the steam-pipe; of the pipe leading to the cylinders; p p the pipes leading to the blast; g g the cylinders; f the funnel or chimney. In fig. 157 we give the back or fire-box end elevation of the same engine. c c the fire-door; d d the starting handles and levers for working the eccentric motions, &c. &c.; ee the gauge-cocks; ff the spring-balance safety-valve; hg the steam-whistle, actuated by the lever i; m m the crankpins, on the driving-wheels, to which the connecting-rods are attached; ii the house or covering for sheltering the engine-men (this arrangement is adopted in all the engines working in the Northern States of America, the climate being too severe in winter to allow the men to be exposed to all weathers, as with us). In fig. 158 we give an elevation of another form of American locomotive: aa the cylinder and valve-casing; b the piston cross-head; c the connecting-rod; d d the connecting-rod coupling the wheels together. In fig. 159 we give a sketch of a first-class locomotive passenger engine on Crampton's patent principle, as used on the London and Northern and Western Railway, showing the connection of engine and tender. In fig. 160 a form of engine as used for short journeys is shown; in this species CHAPTER VI. STEAM-NAVIGATION AND THE MARINE ENGINE. UNDER the present division of our treatise we purpose giving a few historical notes as to the introduction of the steam-engine for the purposes of navigation, preliminary to the illustrations and descriptions of the modern "marine engine." From the limited space now at our disposal, we shall be prevented from going so deeply into the historical details as might by some be considered necessary; but we shall nevertheless endeavour to notice the most important of these. For many years previous to the application of the steam-engine to the propelling of boats, it had been a favourite object with mechanics, the substitution of sundry mechanical contrivances for sails. The most noticeable of these was the revolving wheel with float-boards on its periphery, which acted, on being immersed in the water, so as to move the boat forward: this, modified somewhat in its arrangements and construction, is identical in principle with the "paddle-wheel" of the modern steam-boat. The various contrivances introduced for boat-propulsion were actuated either by manual labour or that of horses, through the intervention of simple mechanical arrangements. The earliest notice we have of an attempt to substitute the power of steam for these methods of working is that of Blasco de Garay, to whose invention we have already alluded in the first chapter. Captain Savery, in the Miner's Friend, alluded to the capability of steam as a power for moving steam-boats; but it does not appear that he entered further into the matter than making a mere suggestion. Denis Papin, during his residence in England, is said to have constructed a model by which a steam-piston moving in a cylinder gave motion to the axle of the paddle-wheels; a rack was placed on the piston-rod, working into a pinion fastened on the axle of the revolving paddles. He employed two or three steam-cylinders; and when the piston of the one was ascending, that of the other was working downwards; and as they would give contrary motions, one was detached while the other was in action; and by this means the motion could be made continuous and tolerably regular. In 1737 Jonathan Hall published "a description and draught of a newinvented machine for carrying vessels or ships out of or into any harbour, port, or river, against wind or tide, or in a calm." In this steam-boat the engine used was an atmospheric one, rotatory motion being obtained by a continuous arrangement of pulleys and cords or bands. We give in fig. 161 a diagram illustrative of the general appearance of this boat. From the imperfect mechanical arrangements, and the defects of the atmospheric as a rotative engine, this attempt at steam-boat propulsion was soon abandoned, if indeed it ever went beyond a mere speculation on paper. Passing over various unsuccessful attempts made in America by Fitch and Ramsey, in 1785-1793; the Earl of Stanhope in England, in 1795; and of the Chancellor Livingstone and the celebrated Brunel on the Hudson in America, in 1797,-we proceed to notice the first successful steamengine. We must, however, go back for a few years prior to the lastmentioned date. In 1787, Mr. Patrick Miller, of Dalswinton, a gentleman who devoted much of his time to experiments in the improvement of artil fig. 161. lery and naval architecture, published a description, with drawings, of a triple vessel moved with wheels." Convinced that, to give his invention every fair chance, it was necessary to employ some force greater than that of manual labour, he threw out the suggestion of employing the steamengine for the purpose of moving the wheels; the force of steam, amidst other means proposed, presented itself, however, to his mind "as at once the most potent, the most certain, and the most manageable." "In Miller's family," says his son, in the narrative published in the Edinburgh Philosophical Journal in 1824, "there was at this time, as tutor to his youngest children, Mr. James Taylor, who had bestowed much attention on the steam-engine, and who was in the custom of assisting Miller in his experiments on naval architecture and the sailing of boats. One day, in the very heat of a keen and breathless contest in which they were engaged with a boat on the Leith establishment, this individual called out to his patron, 'that they only wanted the assistance of a steam-engine to beat their opponents;' for the power of the wheels did not move the boat faster than five miles an hour. This was not lost on Miller, and it led to many discussions on the subject; and it was under very confident belief in its success that the allusion was made to it in the book already mentioned. In making his first experiments, Miller deemed it advisable in every point of view to begin upon a small scale, yet a scale quite sufficient to deter |