consequently, the machine would make no progress. Under this idea, a locomotive was constructed by Mr. Blenkinsop, of Leeds, with racked or tooth-wheels, on one side, which worked into a tooth-rail; the other wheels and rail being smooth. This engine attracted considerable attention, and a similar one was adopted at the colliery at Wylam, where Stephenson was born. It proved, however, of no practical use: the road was in a bad uneven state; the engine often ran off the rail, and was so constantly getting out of order, that horses had often to be sent for to drag both it and the coal-waggons along.

Stephenson, hearing of the locomotive at Wylam, went several times to look at it. He was one of the first to perceive the great, though still undeveloped power of the locomotive engine, and the advantage of employing it on the tramways, instead of horses, to draw the coal-waggons. The tramways were rails, laid down on the roads which led from the collieries to the wharves where the coal was shipped. It was found that waggons could run far more easily upon these rails, than upon ordinary roads; and that one horse employed on a tramway could do the work of six horses on a road. nally, the rails were of wood; but as these were found to wear out very quickly, iron ones had been substituted. After carefully examining the engines constructed by Blenkinsop and Trevithick, Stephenson felt convinced that he could make an engine which would be superior in every respect.

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He consulted Lord Ravensworth, one of the Grand Allies, on the subject, and he having agreed to advance a sum of money for the purpose, Stephenson set to work immediately to construct his "Travelling Engine," as he then called it. He previously made some experiments, to try whether the smooth wheels would have sufficient hold on the rails: these experiments resulted in the con

ONE OF THE EARLIEST LOCOMOTIVES.

clusion, that the weight of the engine itself would give sufficient adhesion for the purpose of traction. The want of skilled workmen to carry out his ideas greatly impeded him in his work, and he was obliged to instruct and train them himself. The

engine was built at the colliery workshop. After ten months of great labour and anxiety, it was completed, and placed on the railway, where it drew eight loaded waggons up a slight incline. It continued to work some time with tolerable success, though it was but a clumsy machine; and Stephenson, having carefully studied its defects, proceeded to construct another engine. In this he made several improvements, the principal of which was the adoption of the "steam blast." By an ingenious contrivance, the waste steam, which before escaped into the air with a hissing sound-the terror of every living thing in the neighbourhood-was conveyed into the chimney, where, by increasing the draught, it made the fire burn faster. The additional heat of the fire caused the steam, which we must remember is the working power of the engine, to expand or increase; the wheels were made to go round more rapidly; and the speed of the engine considerably accelerated. The second locomotive was completed in 1815, the year of the battle of Waterloo,and may be considered as the model of all that have since been produced.

While Stephenson was thus occupied, he still continued his ordinary duties as colliery engineer. The numerous accidents which took place from the explosion of fire-damp in the coal-mines, naturally excited his attention, and led him to consider whether some means for preventing them could not be devised. Fire-damp is an inflammable air,

or gas, which is emitted from the coal, and which explodes on coming into contact with fire. In deep mines, where there is no outlet for it, the fire-damp accumulates in all the fissures of the stone above the coal. In working out the coal the miners often cut across these fissures, when the compressed air bursts out and rushes into the mine, where, should it encounter a lighted candle, or even a spark, it explodes, often blowing up men and horses. Many terrible accidents had occurred from these explosions, in one of which no less than ninety men and boys were either suffocated, or burnt to death. Stephenson was suddenly informed, one day, that a Killingworth pit was on fire he rushed to the spot, and, followed by several of the miners, who had all the greatest confidence in him, descended, at the risk of his life, into the pit, and succeeded in building up the passage where the bad air had accumulated; thus, by his courage and promptitude of action, preventing a serious accident. He now saw more then ever the necessity for a lamp which might be carried in safety by the miners. He made several experiments with the inflammable gas, and at last contrived a lamp, which he felt certain could be used in the mines without the smallest fear of accident. It was tried one evening by Stephenson, his son Robert, and Mr. Wood, the manager of the colliery. They descended into the pit, and approached the most dangerous part of the mine. It was a critical moment, for if the firedamp had exploded, the three men would probably

have been blown up; but Stephenson had perfect confidence in his lamp. He lit the wick and advanced boldly, "calmly venturing his own life, in the determination to discover a mode by which the lives of many might be saved, and death disarmed in these fatal caverns."

Arrived at the place of danger, Stephenson held out the lamp, which flared up for a moment, then flickered, and went out. The attempt was repeated several times with similar results. But Stephenson was not yet satisfied with his lamp: he wished to make one that would go on burning, and not be extinguished, in the fire-damp, so he continued his experiments; and having made the important discovery that flame will not pass through tubes or holes of a very small size, he made another lamp, which he placed in a long tin shade perforated with little holes. When this was introduced into the explosive gas, the gas of course entered the lamp through the holes in the shade, and the air inside the shade caught fire, but the flame, not being able to pass out through the holes in the shade, could not set fire to the bad air which surrounded the lamp, but merely continued to burn inside the shade till the lamp was removed to a purer atmosphere. This lamp was tried at Killingworth on November 30th, 1815, and proved perfectly safe and effective: it received the name of the "Geordy safety-lamp," after its inventor, and was at once introduced into the Killingworth and other neighbouring collieries, where it has been