ways designated to carry both standard-gauge and narrow-gauge cars.
Early History. The development of the steam railway is ordinarily dated from the opening to traffic of the Stockton and Darlington Railway, in England, in 1825. The railway, however, had a history long before this date. Indeed, the Stockton and Darlington Railway, and its immediate successor, the Liverpool and Manchester Railway, were comparatively perfect developments of the art of railway transportation. To understand fully the growth of the steam railway it is, therefore, important to review its early history. This may be roughly divided into two phases, namely, the development of railway track and the evolution of railway motive power. To prevent confusion, each of these lines of growth will be considered separately so far as is practicable, but it will be understood that they progressed simultaneously.
Early in the sixteenth century rails of timber were laid at the collieries near Newcastle-on-Tyne, England, over which by means of bulky carts provided with rollers one horse could draw four or five tons of coal. The first notable improvement of this crude railway consisted in securing these wooden rails by pegs to cross-ties placed two or three feet apart, and in fastening on top of the rails proper, which were about six inches square, strips of hard wood which could be removed when worn and replaced with new strips without disturbing the remainder of the structure. In the year 1735 flat iron bars were substituted to some extent for this upper strip of wood, and in 1767 cast-iron bars were generally substituted for the entire wooden rail. At first these bars were flat and about 4 inches wide, 1¾ inches thick, and 4 or 5 feet long, with holes for the spikes, but after a few years they were made with a ridge along the outside edge to prevent the wheels from leaving the track. Subsequently, the flange was transferred to the inside edge of the rail. In 1789 William Jessup introduced a new form of cast-iron rail in which the depth was greater than the width, which led to the name of edge rail being given to it. These rails were cast with a head 1¾ inches wide carried by a thin web deeper at the middle of the rail than at the ends. At first these rails were bolted or pinned directly to the ties, but soon afterwards they were arranged to be supported by cast-iron pedestals or chairs spiked to the ties and having a slot at the top in which the web of the rail was set and secured by a wedge. The rails were made without flanges and instead flanges were placed on the wheels. Owing to the short lengths in which these rails had to be cast, the joints were numerous, a very important objection in railway track, and besides this the material was too brittle to carry safely heavy loads at high speed. The development of the iron industry partly remedied these faults about 1820 by furnishing malleable or wrought iron from which tough rails could be rolled up to lengths of 15 feet. At the end of the first quarter of the nineteenth century, therefore, the standard railway track is found to have consisted of wrought-iron edge rails about 15 feet long, fastened by keys into cast-iron chairs, which were in turn bolted down to stone blocks or wooden sills, spaced about three feet apart. The gauge of the track, that is the distance apart of the rails measured between the inner edge of their heads, was 4 feet 8½ inches, which ultimately became the standard gauge of railway track in England and America. It will be observed that the essential characteristics of the modern steam railway track had been established by 1825, and that it only remained for future knowledge and experience to develop and perfect these features.
The great advance of the wrought-iron edge rail over previous forms of rails gave the first strong impetus to the development of a means of motive power for railways which would be superior to haulage by horses. The possibility of using steam locomotives at once suggested itself. Steam carriages for operation on common roads had been constructed long previous to 1825. (See Automobile; Locomotive.) As early as 1804 Richard Trevithick had built a locomotive engine, which at its first trial upon the Merthyr and Tydvil Railway, in Wales, had hauled wagons containing ten tons of coal at the rate of five miles per hour. In 1812 locomotives were used by Blenkinsop to haul coal between the Middleton collieries and Leeds, and also by Blackett at Wylam. None of these locomotives were satisfactory. In 1814 George Stephenson built his first engine and put it in operation on the Killingworth Railway, where it hauled a load of 35 tons at the rate of four miles per hour on a grade of 1 in 450. Stephenson continued to build locomotives, each of them an improvement over its predecessor, and had them working regularly on the Killingworth Railway, although they did not supersede the work of horses. The next step in advance in the use of the locomotive was made on the historic Stockton and Darlington Railway, the construction of which marked the advent of a new era in railway transportation. Before passing from the early history of railways to this new era it will be interesting to summarize briefly the status of railway transportation at the time. In 1825 the existing railways of Great Britain were 28 in number, ranging in length from 4 to 35 miles, and amounting in the aggregate to about 400 miles. These roads were used almost exclusively for the transportation of mineral products. With the few exceptions previously noted, the universal motive power employed was haulage by horses.
Period of Development. The Stockton and Darlington Railway, 25 miles long, was opened for traffic in 1825, the line having been constructed under the direction of George Stephenson, as chief engineer. Considering Stephenson's previous work with steam locomotives on the Killingworth Railway, it was not surprising that he should attempt to use similar motive power on the new line. His success in the attempt was considerable. On the opening of the road the Stephenson engine hauled a train composed of 22 wagons filled with passengers and 12 wagons loaded with coal, making an aggregate weight of about 90 tons, at an average speed of five miles per hour and a maximum speed of 12 miles per hour. Notwithstanding the flattering showing made by the locomotive engine in this trial trip, that form of motive power was employed only to a small extent in the immediate future operation of the railway. It could not compete in economy with haulage by horses, and for some time all passengers and mixed freight were so hauled, the locomotive being used only to handle a portion of the coal traffic. The important role played by the Stockton and Darlington Railway,
