The idea of constructing a steam-engine to run on the colliery tram-roads leading to the shipping-place was now receiving considerable attention from the engineering community. Several schemes had been propounded, and engines actually made; but none of them had been brought into use. A mistaken notion prevailed that the plain round wheels of an engine would slip round without catching hold of the rails, and that thus no progress would be made; but George Stephenson soon became convinced that the weight of the engine would of itself be sufficient to press the wheels to the rails, so that they could not fail to bite. He turned the subject over and over in his mind, tested his conceptions by countless experiments, and at length completed his scheme. Money for the construction of a locomotive engine on his plan having been supplied by Lord Ravensworth, one was made after many difficulties, and placed upon the tram-road at Killingworth, where it drew a load of 30 tons up a somewhat steep gradient at the rate of four miles an hour. Still there was very little saving in cost, and little advance in speed as compared with horse-power; but in a second one, which Stephenson quickly set about constructing, he turned the waste steam into the chimney to increase the draught, and thus puff the fuel into a brisker flame, and create a larger volume of steam to propel the locomotive. The fundamental principles of the engine thus formed remain in operation to this day; and it may in truth be termed the progenitor of the great locomotive family. In 1821 George Stephenson got the appointment of engineer, with L300 of salary, to the Stockton and Darlington Railway Company, in the Act of Parliament for which power was given to use locomotive engines, if needful, either for the conveyance of goods or passengers. When the line was opened, it was worked partly by horses and partly by locomotive and stationary engines. This led to a partnership between Mr. Edward Pease of Darlington, the chief projector of the line, and Stephenson, in a locomotive manufactory in Newcastle,--for many years the only one of the kind in existence. Meanwhile, young Robert Stephenson, having spent a year or two in gaining a practical acquaintance with the machinery and working of a colliery, went to the University of Edinburgh, where he spent a session in attending the courses of lectures on chemistry, natural philosophy, and geology. He made the best of his opportunities; and that he might profit to the utmost by the lectures, he studied short-hand, and took them all down _verbatim_, transcribing his notes every evening before he went to bed. Robert brought home the prize for mathematics, and showed he had made so much progress at college that, though the L80 which the session cost was a large sum to his father at that time, George never failed, then or afterwards, to declare that it was one of the best investments he had ever made.