Page:The New International Encyclopædia 1st ed. v. 12.djvu/432

* LOCOMOTIVE. 382 LOCOMOTIVE. in 1811 he sent a locomotive to Newcastle-on- Tync, which for some reason was laid aside, and finally set to drive an iron-foundry. In the same year (1811) Matthew Murray built for John Blenkinsop, the proprietor of the jMiddlcton Col- liery, near Leeds, a locomotive in which the steam- FlG. 1. VirnRAYS LOCOMOTIVE FOH BLENKIXSOP S RAIL- WAY, isi:. 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 ,vas placed at one end and out of which the chiinncy rose at the other. There were two steam-cylinders 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 Fig. 2. hedley's engine, I.'^IS. of 30 loaded coal-wagons weighing 94 tons at a speed of three and onelialf miles per hour on a level, and to have hauled 1.5 tons up a grade of 1 foot in 15 feet. While Murray's engine was being operated regularly between Middleton and Leeds, ]Ir. Blackett of Wylam with his engineer, William Hedley, was at work on a locomotive based on the one purchased from Trevithick as noted above. Mr. Hedley made first a series of experiments to determine the sutUciency for railway operation of the adhesion between smootli wheels and smooth rails. These experiment - proving satisfactory, he designed and built hi- first engine in 1813. It had a cast-iron boiler, with a single internal flue, a cjliuder six inches in diameter, and a fl.y-wheel. The engine worker I by the adhesion of its driving wheels upon smooth rails. The lioiler 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. Blackett 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-rods of these cylinders connected with beams the opposite ends of which were hinged, and the connecting-rods were connected to tin' beams midway between the piston-rod connection- 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 181.5 another locomotive was built by Hedley similar to the one just described, but larger ami heavier and having eight wheels instead of four wheels (Fig. 2). The Hedley engines presented two notable ad vanees over previous locomotives. The first wa- the use of a return tubular boiler and the sei ond was the adoption of a smokestack of small diameter in which the exhaust cylinder steam could produce an effective draught. Almost befovf the practicability of Hedlcy's engines had been proved on the ^■ylam Railway, George Steplicii- son had recommended the adoption of locomotive- by the managers of the Killingworth Colliery. 1 1 was finally decided to construct a locomotive, and the work was done in the colliery raachine-shoi)-. after the designs and under the direction of Stephenson. The engine which was finally turned out of the shops was supported on four wlieel-. and had a wrought-iron horizontal boiler 8 feci long and 34 inches in diameter, with "a single internal flue 20 inches in diameter having a grai>' in one end and a 20-inch stack leading out oi the other end. There were two vertical 8 X 24- inch cylinders, the motion of whose pistons was conveyed to the four driving wheels by an ar- rangement almost identical with that used by Hedley. The engine was greatly inferior to both Murray's and Hedley's engines previousl.y dc scribed. Stephenson's first engine was completed on .July 25, 1S14, and the following year he com- pleted a second. Tliis engine was notable be- cause of the fact that the pistons were linknl directly to cranks on the driving wheels, and ihf toothed wheels and chain of gearing previously employed were abandoned. Briefly described, this engine had a horizontal cylindrical boiler with a vertical steam-cylinder mounted on its top at each end. The piston-rod of each cylinder was connected to the centre of a horizontal cross- head extending transversely across the boiler and long enough so that connecting-rods attached to its two ends and extending downward to the cranks on the wheels would clear the boiler on each side. The two pairs of driving wheels were. connected together by an endless sprocket chain to insure uniformity and coincidence of rotation.