WHEN the construction of that great work, the Liverpool and Manchester Railroad, was commenced, and even after it had been in progress for several years, its directors had not determined the motive power to be employed upon it. Horse-power had the strongest advocates. Another method, and one having a number of advocates, was that of stationary engines to draw the trains along. By this method the line of road over which the transport is conducted is divided into a number of short sections, at the extremity of each of which an engine is placed. The wagons or carriages, when drawn by any one of these engines to its own station, are detached and connected with the extremity of the chain worked by the next stationary engine, and thus the journey is performed station to station by separate engines. It was proposed to divide the Liverpool and Manchester road into nineteen stations, or sections of about a mile and a half each, with twenty-one engines fused at the different points to work the chains forward. Not a single professional man of any eminence could be found who preferred the locomotive over the fixed-engine power as above, George Stephenson only excepted. He stuck to the locomotive-power; and finally committees were appointed at his suggestion to witness the performance of his locomotives employed in hauling coal upon the Stockton and Darlington Railroad. The report from the chairman of one of these committees states that, "although it would be practicable to go at any speed that the size of the wheel and the number of strokes in the engine might allow, yet it would not be safe to go at a greater rate than nine or ten miles an hour." This was considered a very high rate of speed in those days. The completion of the road was fast drawing nigh. The great tunnel at Liverpool was finished; a firm road over Chat-Moss was completed; and yet the directors had not settled in their minds what power was to be used upon the road. Prejudice still existed against the use of locomotives. The road had been constructed throughout its entire length in a most substantial manner, and cost upward of £20,000 per mile, amounting to £820,000. The rails used were made of forged iron, in lengths of fifteen feet each, and weighed 170 lbs. each. At the distance of every three feet the rail rests on blocks of stone, set into the ground and containing about four cubic feet each. Into each block, two holes, six inches deep and one inch in diameters are drilled; into these are driven oak plugs, and the cast iron chairs into which the rails are fitted are spiked down to the plugs, forming a structure of great solidity, and in every respect calculated for any power that might be determined upon by the Board.

Finally, in the spring of 1829, the directors appointed Messrs. Stephenson and Lock, and Messrs. Walker and Rastrick, experienced engineers, to visit the different railways where practical information respecting the comparative effects of stationary and locomotive engines could be obtained; and from these gentlemen they received reports on the relative merits of the two methods, according to their judgment. The result of the comparison of the two systems was, that the capital necessary to be advanced to establish a line of stationary engines was considered greater than that which was necessary to construct an equal power in locomotives; that the annual expense for maintaining the stationary engines was likewise greater than for the locomotives, and consequently the expense of transportation by a stationary system was greater in like proportion. The system of locomotive-power, therefore, was entitled to the preference. Yet another consideration influenced the directors in its favor, which was this: Should an accident occur on any part of the railroad worked by stationary engines, a suspension of work along the entire road would be involved in the consequences; accidents arising from the fracture of any of the chairs, or from any derangement in the working of any of the fixed engines, would effectually stop the intercourse alone the entire line; while in the use of locomotive-power an accident could only affect the particular train of carriages drawn by the engine to which the mishap might occur. "The one systems says Mr. Walker, in his report, " is like a chain extending from Liverpool to Manchester, the failure of a single link of which would destroy the whole; while the other (the locomotive system) is like a number of short and unconnected chains, the destruction of any one of which does not interfere with the effect of the others, and the loss of which may be supplied by others with facility." However, to determine the matter, a prize was offered by the directors of £500 for a locomotive which should be produced by a certain day, and perform a certain duty, as follows:

1. The engine must effectually consume its own smoke.

2. The engine, if of six tons' weight, must be able to draw after it, day by day, twenty tons' weight, including the tender and water-tank, at ten miles an hour, with a pressure of steam upon the boiler not exceeding fifty pounds to the square inch.

3. The boiler must have two safety-valves, neither of which must be fastened down and one of them completely out of the control of the engineer.

4. The engine and boiler must be supported upon springs and rest on six wheels, the height of the whole not exceeding fifteen feet to the top of the chimney.

5. The engine with water must not weigh more than six tons, but an engine of less weight would be preferred, although drawing a proportionally less load behind it; if of only four and one-half tons, it might be put on four wheels.

6. A mercurial gauge must be affixed to the machine, showing the steam-pressure about forty-five pounds to the square inch.

7. The engine must be delivered, complete and ready for trial, at the Liverpool end of the railway, not later than October 1, 1829.

8. The price of the engine not to exceed £550.

The project and the conditions were thought to be preposterous. An eminent gentleman of Liverpool, afterward inspector of steam-packets, said that "only a parcel of charlatans would have issued such a set of conditions;" that it had been "proved to be impossible to make a locomotive-engine to go ten miles an hour; but, if it was ever done, he would undertake to eat a stewed engine-wheel for his breakfast!"

The Stephenson locomotive factory was still in operation at Newcastle, but for a long time it did not pay expenses. Mr. Stephenson now set about the construction of his far-famed engine the Rocket, to contend for the prize just offered by the Liverpool and Manchester railroad directors. As the name of Mr. Stephenson's Rocket is familiar in the mind of every railroad engineer and machinist of the present day, we will describe it, for the information of all who feel interested in the subject: The boiler of this new engine was cylindrical in form, with fat ends; it was six feet in length and three feet in diameter, the upper half of the boiler used as a reservoir for the steam, the lower half being filled with water; through this lower part twenty-five copper tubes three inches in diameter extended with both ends open, one presented to the furnace or fire-box, and the other end opening into the chimney. The fire-box, two feet wide and three feet high, attached immediately behind the boiler, was also surrounded with water. The cylinders, two in number, were placed on each side of the boiler in an oblique position, the one end being nearly even with the top of the boiler, and the other end pointing toward the center of the foremost driving pair of wheels, with which the connection was made from the piston-rod by a pin to the outside of the wheel.

The Rocket with its load of water weighed only four and one quarter tons, and was supported upon four wheels (not coupled). The tender was four-wheeled, and similar in shape to a wagon; the foremost part contained the fuel, and the hinder part a water-cask.

The engine, when completed, was shipped to Liverpool and ready for the trial, with the most sanguine expectations of Mr. Stephenson of its success.