Stephenson had long been a partner in a locomotive factory at Newcastle, which had hitherto proved a losing concern to the owners. There was little or no market for their article, and they struggled on, year after year, waiting for better times. Nobody saw better times but Stephenson. He saw them ahead, shooting through the gloomy clouds of indifference and prejudice. And now, he calculated, it was very near. So he sent Robert to Newcastle to take charge of the works there, and construct an engine that would make good all his words.
It was a critical moment, but he had no fears of the result. Robert often came to Liverpool to consult with his father, and long and interesting discussions took place between father and son concerning the best modes of increasing and perfecting the powers of the mechanism. One thing wanted was greater speed; and this could only be gained by increasing the quantity and the quality of the steam. For this effect a greater heating surface was necessary, and mechanics had long been experimenting to find the best and most economical boiler for high-pressure engines.
Young James, son of Mr. James, who, when the new Liverpool and Manchester route was talked of, was the first to discover and acknowledge George Stephenson's genius, made the model of an improved boiler, which he showed to the Stephensons. Perhaps he was one of the boys who went to Killingworth with his father to see the wonders of "Puffing Billy," and whose terrors at the snorting monster were only smoothed by a pleasant and harmless ride on his back. Whether this gave him a taste for steam-engines we do not know. At any rate, he introduces himself to our notice now, with a patented model of an improved boiler in his hand, which Stephenson thinks it may be worth his while to make trial of. "Try it," exclaimed the young inventor, "try it, and there will be no limit to your speed. Think of thirty miles an hour!"
"Don't speak of thirty miles an hour," rejoined Stephenson; "I should not dare talk about such a thing aloud." For I suppose he could hardly forget how parliamentary committees had branded him as a fool and a madman for broaching such beliefs.
The improved boiler was what is called a multitubular boiler. You do not understand that, I suppose. An iron boiler is cast, six feet long, and three feet and a third in diameter. It is to be filled half full of water. Through this lower half there run twenty-five copper tubes, each about three inches in diameter, opened at one end to the fire, through which the heat passes to the chimney at the other end. You see this would present a great deal of heating surface to the water, causing it to boil and steam off with great rapidity. The invention was not a sudden growth, as no inventions are. Fire-tubes serving this use started in several fertile minds about the same time, and several persons claimed the honour of the invention; but it was Stephenson's practical mind which put it into good working order, and made it available; for he told Robert to try it in his new locomotive.
He did. The tubes were of copper, manufactured by a Newcastle coppersmith, and carefully inserted into the ends of the boiler by screws. Water was put into the boiler, and in order to be sure there was no leaking, a pressure was put on the water; when lo, the water squirted out at every screw, and the factory floor was deluged. Poor Robert was in despair. He sat down and wrote his father that the whole thing was a failure.
A failure indeed! Back came a letter by the next post telling him to "go ahead and try again!" The letter, moreover, suggested a remedy for the disaster—fastening the tubes into the boiler by fitting them snugly into holes bored for the purpose, and soldering up the edges. And it proved to be precisely what Robert himself had thought of, after the first bitter wave of disappointment had subsided. So he took heart and went to work again. Success crowned his efforts. A heavy pressure was put on the water, and not a drop oozed out. The boiler was quite water-tight.
This is precisely the kind of boiler now in use: some have fifty tubes; the largest engines one hundred and fifty.
Various other improvements were incorporated into the new engine, which, as you do not probably understand much about machinery, will not particularly interest you.