Page:Report from the Select Committee on Steam Carriages.pdf/57



Mr. G. Gurney. 5 August, 1831. see no other obstacle to great speed; there is no theoretical difficulty. I would wish to state, in connection with my former Evidence with respect to fuel for working slowly heavy Carriages, that my opinion was founded on some peculiar laws of momentum lately observed; it is well known that one Engine, when worked at a given rate, works expansively; that an Engine working at a quicker rate, if a piston only travels half a mile an hour, or 50 feet a minute, it will require more fuel for it to do a given work, than if working at 200 feet a minute,

Is not the momentum gained by greater velocity an accumulation of power?—I think the advantage gained by certain rapidity of action, arises from the inequalities of the road being overbalanced by the momentum of the Carriage; when the Carriage travels slowly, every inequality, every stone or slight obstacle partly destroys the momentum, but at a certain speed it overcomes them; there is no actual gain of power by momentum; it is only an accumulation very much like that in a common fly-wheel; and in a Carriage on a common road, it acts on inequalities as a fly-wheel does, in overcoming unequal obstacles in machinery.

You use coke only?—We occasionally may use charcoal, but very seldom.

What is the proportion in price and what in value between coal and coke?—I think one bushel of coals is equal in raising steam to two bushels of coke.

What is the difference of price on the average?—The difference of price is, I think, about two-thirds.

Then there would be a loss as compared together in using coke?—Coals would be much cheaper than coke, but that loss in the expence of fuel we are disposed to suffer rather than produce a nuisance on the road by smoke.

Do you conceive that there can be no mode of escaping that by any smoke-consuming apparatus?—I know of no mode that is likely to succeed, nor do I conceive that it is possible to make such a combustion of coals that is likely to consume all the sublimated or volatilized matter; the consuming of smoke