This circular was printed and published throughout the kingdom, and a considerable number of engines were constructed to compete at the trial, which was proposed to take place October 1, 1829, but which was deferred to the 6th of that month. Only four engines, however, were finally entered on the day of the trial. These were the "Novelty," constructed by Messrs. Braithwaite & Ericsson, the latter being the distinguished engineer who subsequently came to the United States to introduce screw-propulsion, and, later, the monitor system of iron-clads; the "Rocket," built from Stephenson's plans; and the "Sanspareil" and the "Perseverance," built by Hackworth and Burstall, respectively. The "Sanspareil," which was built under the direction of Timothy Hackworth, one of Stephenson's earlier foremen, resembled the engine built by the latter for the Stockton & Darlington road, but was heavier than had been stipulated, was not ready for work when called, and, when finally set at work, proved to be very extravagant in its use of fuel, partly in consequence of the extreme intensity of its blast, which caused the expulsion of unconsumed coals from the furnace. The "Perseverance" could not attain the specified speed, and was withdrawn. [Illustration: FIG. 54.--The "Novelty," 1829.] The "Novelty" was apparently a well-designed and for that time a remarkably well-proportioned machine. _A_, in Fig. 54, is the boiler, _D_ the steam-cylinders, _E_ a heater. Its weight but slightly exceeded three tons, and it was a "tank engine," carrying its own fuel and water at _B_. A forced draught was obtained by means of the bellows, _C_. This engine was run over the line at the rate of about 28 miles an hour at times, but its blowing apparatus failed, and the "Rocket" held the track alone. A later trial still left the "Rocket" alone in the field. The "Rocket" (Fig. 55) was built at the works of Robert Stephenson & Co., at Newcastle-upon-Tyne. The boiler was given considerable heating-surface by the introduction of 25 3-inch copper tubes, at the suggestion of Henry Booth, secretary of the railroad company. The blast was altered by gradually closing in the opening at the extremity of the exhaust-pipe, and thus "sharpening" it until it was found to have the requisite intensity. The effect of this modification of the shape of the pipe was observed carefully by means of syphon water-gauges attached to the chimney. The draft was finally given such an intensity as to raise the water 3 inches in the tube of the draught-gauge. The total length of the boiler was 6 feet, its diameter 40 inches. The fire-box was attached to the rear of the boiler, and was 3 feet high and 2 feet wide, with water-legs to protect its side-sheets from injury by overheating. The cylinders, as seen in the sketch, were inclined, and coupled to a single pair of driving-wheels. A tender, attached to the engine, carried the fuel and water. The engine weighed less than 4-1/2 tons.