Page:Report from the Select Committee on Steam Carriages.pdf/143



Mr. Richard Trevithick. 17 August, 1831. scale, and wide surfaces will bed snow, and form a firm road, while narrow surfaces would defeat the effect. Another proof of wide surfaces bedding firmly, is seen in Cornwall, where the mills for stamping the ores in the mines have Steam Engines in constant work, lifting twelve inches high iron stampers of three or four hundred weight, of about seventy inches of bearing; at the bottom surface these form their own, bed, which is about a foot thick of Macadamized stones, and are an everlasting foundation, though the stamps pulverize at the surface as fine as sand. It would be advisable for the fore and hind wheels of Carriages to run about half the track out of a line from each other, because the bank that is formed by the fore wheel would be rebedded by the hind one, and the leveller the road is kept, the less the jolts, and of course the shoaler will be the ruts, while the surface of the road remains sound, and even the wear is scarcely any thing, and the crushing cannot take; place but in a very small degree; because the small gravel binding uniformly with the larger stones, supported on every side, brings the whole surface into uniform contact with the wheel, in which state but very little injury can be done; but when uneven or broken, the loose stones roll about without a support, and kept: so by narrow wheels, they independently receive the whole weight of the wheel, and instead of being bedded down are crushed to powder. The unnecessary, resistance given to Carriages and wear of roads by narrow wheels far exceeds all conception. As a proof that locomotive wheels will not injure the roads by slipping round. I give you the copy of a Report printed on the performance of the locomotive Engines on the Manchester Road for the premium. The following calculation, founded on the reported result, was made by Mr. Vignoles and Mr. Price, of Neath Abbey.—The maximum number of strokes was 142 per minute, while 440 yards were traversed in 43 seconds, diameters of wheels 50.1 inches, circumference 157.4 inches; 157.4×142 inches, equal to 621 yards, being, the velocity per minute of the circumference of the wheel, or 21 miles and 300 yards per hour; then as