EARLY HISTORY AND DEVELOPMENT. The loco motive engine was first developed for use on com mon roads (see AUTOMOBILE) ; it was not until 1SO4 that it was applied to railway operation by Richard Trevithick. Little is definitely known of the Trevithick locomotive tirst used on the Merthyr-Tydvil Railway beyond the fact that it had a return tubular boiler, a tall smoke stack, into which the cylinder steam exhaust ed, and a cylinder eight inches in diameter, and four and one-half foot stroke. Another point which deserves to be noticed is that Trevithick recognized the sufficiency of the adhesion be tween a plain cylindrical wheel and a smooth rail for securing the necessary tractive power, but he recognized also that under certain condi• lions this adhesion be insufficient and provided for toothed wheels and rails to be used in such eases. Trevithick's locomotive made no more than one or two trips on the Alerthyr-Tydvil Railway. Commercially it was regarded as a failure. In hope of something hotter growing out of it. however. Mr. Blackett of the Wylam Colliery. near Newcastle-on-Tyne, wrote to Trevithiek in Cornwall in I809 with reference to the construction of another engine. Trevithiek at first refused to consider the mat ter, hut apparently reconsidered his decision: for in 1811 he sent a locomotive to Newcastle-on Tyne, which for some reason was laid aside, and finally set to drive an iron-foundry. In the same year (1S11) Matthew Murray built for John Illenkinsop, the proprietor of the Middleton Col liery, near Leeds, a locomotive in which the steam cylinders operated a toothed wheel which engaged with a toothed rail laid alongside one of the track-rails. In Murray's locomotive the boiler was cylindrical and horizontal with slightly con vex ends. and had a single internal flue in which the fire-grate was placed at one end and out of which the chimney rose at the other. There were two steam-•ylinders located on top of the boiler and projecting downward into the boiler. The cylinders were upright and double-acting. Each piston - rod was so connected with a pair of cranks, one on each side of the engine, as to drive a toothed wheel, the two wheels thus driven by the two pistons being made to gear with a larger toothed wheel which meshed with the toothed rail. The engine was carried on four smooth
wheels in the manner of an ordinary road-wagon. Murray's engine is stated to have hauled a load of 30 loaded coal-wagons weighing 04 tons at a speed of three and one-half miles per hour on a level, and to have hauled 15 tons up a grade of 1 foot in 15 feet. While Murray's engine was being operated regularly between Middleton and Leeds, Mr. Blackett of Wylam with his engineer, William Hedley, was at work on a locomotive based on the one purchased from Trevithiek as noted above. Mr. Nedlcy made first a series of experiments to determine the sufficiency for railway operation of the adhesion between smooth wheels and smooth rails. These experiments proving satisfactory, lie designed and built his first engine iu 1813. It had a cast-iron boiler, with a single internal flue, a cylinder six inches in diameter. and a fly-wheel. The engine worked by the adhesion of its driving wheels upon smooth rails. The boiler was deficient in steaming power and serious inconvenience was felt from the want of a second cylinder. The results were such, how ever, as to encourage Mr. Blaekett to commission Mr. Hedley to make another and better engine. This engine had a wrought-iron boiler with a return flue, the chimney being placed at the same end as the fire-box. Two vertical cylinders were employed, one on each side of the engine. The piston-roils of these cylinders connected with beams the opposite ends of which were binged. and the connecting-rods were connected to the beams midway between the piston-rod connections and the hinges and extended downward to cranks operating toothed wheels which, by means of a chain of gear-wheels, operated the two pairs of wheels upon which the engine was carried. In 1S15 another locomotive was built by Hedley similar to the one just described, but larger and heavier and having eight wheels instead of four wheels (Fig. 2).