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Mr. Robert Stephenson, on his arrival in England, proceeded to take charge of the locomotive manufactory at Newcastle, thenceforward devoting himself assiduously to the development of his father's ideas of the locomotive; and, by the great additions made by him to its working powers from time to time, as will afterwards be seen, he contributed in an eminent degree to the ultimate success of the railway system.

During the progress of the important discussion at Liverpool with reference to the kind of power to be employed in working the railway, the father and son were in constant communication, and Robert made frequent visits to Liverpool for the purpose of assisting his father in the preparation of his reports to the board on the subject. Mr. Swanwick remembers the vivid interest of the evening discussions which then took place between father and son as to the best mode of increasing the powers and perfecting the mechanism of the locomotive. He wondered at their quick perception and rapid judgment on each other's suggestions, at the mechanical difficulties which they anticipated and at once provided for in the practical arrangement of the machine; and he speaks of these evenings as most interesting displays of two actively ingenious and able minds, stimulating each other to feats of mechanical invention, by which it was ordained that the locomotive engine should become what it now is. These discussions became more frequent, and still more interesting, after the public prize had been offered for the best loco

the select committee of the House of Commons on the employment of steamcarriages on common roads. He said, “he had been abroad a good many years, and had had nothing to do with steam-carriages until very lately. He had it now, however, in contemplation to do a great deal on common roads, and, with that view, had taken out a patent for an entirely new engine, the arrangements in which were calculated to obviate all the difficulties which had hitherto stood in the way of travelling on common roads.”

chap. xxir.] t PRACTICAL ARRANGEMENTS. 285

motive by the directors of the railway, and the working plans of the engine which they proposed to construct had to be settled. One of the most important considerations in the new engine was the arrangement of the boiler and the extension of its heating surface to enable steam enough to be raised rapidly and continuously, for the purpose of maintaining high rates of speed, -the effect of high pressure engines being ascertained to depend mainly upon the quantity of steam which the boiler can generate, and upon its degree of elasticity when produced. The quantity of steam so generated, it will be obvious, must chiefly depend upon the quantity of fuel consumed in the furnace, and, by consequence, upon the high rate of temperature maintained there. It will be remembered that in Mr. Stephenson's first Killingworth engines he invented and applied the ingenious method of stimulating combustion in the furnace, by throwing the waste steam into the chimney after performing its office in the cylinders, thus accelerating the ascent of the current of air, greatly increasing the draught, and consequently the temperature of the fire. This plan was adopted by him, as we have already seen, as early as 1815; and it was so successful that he himself attributed to it the greater economy of the locomotive as compared with horse power, and hence its continued use upon the Killingworth Railway. This arrangement was adopted, without exception, in all the locomotives subsequently constructed by Mr. Stephenson for the Killingworth, Hetton, and Stockton and Darlington Railways. Though the adoption of the steam blast greatly quickened combustion and contributed to the rapid production of highpressure steam, the limited amount of heating surface presented to the fire was still felt to be an obstacle to the com. plete success of the locomotive engine. Mr. Stephenson endeavoured to overcome this by lengthening the boilers and increasing the surface presented by the flue tubes. He also further endeavoured to meet the difficulty by doubling the flue, the last engine which he constructed for the Stockton and Darlington Railway, previous to the building of the “Rocket,” being constructed with a double tube, which thus presented a considerably greater surface to the fire. The “Lancashire Witch,” built by him for the Bolton and Leigh Railway, and employed in the completion of the Liverpool and Manchester Railway embankments, was also constructed with a double tube, each of which contained a fire and passed longitudinally through the boiler. But this arrangement necessarily led to a considerable increase in the weight of these engines, which amounted to about twelve tons each; and as six tons was the limit allowed for engines admitted to the Liverpool competition, it was clear that the time was come when the Killingworth engine must undergo a further important modification. For many years previous to this period, ingenious mechanics had been engaged in attempting to solve the problem of the best and most economical boiler for the production of high-pressure steam. As early as 1803, Mr. Woolf patented a tubular boiler, which was extensively employed at the Cornish mines, and was found greatly to facilitate the production of steam, by the extension of the heating surface. This boiler consisted of eight tubes placed horizontally in the centre of the longitudinal furnace; and they were so arranged that the whole current of the flame passed over them before it escaped into the chimney. Mr. Woolf stated the object of the arrangement to be, that “the tubes composing the boiler should be so combined and arranged, and the furnace so constructed, as to make the fire, the flame, and the heated air to act around, over, and among the tubes, embracing the largest possible quantity of their surface.” In this arrangement the steam and water were within the tubes. Various

