Page:Report from the Select Committee on Steam Carriages.pdf/131



Mr. Richard Trevithick. 12 August, 1831. going off that has never yet been applied, there is no need to chain the wheel; that is very easily done; if the steam is prevented escaping; the piston must stand still, and it can be let down as gently as possible; they may either stop instantly or go as easily as they please; the throttle barrel will answer the purpose to throttle between the cylinder and the discharge pipe; that would be a saving of the roads.

Have you made any observation on the injury done to the road by a Carriage propelled not in the usual manner but by a motion communicated to its wheels?—I think the roads would be less injured by Steam Carriages than by horses, because the wheels will have very little more to carry now than they have with horses, and there are no horses' feet to injure the road, therefore that part of it is saved; the Engines now will be so very light that it will be scarcely felt; the power to draw the Carriage will be very little more than the weight of harness on the horses.

Would you be inclined, for the advantage of the road, to give greater width to wheels if you give greater velocity?—I would rather give greater width; I do not think the road is injured so much, there is less friction; if a two-inch wheel goes two inches deep, and a four-inch wheel goes only one inch deep, there is two to one difference in the friction, for the ascent in getting up out of a two-inch rut requires a great deal more friction; the wider the wheels in my opinion, though the greater extent the less the friction; they use wide wheels to go over soft ground on farms to prevent their sinking; there is a great friction, for it is always going down hill and the friction is pulling it up hill; there is a power thrown away, but that would not have been the case with a wider wheel.

Do you think for a greater weight with a great velocity of carriage, you could put wheels so wide that instead of doing injury they should do good to the road?—Yes; I think if the wheels had been as wide as they ought to have been to take the advantage of ease, they would rather have done a service to the road than an injury, that is to settle down the road;