Page:Report from the Select Committee on Steam Carriages.pdf/134



Mr. Richard Trevithick. 12 August, 1831. a rut there is a very great difficulty in the wheel getting out of that rut, for there is no footing; but where it does not sink, that is not the case.

Supposing the width of the wheel to be the same on a Carriage and Steam Engine, and the weight of the Carriage the same, do you consider that a wheel perfectly cylindrical, with a horizontal axle, preferable to a wheel dished like that of a common stage coach, with a common axle?—You cannot have a dished wheel to a great width, without its dragging as I have described, unless you alter the system. If you keep the present dish, you must have a narrow wheel, or it is rubbing; but if it is a straight axle, it ought to be as wide as that where there is no more friction, and then the wide wheel will not do half the mischief that the coach-wheel does. The present stage coach-wheel will do a great deal more mischief, working as it does, than if it had been perpendicular.

Are you to be understood that in no state of the road a wide wheel such as you have described would do injury to the road?—A wide wheel will do a partial injury, but not one quarter of that which it would do if it were narrow.

What sort of injury will it do?—It will tend to crush the pebbles and wear them, but that will be very trifling indeed; if you have a hundred weight upon a wheel of an inch wide, and a hundred weight upon a wheel of two inches wide, that one of an inch wide will break ten times as many pebbles as the other; every inch it goes will break stones; a wide wheel does away the injury.

You are aware that in the carriages that run at present on the common roads the wheels do not run in the same track, in the event of having wheels with the tires four inches wide, do you think it would be better that the tire of the hind wheels should run in the same track or a different track?—For the Carriage making one turn only, it is easier for the wheels to go on the same track; but if you wish to take the average of the duty, they never ought to go in one track.

You think in the Steam Carriages that the tire of