Historic Inventions

by Rupert Sargent Holland

He had already, as engine-wright of the Killingworth Colliery, applied the surplus power of a pumping steam-engine to the work of drawing coal from the deeper workings of the mine, thereby saving a great amount of manual and horse labor. When the coal was drawn up it had to be transported to the quays along the Tyne, and to simplify this Stephenson laid down inclined planes so that a train of full wagons moving down the incline was able to draw up another train of empty wagons. But this would only work over a short distance, and was in itself a small saving in effort.

The engines that Mr. Blackett had built, using Trevethick’s model as a basis, were working daily near the Killingworth Colliery, and Stephenson frequently went over to see them. He studied Mr. Blackett’s latest locomotive, nicknamed “Black Billy,” with the greatest care, and then told his friend Jonathan Foster that he was convinced that he could build a better engine than Trevethick’s, one that would work more effectively and cheaply and draw a train of cars more steadily.

He also had the advantage of seeing other primitive locomotives that were being tried at different places near Newcastle. One of these, known as Blenkinsop’s Leeds engine, ran on a tramway, and would draw sixteen wagons with a weight of seventy tons at the rate of about three miles an hour. But the Blenkinsop engine was found to be very unsteady, and tore up the tram-rails, and when its boiler blew up the owner decided that the engine was not worth the cost of repair. Stephenson, however, drew some useful points from it, as well as from each of the other models he saw, and proposed to himself to follow Watt’s example in constructing his steam-engine, namely, to combine the plans and discoveries of other inventors in a machine of his own, and so achieve a more complete success.

Stephenson was now very well regarded at the colliery for the improvements he had made there. He brought the matter of building a new “Traveling Engine,” as he called it, to the attention of the lessees of the mine in 1813. Lord Ravensworth, the principal partner, formed a favorable opinion of Stephenson’s plans, and agreed to supply him with the funds necessary to build a locomotive.

With his support Stephenson went to work to choose his tools and workmen. He had to devise and make many of the tools he needed, and to train his men specially for this business. He built his first engine in the workshops at the West Moor Mine. It followed to some extent the model of Blenkinsop’s engine. It had a cylindrical boiler, eight feet long and thirty-four inches in diameter, with an internal flue tube passing through it. The engine had two vertical cylinders and worked the propelling gear with cross-heads and connecting-rods. The power of the two cylinders was carried by means of spur-wheels, which continued the motive power to the wheels that supported the engine on the rails. The engine was simply mounted on a wooden frame that was supported on four wheels. These wheels were smooth, as Stephenson was convinced that smooth wheels would run properly on an edge-rail.

This engine, christened the “Blutcher,” and taking about ten months to build, was tried on the Killingworth Railway on July 25, 1814. It proved to be the most successful working engine that had yet been built, and would pull eight loaded wagons of about thirty tons’ weight up a slight grade at the rate of four miles an hour. For some time it was used daily at the colliery.

But the “Blutcher” was after all a very clumsy machine. The engine had no springs, and its movement was a series of jolts, that injured the rails and shook the machinery apart. The important parts of the machinery were huddled together, and caused friction, and the cog-wheels soon became badly worn. Moreover the engine moved scarcely faster than a horse’s walk, and the expense of running it was very little less than the cost of horse-power. Stephenson saw that he must in some way increase the power of his engine if he was to provide a new motive power for the mines.

In this first engine the steam had been allowed to escape into the air with a loud, hissing noise, which frightened horses and cattle, and was generally regarded as a nuisance. Stephenson thought that if he could carry this steam, after it had done its work in the cylinders, into the chimney by means of a small pipe, and allow it to escape in a vertical direction, its velocity would be added to the smoke from the fire, or the rising current of air in the chimney, and would in that way increase the draught, and as a result the intensity of combustion in the furnace. He tried this experiment, and found his conjecture correct; the blast stimulated combustion, consequently the capability of the boiler to generate steam was greatly increased, and the power of the engine increased in the same proportion. No extra weight was added to the machine. The invention of this steam blast was almost the turning point in the history of the locomotive. Without it the engine would have been too clumsy and slow for practical use, but with it the greatest possibilities of use appeared.

Encouraged by the success of his steam blast Stephenson started to build a second locomotive. In this he planned an entire change in mechanical construction, his principal objects being the use of as few parts as possible, and the most direct possible application of power to the wheels. He took out a patent for this engine on February 28, 1815. This locomotive had two vertical cylinders that communicated directly with each pair of the four wheels that supported the engine, by means of a cross-head and a pair of connecting-rods. “Ball and socket” joints were used to make the union between the ends of the cross-heads where they united with the connecting-rods, and between the rods and the crank-pins attached to each driving-wheel. The mechanical skill of his workmen was not equal to the forging of all the necessary parts as Stephenson had devised them, and he was obliged to make use of substitutes which did not always work smoothly, but he finally succeeded in completing a locomotive which was a vast improvement on all earlier ones, and that was notable for the simple and direct communication between the cylinders and the wheels, and the added power gained by using the waste steam in the steam blast. This second locomotive of Stephenson’s was in the main the model for all those built for a considerable time.