Page:The New International Encyclopædia 1st ed. v. 12.djvu/433

* LOCOMOTIVE. 383 LOCOMOTIVE. In later engines Stepheu>ou substituted ripid ucts of combustion were conveyed from a 'fire-box' side rods for the sprocket chain and supported a at one end to a tall stack inches in diameter at portion of the weight of the engine upon pistons the other end. The fire-grate was 3 feet wide contained in vertical cylinders beneath and com- municating freely with the interior of the boiler, the pistons being made to press downward upon the liearings of the axles. The engines built by Stephenson for the Stock- tun and Darlington Railway were substantialljv of the construction just described. They were not very satisfactory machines, and Timothy Hackworth, the locomotive engineer of this road, undertcjok to improve upon them. His engine, !'»■ Itoijul George, was completed in 1827. The iler was a plain cylinder 13 feet long and 4 and 2 feet long in the direction of the boiler, and the firc-bo.x was 3 feet deep and surrounded by a 3-inch water-space which communicated with the boiler proper by means of two external pipes. The cylinders, placed in an inclined position, were fastened to the outside of the boiler near the fire-box, the connecting-rods working upon crank- pins in the driving wheels, which were placed under the front end of the engine. The cylinders were 8 inches in diameter and had a stroke of IGV2 inches; the driving wheels were 4 feet inches in diameter. The exhaust steam from ■t 4 inches in diameter and had a return flue each cylinder was carried through a pipe and like the Hedley engines used on the Wylam Rail- turned upward into the stack. As the result of «ay. There were si.x coupled wheels four feet the success of the Rocket, whose speed exceeded in diameter, and the cylinders, which were placed all expectations, the managers of the Liver- at the end opposite the fire-door and stack, were pool and ilanchester Railway ordered sev- ~n arranged that they overhung the sides of the cral locomotives from the Stephcnsons. These ^ii'iler sulliciently for the downward-projecting engines were, however, larger and heavier than the li-ton-rods to clear it and to connect through ( (iimccting-rods with cranks on the rear pair of wlicels. These rear drivers were rigid, but the ■ illiers had springs. The Royal Gcorr/c had a Rocket, some of them having 10 X 10 inch, and others 11 X 10 inch cylinders, with .5-foot driv- ing wheels and weighing six and one-half and seven tons. The arrangement of the cvlindcrs ^tern into which a portion of the exhaust steam was substantially the same as on the Rocket, rould be turned to heat the feed-water: it also had short-stroke force-pumps worked by eccen- trics, adjustable springs instead of weights upon the safety valves, a single lever reversing gear, and a blast-pipe by which the exhaust cylinder steam created a draught in the smokestack. Nothing further of importance respecting the mechanical development remains to be noted un- til the trials instituted by the Liverpool and Fig. 3. Stephenson's bocket, 1829. Manchester Railway in 1829, which arc noted in the article on R.lLW.iYS. Four locomotives were submitted to undergo this trial and three of them .. __ ., _,_ _, were actually tested. The result of the trial was horizontal," inside cylinder, direct connected lo but they were less inclined. The tubes in the boiler were increased to from 90 to 92 in num- ber and were reduced in diameter to two inches. A smoke-box was also added to the boiler. Before taking up the next series of steps in the mechanical development of the locomotive a moment's attention should be given to the per- formances of the early engines so far mentioned. These are shown in the accompanying table, taken from Zerah Colburn's Locomotive Engineering (London, 1871). The steep inclination of the cylinders of the Stephenson engines caused the machine to rise and sink on the springs at every double stroke, and at moderately high speeds the unsteadiness thus occasioned was considerable. Timothy Hackworth seems to have been the first to con- ceive of the plan of avoiding this trouble by placing the cylinders horizontal. On March 3, 1830. he made plans for a horizontal cylinder engine for the Stockton and Darlington Railway, and laid them before the Stephen.sons. with orders to build an engine in conformity with them. These plans called for an engine with the follow- ing essential characteristics: The boiler was a horizontal cylinder with a single internal flue carrying a grate in one end. and the wheels were four in number, five feet in diameter and coupled. A copper steam-dome was placed on the boiler, and from this feature the engine received its name of the Globe. The forward axle was the driving axle, and it had two cranks between or inside the wheels. The cylinders were horizontal and were located imderneath the rear end of the boiler between or inside the rear wheels. De- fined briefly as to its cylinders, the Globe was a the aivard of the prize to the Rocket, submitted by George Stephenson in the name of his son Robert Stephenson. The Rocket (Fig. 3) was a four-wheel engine supported on springs, and, with a sujiply of water in the boiler, weighed 4 tons 5 hundredweight. The boiler was a horizontal cy- lindrical vessel 6 feet long and 3 feet 4 inches in diameter, traversed by 25 copper tubes 3 inches in diameter, through which the gaseous prod- comotive. The Globe, according to Zerah Col- burn, was not delivered to the Stockton and Dar- lington Railway until after the Stephensons, by whom it was being built, had embodied its ar- rangement of cylinders and driving axle in the Planet, the first inside-cylinder engine made by that firm for the Liverpool and Manchester Rail- way. This engine left Newcastle on September 3, 1830, and was placed in operation on October 4,