How great was the practical insight his genius gave him, and how imperfectly his followers have acted on this advice given sixty years ago!
The chimney that at its top would ignite paper, threw to waste four and a half times more heated air than was requisite to supply the quantity of heat which passed through the working cylinder in steam, and at a temperature nearly four times greater than the temperature of the steam. It needs only to observe the burnt appearance of a steamboat funnel of the present day to know how wasteful we still are, or how very ignorant of improved methods of economizing fuel.
To prevent this waste of heat up the chimney be proposed to do away with the chimney altogether; the fire-place was to be a close one, having a blast under the fire-bars of a strength sufficient to force the air, heated by its passage through the fire, direct through a small valve into the water in the boiler, by which means all the heat given by ignition would pass into the steam, and his steam-puffer become an aërated steam-engine.
From the following it appears that this plan of Trevithick's is now coming into use as something quite new:—
"In your last impression, under the head of 'Air and Steam combined, as a Motive Power,' you state 'the invention was described to be that of Mr. Warsop, but we have recently heard that a few years back (1865) the same invention had been protected in an earlier patent than Mr. Warsop's, by Mr. Bell Galloway.'"[3]
Trevithick thought of patenting a plan for reducing copper ore by the use of a blast, in preference to the usual air-furnace and chimney, but something similar had been tried by Mr. Gould, and he therefore proposed to erect a blast-furnace in Dolcoath Mine, receiving a portion of the saving of fuel as his remuneration. Such a furnace worked there for many years, until copper smelting was removed from Cornwall to Wales. The plans for a breakwater at St. Ives were for an undertaking that has since been in many hands, but without success, except perhaps for the convenient making of members of Parliament. Some slight progress has been made by engineers and contractors, but vessels are not willingly taken to the port, and ratepayers grumble at unprofitable harbour taxes.
"Dear Trevithick,
"London, January 20th, 1811.
"I have not lost any time in mentioning your wishes respecting a compensation for the plan of smelting copper to Lord Dedunstanville, who intends mentioning the affair in his next letter to Mr. Reynolds. Lord Dedunstanville wishes you extremely well, but it is impossible for him to settle anything apart from the adventurers.
"I am very sorry that anyone should have executed the plan of reducing copper ore by a blast-furnace before you had put into practice the idea suggested to me ten years ago. It ascertains, however, that the contrivance will succeed, although you are certainly reduced to ask moderate terms, and I know not what can be more moderate than those you have asked, except that I would recommend some limit as to time.