George Stephenson’s connection with the locomotive, however, was even now beginning.  Already, in 1816, he and his boy had tried a somewhat higher flight of mechanical and scientific skill than usual, in the construction of a sun-dial, which involves a considerable amount of careful mathematical work; and now George found that the subject of locomotive engines was being forced by circumstances upon his attention.  From the moment he was appointed engine-wright of the Killingworth collieries, he began to think about all possible means of hauling coal at cheaper rates from the pit’s mouth to the shipping place on the river.  For that humble object alone—­an object that lay wholly within the line of his own special business—­did the great railway projector set out upon his investigations into the possibilities of the locomotive.  Indeed, in its earliest origin, the locomotive was almost entirely connected with coals and mining; its application to passenger traffic on the large scale was quite a later and secondary consideration.  It was only by accident, so to speak, that the true capabilities of railways were finally discovered in the actual course of their practical employment.

George Stephenson was not the first person to construct either a locomotive or a tramway.  Both were already in use, in more or less rude forms, at several collieries.  But he was the first person to bring the two to such a pitch of perfection, that what had been at first a mere clumsy mining contrivance, became developed into a smooth and easy iron highway for the rapid and convenient conveyance of goods and passengers over immense distances.  Of course, this great invention, like all other great inventions, was not the work of one day or one man.  Many previous heads had helped to prepare the way for George Stephenson; and George Stephenson himself had been working at the subject for many years before he even reached the first stage of realized endeavour.  As early as 1814 he constructed his first locomotive at Killingworth colliery; it was not until 1822 that he laid the first rail of his first large line, the Stockton and Darlington Railway.

Stephenson’s earliest important improvement in the locomotive consisted in his invention of what is called the steam-blast, by which the steam is made to increase the draught of the fire, and so largely add to the effectiveness of the engine.  It was this invention that enabled him at last to make the railway into the great carrier of the world, and to begin the greatest social and commercial upheaval that has ever occurred in the whole history of the human race.