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. 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 same object of increasing the heating surface. These tubes were to be closed at the bottom, and open into a common reservoir, from which they were to receive their water, and where the steam of all the tubes was to be united. About the same time George Stephenson was trying the effect of introducing small tubes in the boilers of his locomotives, with the object of increasing their evaporative power. Thus, in 1829, he sent to France two engines constructed at the Newcastle works for the Lyons and St. Etienne Railway, in the boilers of which tubes were placed containing water. The heating surface was thus found to be materially increased; but the expedient was not successful, for the tubes, becoming furred with deposit, shortly burned out and were removed. It was then that M. Seguin, the engineer of the railway, pursuing the same idea, adopted his plan of employing horizontal tubes through which the heated air passed in streamlets. Mr. Henry Booth, the secretary of the Liverpool and Manchester Railway, without any knowledge of M. Seguin’s proceedings, next devised his plan of a tubular boiler, which he brought under the notice of Mr. Stephenson, who at once adopted it, and settled the mode in which the fire-box and tubes were to be mutually arranged and connected. This plan was adopted in the construction of the celebrated “Rocket” engine, the building of which was immediately proceeded with at the Newcastle works.