The result of the experiments made on the Rocket was as follows: The engine was taken to the extremity of the stage, the boiler being quite cold. The fire-box was then filled with coke, and the fire lighted. The time was observed which it took to raise the safety valve at a pressure of 50 lbs. on the square inch, which was 57 minutes. When the steam was at this pressure, which was at 10° 36′ 5′′ o'clock, the engine started from the west extremity of the stage, and arrived at the same place, after performing ten trips, or 35 miles, including the one eighth at each end for starting and stopping, at 1° 48′ 38′′ o'clock. The total time occupied was 3° 11' 48"; and the time taken in going 30 miles at full speed was 2° 14′ 8′′, being equal to 13 miles per hour. In the second experiment the total time occupied was 2° 57′ 9′′, and the time in going 30 miles at full speed 2° 6′ 9′′, being equal to 14 miles per hour. The maximum velocity was above 19 miles in the first journey and 20 miles in the second journey, and the minimum velocity in the first journey was 11 and in the second 13 miles. The greatest rate of motion attained was in the last eastward trip of 1 miles, which was performed in 3′ 44′′, being at the rate of 29 miles per hour.

The eastward trip is

to be taken as the per

formance of the engine, as, in going east, the engine dragged the carriages after it, whilst, in going west, it pushed them before it; the former were invariably performed in less time. Taking the eastward trips, the average speed, conveying 17 tons, was 15 miles an hour.

The quantity of coke consumed in the two experiments was 1085 lbs., which, for 70 miles, including the engine and tender, is 0.91 lb. ; exclusive of ditto, 1.63 lb. per ton per mile. The quantity of water used was 579 gallons, or 92.6 cubic feet.

For each cubic foot evaporated, the fuel consumed was 11 lbs. of coke, and the evaporating power of the engine, per hour, was about 18.24 cubic feet of steam.

EXPERIMENTS WITH THE SANS PAREIL ENGINE.

The Sans Pareil of Mr. Hackworth was the next engine experimented with. This engine was not unlike Trevithick's. It had two cylinders of seven inches in diameter with eighteen inches' length of stroke. One vertical cylinder was placed on each side of the boiler, and directly under them one pair of the carriage wheels; both the

pistons of the cylinders worked the same axle. The two pairs of wheels were coupled together by connecting rods in order that the adhesion of the whole might be taken advantage of; plan which has since been advantageously made use of.

a

Fig. 55. represents the side elevation of the Sans Pareil, and fig. 56. the ground plan of the boiler.

The principle of raising the steam was the same as that of the Rocket, namely, by the chimney acting as an exhausting power in keeping up the combustion of the fuel, and the steam from the cylinders being ejected into the chimney. The boiler was of a cylindrical form, about four feet two inches in diameter, and six feet long, having one flat and one round end. The steam was generated in the double tube bb, which passed from one end of the boiler (A) to the other, returning to the fire grate, which was placed at the same end as the chimney c. The tube bb projected about three feet from the end of the boiler, having a casing surrounding the tube for increasing the area of heating surface, and to admit a sufficiency of air to pass through the fire-grate. The tube was two feet diameter at the fire, decreasing to

fifteen inches in diameter at the chimney. The grate-bars were five feet in length, and the area of surface radiating caloric or that surface exposed to the direct action of the fire was 157 square feet, and the area in contact with heated air or communicative heat was 74.6 square feet, the area of the fire-grate was 10 square feet: the two former were much less than those of the Rocket, and the last larger.

Tons cwt. qrs. lbs.

The weight of the Sans Pareil was, with water, 4 15 2 0 Tender, with water and fuel,

Three carriages, with stones

3 630

This engine was tried in a similar manner to the preceding; but the last experiment was not completed from the derangement of the enginepump: but, so far as the trial was made, the result was inferior to the Rocket.

At full speed ten miles were performed in 50'49", which was equal to 12 miles per hour.

The maximum velocity in one trip was 161 miles per hour, and the minimum was 12 ditto.

The greatest velocity attained was in the fifth trip, when 11⁄2 mile was traversed in 3' 59", being at the rate of 224 miles per hour-whereas the

S