Such was the growth of the railway, which, it will be observed, originated in necessity, and was modified according to experience; progress in this, as in all departments of mechanics, having been effected by the exertions of many men, one generation entering upon the labours of that which preceded it, and carrying them onward to further stages of improvement. We shall afterwards find that the invention of the locomotive was made by like successive steps. It was not the invention of one man, but of a succession of men, each working at the proper hour, and according to the needs of that hour; one inventor interpreting only the first word of the problem which his successors were to solve after long and laborious efforts and experiments. “The locomotive is not the invention of one man,” said Robert Stephenson at Newcastle, “but of a nation of mechanical engineers.” The same circumstances which led to the rapid extension of railways in the coal districts of the north tended to direct the attention of the mining engineers to the early development of the powers of the steam-engine as a useful instrument of motive power. The necessity which existed for a more effective method of hauling the coals from the pits to the shipping places was constantly present to many minds; and the daily pursuits of a large class of mechanics occupied in the management of steam power, by which the coal was raised from the pits, and the mines were pumped clear of water, had the effect of directing their attention to the same agency as the best means for accomplishing that object. Among the upper-ground workmen employed at the coal-pits, the principal are the firemen, enginemen, and brakes-men, who fire and work the engines, and superintend the machinery by means of which the collieries are worked. Previous to the introduction of the steam-engine the usual machine employed for the purpose was what is called a “gin.” The gin consists of a large drum placed horizontally, round which ropes attached to buckets and corves are wound, which are thus drawn up or sent down the shafts by a horse travelling in a circular track or “gin race.” This method was employed for drawing up both coals and water, and it is still used for the same purpose in small collieries; but where the quantity of water to be raised is great, pumps worked by steam power are called into requisition.