Both ideas seem to have been realised in different parts of the bog. Joy took the place of despair, and triumph exulted over discouragement, as at length the solid mass appeared through the surface. Furthermore, the expense was found to be none so costly after all. No doubt any quantity of turf could be obtained from the surrounding parts of the Moss and dried.
At another part of the railway called Parr Moss an embankment about a mile and a-half was formed by pouring into it stone and clay from a “cutting” in the neighbourhood. In some places twenty-five feet of earth was thus concealed beneath the Moss. The eye of the engineer had as it were pierced through the bog and seen that his solid bank was steadily being built up there.
Before, however, the road across Chat Moss was fairly opened, the trial of locomotives for the prize of £500 had taken place. The fateful day was the 1st day of October, 1829, and the competition was held at Rainhill. A grand stand was erected, and the side of the railway was crowded. Thousands of spectators were present. The future of the locomotive was to be decided on this momentous occasion.
Now, hitherto the difficulty in the locomotive had been to supply a steady and sufficient supply of steam to work the engine quickly and attain high speed and power. Partly, this had been accomplished by Stephenson’s device of the steam-blast in the funnel. But something more was needed.
That requirement was found in the tubular boiler. If the long locomotive boiler were pierced with tubes from end to end, it is clear that the amount of heating surface offered to the action of the fire would be greatly increased. It was this idea which was utilised in the “Rocket,” the engine with which Stephenson competed at Rainhill, and utilised more perfectly than ever before.
Trevithick himself seems to have invented something of the kind, and M. Seguin, the engineer of the St. Etienne and Lyons Railway utilised a similar method. But Henry Booth, the secretary of the railway which Stephenson was then building, invented a tubular boiler without, it is said, knowing anything of Seguin’s plan, and Stephenson who had already experimented in the same direction, adopted Booth’s method.
At first it was a failure. The boiler, fitted with tubes through which the hot air could pass, leaked disastrously, and Stephenson’s son, Robert, wrote to his father in despair. But again George said “persevere,” and he suggested a plan for conquering the difficulty. Again, it was a simple, but as the event proved, an effective plan.
The copper tubes were merely to be fitted tightly to holes bored in the boiler and soldered in. The heat caused the copper to expand and the result was a very strong and water-tight boiler. There were twenty-five of these tubes, each three inches in diameter, and placed in the lower portion of the boiler, leading from the furnace to the funnel. Water also surrounded the furnace. Further, the nozzles of the steam-blast pipes were contracted so as to increase the power of the blast, and consequently raise the strength of the draught to the fire.