chAP. xxii.] TU BULAR BOILERS. 287

modifications of this boiler were afterwards adopted. The ingenious Trevithick, in his patent of 1815, seems also to have entertained the idea of employing a boiler constructed of “small perpendicular tubes,” with the object of increasing the heating surface. These tubes were to be closed at the bottom, opening into the common reservoir, from whence they were to receive their water, and into which the steam of all the tubes was to be united. It does not, however, appear that any locomotive was ever constructed according to this patent. Mr. W. H. James, a son of the first surveyor of the Liverpool and Manchester Railway, patented a new form of boiler in 1825, the object of which was to increase the heating surface by means of a series of annular tubes placed side by side, and bolted together, so as to form by their union a long cylindrical boiler, in the centre of which, at one end, the fireplace was situated. A model of this tubular boiler was shown by Mr. James to both Mr. Losh and Mr. Stephenson about 1827. Losh expressed the opinion that, if such a boiler could be put to Stephenson's engine, there would be no limits to its power; and Mr. James spoke of a speed of from twenty to thirty miles an hour, at which Mr. Stephenson shook his head, remembering, as no doubt he did, his severe cross-examination and denunciation by counsel before the House of Commons, for venturing to say that twelve miles an hour might be achieved by the locomotive on railways; and he said that was a rate of speed they did not now dare to talk about. Mr. Goldsworthy Gurney, the persevering inventor of steam-carriages for travelling on common roads, also applied the tubular principle extensively in his boiler, the steam being generated within the tubes. Messrs. Summers and Ogle invented a boiler for their turnpike-road steam-carriage, consisting of a series of tubes placed vertically over the furnace, through which the heated air passed before reaching the chimney. The application of the same principle to the railway locomotive, it has been stated by a French author", was first effected by M. Seguin, the engineer of the Lyons and St. Etienne Railway. He claimed to have patented a boiler, in 1828, in which he placed a series of horizontal tubes immersed in the water, through which the hot air passed in streamlets, thus greatly increasing the heating surface, and consequently the evaporative power. Two locomotives had been constructed at Mr. Stephenson's works in Newcastle for the St. Etienne Railway, which were sent to France in 1829. M. Seguin found that, by applying his invention to these engines in conjunction with the steam blast, he was at once enabled greatly to increase their power and speed. The same idea of a tubular boiler had occurred to Mr. Henry Booth, the secretary of the Liverpool and Manchester Railway, who strongly urged its adoption by Mr. Stephenson in the construction of the “Rocket” engine. On the subject of this important combination we cannot do better than here quote the words of Mr. Robert Stephenson himself, in a statement with which he has favoured us: — “After the opening of the Stockton and Darlington, and before that of the Liverpool and Manchester Railway, my father directed his attention to various methods of increasing the evaporative power of the boiler of the locomotive engine. Amongst other attempts he introduced tubes (as had before been done in other engines), small tubes containing water, by which the heating surface was materially increased. Two engines with such tubes were constructed for the St. Etienne Railway, in France, which was in progress of construction in the year 1828; but the expedient was not successful—the tubes became furred with deposit, and burned out. “Other engines, with boilers of a variety of construction, were made, all having in view the increase of the heating

* Lobet, Des Chemins de Fer de France, 1845,

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