight with Watt at Dolcoath Mine, where Andrew Vivian, as mine manager, was erecting a high-pressure steam-puffer whim-engine to compete with a Watt low-pressure steam vacuum whim-engine.
"The adventurers grumbled because Captain Trevithick was so often away from the mine. Glanville, the mine carpenter, the head man over the engines, made a trial between Trevithick's high-pressure puffer whim and Watt's low-pressure condenser. When Captain Trevithick heard of it, he wrote down from London that he would bet Glanville 50l. that his high-pressure puffer should beat Watt's low-pressure condenser. Then he came down from London and found that the piston of his engine was half an inch smaller in diameter than the cylinder. When a new piston was put in, she beat Boulton and Watt all to nothing. Persons were chosen to make a three or four weeks' trial, and when it was over, 'a little pit was found with coal buried in it, that Glanville meant to use in the Watt engine.'"[66]
Pooly, Smith, and others, say that Trevithick's Dolcoath puffer had the outer case of the boiler of cast iron, the fire-tube of wrought iron, the cylinder horizontal, and fixed in the boiler. Captain Joseph Vivian saw Trevithick's whim in Stray Park Mine about 1800 or 1801, and a similar one was erected in Dolcoath, and after a year or two a Boulton and Watt low-pressure whim was put up to beat it. The trial was in favour of the Watt engine, but everybody said the agents were told beforehand which way the report ought to go; so the engine that puffed the steam up the chimney was beaten.
Trevithick, who was busily engaged in Manchester at that time, the early part of 1805, when informed of what was going on in Cornwall, wrote:—
"I fear that engine at Dolcoath will be a bad one. I never knew anything about its being built until you wrote to me about Penberthy Crofts engine, when you mentioned it. I then requested Captain A. Vivian to inform me the particulars about it, and I find that it will not be a good job. I wish it never was begun."[67]
"Camborne, February 18th, 1806.