Chat Moss was conquered by an ingenious device which practically floated the road-bed upon its spongy surface. Tunnels were driven through the hills, deep cuttings were made wherever needed, a ravine was crossed by a viaduct of brick and stone, and more than threescore bridges were thrown across the streams. All the plans for this complicated work passed under the eye, and many of them took their first form in the mind of the chief, whose skill as a mechanic was for the time sunk in his genius for civil engineering. By dint of the most strenuous application, and by the dominance of a spirit of perseverance which no discouragement or obstacle could daunt, Stephenson brought the road to triumphant completion. The next thing was to convince the directors that the steam locomotive was the proper equipment for a public railway. As a beginning, he persuaded the company to place one of his engines upon its construction trains. The experts who were employed to investigate the many proposed applications of power decided, however, that the most feasible equipment was a series of twenty-one stationary engines located at intervals along the right of way and hauling the cars stage after stage by means of a rope wound upon a drum-the principle of the cable railway which afterwards had its day in our streets. Still Stephenson would give the directors no peace. Finally, in order to settle the question of the practical utility of the traveling engine, the company offered a prize of five hundred pounds for the best locomotive engine, to be awarded after a competitive test upon certain conditions, the most notable of which were: "2. The engine of six tons weight must be able to draw after it, day by day, twenty tons weight at ten miles an hour with a pressure of steam on the boiler not exceeding fifty pounds to the square inch." "4. The engine and boiler must be supported on springs and rest on six wheels, the height of the whole not exceeding fifteen feet to the top of the chimney." "7. The engine must be delivered complete and ready for trial at the Liverpool end of the railway not later than the 1st of October, 1829." "8. The price of the engine must not exceed five hundred and fifty pounds." George Stephenson and his son Robert threw all their resources into the production of the locomotive which was to carry their colors in the contest. The "Rocket" engine, which was built in their Newcastle shop, was fitted with a tubular boiler six feet long and three feet four inches in diameter. The fire-box was two feet wide and three feet high. On each side of the boiler at its rear end was an oblique cylinder, the piston-rods being connected with the outside of the two driving wheels, which were in front. The two rear wheels were about one-half the diameter of the drivers. The tender, also fourwheeled, was a simple affair, the water being carried in a large cask.