LIVERPOOL EXPERIMENTS.

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nication between two of the most important towns in the kingdom, we cannot but express our decided conviction, that a system which necessarily involves, by a single accident, the stoppages of the whole, is totally unfitted for a public railway." To the same effect is the following opinion of Mr. Walker:- ." The probability of accident, upon any particular part of the system, is, I think, less with the stationary, than with the locomotive; but, in the former, the effects of an accident extend to the whole line, whereas, in the latter, they are confined to the particular engine and its train, unless they happen to obstruct the way, and prevent others from passing. The one system is like a number of short unconnected chains; the other resembles a chain extending from Liverpool to Manchester, the failure of one link of which would derange the whole.”

RECENT LOCOMOTIVE ENGINES.

111. Liverpool Experiments.-The nature of the moving power having been decided in favour of the locomotive engine, a premium of £500 was offered, in April, 1829, by the directors of the Liverpool and Manchester Railway, for the best locomotive engine, subject to certain stipulations and conditions. The principal of these were, that the engine must "effectually consume its own smoke;" that the weight of the machine, with its complement of water in the boiler, must, at most, not exceed six tons; that the load, attached to the engine, must be three times the weight of the engine; that the engine and boiler must be supported on springs, and rest on six wheels, if their weight amounted to six tons; that a machine of less weight would be preferred, if capable of drawing after it a proportionate weight, and that such a machine, if reduced to a weight of four tons and a half, or under, might be placed on four wheels; that the pressure of steam in the boiler was not to exceed 50lbs. per square inch; and that the price of the engine, which

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might be accepted, was not to exceed £550, delivered on the railway. The day fixed for the trial was the 6th of October following; the place appointed for the trial was a level piece of road, of a mile and three quarters in length, at Rainhill. The distance to be performed was 70 miles, or twenty trips forward and backward. The engine was to accomplish this in two journeys of ten trips, or 35 miles each, which would be equal to the travelling from Liverpool to Manchester, and back again; between the trips, the engine was to be supplied with fresh fuel and water. The average rate of travelling was not to be less than ten miles per hour. The following engines were competitors for the prize:

Of these engines, the "Cyclopede" was a horse-machine; it was therefore not qualified to compete for the prize; its performance was only six miles per hour. The "Perseverance" was, after a short trial, withdrawn by its owner, as being unsuited for the purposes of the Company. Three competitors only remained; the construction and performance of the rival engines are described in the following paragraphs.*

112. Stephenson's "Rocket" Engine.-The "Rocket" Engine of Mr. Robert Stephenson, the engineer of the London and Birmingham Railway, was first put upon trial. The

* The reader who may be interested in the "Liverpool Experiments," will find them described, with minute details and tabular arrangements, in the valuable work of Wood on Railroads, 3d edit. 1838.

STEPHENSON'S "ROCKET" ENGINE.

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weight of the engine, with the tender and the load, was as

This engine performed the first trip of 35 miles in 3 hours 11 minutes and 48 seconds, being at the rate of upwards of 11 miles an hour; and, after taking in a fresh supply of water and coke, it performed the second half of its task in 2 hours 57 minutes and 9 seconds, being at the rate of upwards of twelve miles an hour; this speed included the stoppages at the two ends of the trial ground. Had the 70 miles been performed in a continued line, the performance would be estimated at 17 tons, including the engine, in about five hours, or at the average rate of 14 miles per

hour;

Fig. 63.

the water evaporated, 114 gallons per hour; the consumption of coke, 217 lbs. per hour. The general appear

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66

STEPHENSON'S ROCKET" ENGINE.

ance of the "Rocket" engine is illustrated in the preceding figure. It will be seen to differ in several particulars from the engines already described, particularly in the mode of generating the steam. A represents a cylindrical boiler with flat ends, six feet in length, and three feet four inches in diameter. To one end of the boiler is fixed a box, or furnace B, at the bottom of which are the bars of the grate; the box consists of a double case, having a space of about three inches between the two casings; this space is kept constantly filled with water. The boiler and furnace box are represented in profile in fig. 63, and in a transverse section, in fig. 64; the letters correspond with the same parts in both figures. A pipe C communicates from the lower part of the furnace case with the boiler, and supplies the latter with hot water; at the top of the case, a pipe D conveys the steam to the boiler. The upper half of the boiler is devoted to steam, the lower half is kept constantly supplied with water. The lower

B

Fig. 64.

half of the boiler is traversed by 25 copper tubes, each of three inches in diameter, opening into the furnace-box at one extremity, and into the chimney at the other; these act as flues to convey the heat of the fire to the water in the boiler. The cylinders, one only of which is shown in the figure, were placed one on each side of the boiler; their action was confined to one pair of wheels, as represented above. The generation of the steam is effectually aided by the draught of the chimney; and this is materially increased by the escape of the steam into it from the cylinders by the pipes L, one of which is seen in the figure, the other being on the opposite side of the engine.

113. Hackworth's "Sans Pareil" Engine.-The next engine put upon trial was Mr. Hackworth's "Sans Pareil."

66
HACKWORTH'S SANS PAREIL" ENGINE.

155

The weight of this machine, with its tender and load, was as follows:

This engine, being above the stipulated weight for four wheels, was merely put upon trial, the results of which were to be made the subject of a further consideration. During the journey, the pump which supplies the boiler got out of order, and the experiment ended. The average performance of this engine was eleven tons, exclusive of the engine and tender, drawn at the rate of about fifteen miles per hour; the water evaporated, was nearly 150 gallons per hour; the coke consumed, 692 lbs. per hour. The general character of the "Sans Pareil" engine is given in the following figure.

Fig. 65.

The boiler is cylindrical, and six feet in length, having one end flat, the other convex. The cylinders are placed verti