This first railway locomotive was finished and tried upon the Merthyr tram-road on the 21st of February, 1804. It had a cylindrical wrought-iron boiler with flat ends. The furnace and flue were inside the boiler, the flue returning, having its exit at the same end at which it entered, so as to increase the heating surface. The cylinder, 4-3/4 in. in diameter, was placed horizontally in the end of the boiler, and the waste steam was thrown into the stack. The wheels were worked in the same manner as in the carriage engine already described; and a fly-wheel was added on one side, to secure a continuous rotary motion at the end of each stroke of the piston. The pressure of the steam was about 40 lbs. on the inch. The engine ran upon four wheels, coupled by cog-wheels, and those who remember the engine say that the four wheels were smooth. [Illustration: TREVITHICK'S HIGH-PRESSURE TRAM-ENGINE.] On the first trial, this engine drew for a distance of nine miles ten tons of bar iron, together with the necessary carriages, water, and fuel, at the rate of five and a half miles an hour. Rees Jones, an old engine-fitter, who helped to erect the engine, and was alive in 1858, gave Mr. Menelaus the following account of its performances: "When the engine was finished, she was used for bringing down metal from the old forge. She worked very well; but frequently, from her weight, broke the tram-plates, and also the hooks between the trams. After working for some time in this way, she took a journey of iron from Pen-y-darran down the Basin Road, upon which road she was intended to work. On the journey she broke a great many of the tram-plates; and, before reaching the Basin, she ran off the road, and was brought back to Pen-y-darran by horses. The engine was never used as a locomotive after this; but she was used as a stationary engine, and worked in this way for several years." So far as the locomotive was concerned it was a remarkable success. The defect lay not in the engine so much as in the road. This was formed of plate-rails of cast iron, with a guiding flange upon the rail instead of on the engine wheels, as in the modern locomotive. The rails were also of a very weak form, considering the quantity of iron in them; and, though they were sufficient to bear the loaded wagons mounted upon small wheels, as ordinarily drawn along them by horses, they were found quite insufficient to bear the weight of Trevithick's engine. To relay the road of sufficient strength would have involved a heavy outlay, which the owners were unwilling to incur, not yet perceiving the advantage, in an economical point of view, of employing engine in lieu of horse power. The locomotive was accordingly taken off the road, and the experiment, successful though it had been, was brought to an end.