RAILROAD 171 of wrought-iron rails. This took place in 1808, though it was not till 1820 that suitable ma- chinery was devised for rolling rails into other than flat shapes. This was a most important step, as cast-iron rails could not be made straight in greater lengths than 4 or 5 ft., and consequently required many cross ties and joints; whereas the introduction of wrought iron permitted the increase of the length of the rails by successive steps, till with the per- fected processes of the present day they are . made of iron and steel 30 ft. and even longer if required. With the improvements in the machinery for rolling rails, it became possi- ble to make the new and improved forms of rails rendered necessary by the substitution of steam carriages for horses, which had hitherto been almost exclusively used. The force of gravity was utilized in exceptional instances where the roads sloped gradually from the col- lieries, and by the adaptation of ropes and wheels or windlasses the descending loaded cars were made to draw up the empty ones. Watt suggested the possibility of constructing steam carriages in 1759, and patented one in 1784. Oliver Evans of Philadelphia patented a steam wagon in 1782, the drawings and speci- fications of which were sent to England in 1787, and again in l794-'5. In 1784 Murdoch, Watt's assistant, constructed a working model of Watt's carriage. In 1802 Trevithick and Vivian patented a high-pressure locomotive engine, and in 1804 built one for the Merthyr- Tydfil railway in S. Wales, which was found to work well with light loads upon a level sur- face or moderate grades, but if more severely tasked the wheels would slip without advan- cing. A check was thus put upon their use until some method could be devised by which they might obtain a hold upon the track or otherwise push themselves forward. A rack laid along the side of the rail, into which worked a toothed wheel fitted to the loco- motive, was tried in 1811 on a colliery line near Leeds, but the friction was too great, and it was abandoned. The next year engines were tried with eight driving wheels for securing the required adhesion; and about the same time other engines were constructed with le- vers projecting behind and working alternately like the hind legs of a horse. In 1814 and 1815 engines with plain wheels were found to work successfully on some of the northern roads; but no other application was made of them than for transporting the coal and ore wagons of the mines. In 1814 George Stephenson con- structed his first locomotive, which travelled at the rate of 6 m. an hour; in 1826 Seguin, a French engineer, built locomotives in which he increased the evaporative power of the engine by small tubes passing from the fire box to the chimney ; in 1829 Stephenson and Booth built the engine Rocket, weighing 4 tons 5 cwt., which travelled at a rate of 35 m. an hour; in 1834 the Firefly drew a loaded train at the rate of 20 m. an hour ; in 1839 the North Star moved with a velocity of 37 m. an hour; and at the present time locomotives have at- tained a speed of 75 m., and for short distances even greater velocities have been reached. (See STEAM CARRIAGE.) The first railroad for carrying passengers was the Stockton and Dar- Flrst Railroad Passenger Car. lington road, built by Edward Pease and George Stephenson, and opened Sept. 27, 1825. The Liverpool and Manchester road, commenced in 1826, and opened Sept. 15, 1830, was in- tended by its proprietors to carry passengers at a high speed. As it would be expensive to do this with horses, it was thought that sta- tionary steam engines placed at short inter- vals along the road might be used for the pur- pose of drawing the trains ; but the success of the locomotives built by Stephenson, Ericsson, and others, under the stimulus of a premium of 500 offered by the railway company, caused this plan to be abandoned, and gave rise to the establishment of a new system of locomotion of almost limitless speed and capacity. The small engines at first used were soon found inade- quate to the service demanded of them, and were replaced by others of larger size and greater weight ; some now employed have 10 or 12 wheels and weigh in some cases as much as 75 tons, and there are many in all parts of the world weighing 30, 40, and 50 tons, according to their pattern and uses. Finally, owing to the great weight and high speed of these loco- motives, and the consequent wear and tear upon themselves and the rails, joints, and bridges, it has come to be a grave question as to whether they have not grown beyond the limit of economy, and should not therefore be reduced in size and weight. The gauge of the Liverpool and Manchester railway was fixed by Stephenson at 4 ft. 8^ in., that being about the common gauge of the ordinary road wagons of the day. It was afterward generally adopted throughout the world, partly for the same reason that influenced Stephenson, but mostly because the English were the first locomotive builders for foreign countries, and stoutly ad- hered to the precedent set them by their most distinguished engineer. Later the merit of this precedent was disputed by Brunei and other able engineers, who claimed that a broader
