The next great advance was to place the steam-engine on wheels, to enable it to haul and accompany the trucks. Crude and imperfect as the primitive locomotives must have been, a very short trial of them 186 served to show that the rails of cast-iron then in use were totally unfitted to form a trackway for the newly invented machines. The short fish-bellied cast-iron rails were made in lengths merely to extend from chair to chair; they possessed little or no continuity, and from the inherent brittleness of the material they were constantly breaking and giving way under the increased weights imposed upon them. It became necessary to adopt a more reliable material, and attention was naturally turned to forged or wrought iron. The suggestion once made was promptly responded to by the iron makers. Special machinery was designed and constructed, and very soon wrought-iron rails were manufactured in large quantities. At first they were made very similar in section to the fish-belly cast-iron rails, but in lengths to extend over three or four sleepers. The increased length gave greater stability to the road, and permitted an increase of speed. The manifest superiority of the wrought-iron rails led to their universal adoption, and a great impetus was thus given to their manufacture. Improvements were made in the machinery for rolling, and more care was bestowed in the working of the iron. Changes were made in the section of the rails; the fish-belly form was discarded, and a double-head type was introduced to give more lateral stiffness. At this period in its history the capabilities of the _iron road_ began to be more fully recognized, and the supporters of the system foresaw a great future success, both for the conveyance of passengers as well as goods. Hitherto the tramroads or railroads had been used for minerals and merchandize only, but it was now claimed that on a carefully constructed line, and with improved locomotives and rolling-stock, it would be possible to convey passengers more conveniently and rapidly than by any other method. [Illustration: Fig. 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258] Inventive minds were at work to accomplish so desirable an object, and public enterprise was forthcoming to provide funds for the purpose. The successful working of the first passenger line formed the dawn of a new era in travelling, and similar lines were soon projected for other places. The wrought-iron rails in use at this time were generally of a double head form, and rarely exceeded 12 or 15 feet in length. They were held by wooden pegs in cast-iron chairs, which were secured to timber cross-sleepers or stone blocks, as shown in Figs. 188 234 and 235. They were light in section, and it is stated that the first rails on the Liverpool and Manchester Railway weighed only 33 lbs. per yard.