The idea was next taken up by Murdock’s pupil, Richard Trevithick, who resolved on building a steam-carriage adapted for common roads as well as railways. He took out a patent to secure the right of his invention in 1802. Andrew Vivian, his cousin, joined with him in the patent—Vivian finding the money, and Trevithick the brains. The steam-carriage built on this patent presented the appearance of an ordinary stage-coach on four wheels. The engine had one horizontal cylinder, which, together with the boiler and the furnace-box, was placed in the rear of the hind axle. The motion of the piston was transmitted to a separate crank-axle, from which, through the medium of spur-gear, the axle of the driving-wheel (which was mounted with a fly-wheel) derived its motion. The steam-cocks and the force-pump, as also the bellows used for the purpose of quickening combustion in the furnace, were worked off the same crank-axle. John Petherick, of Camborne, has related that he remembers this first English steam-coach passing along the principal street of his native town. Considerable difficulty was experienced in keeping up the pressure of steam; but when there was pressure enough, Trevithick would call upon the people to “jump up,” so as to create a load upon the engine. It was soon covered with men attracted by the novelty, nor did their number seem to make any difference in the speed of the engine so long as there was steam enough; but it was constantly running short, and the horizontal bellows failed to keep it up. This road-locomotive of Trevithick’s was one of the first high-pressure working engines constructed on the principle of moving a piston by the elasticity of steam against the pressure only of the atmosphere. Such an engine had been described by Leopold, though in his apparatus it was proposed that the pressure should act only on one side of the piston. In Trevithick’s engine the piston was not only raised, but was also depressed by the action of the steam, being in this respect an entirely original invention, and of great merit. The steam was admitted from the boiler under the piston moving in a cylinder, impelling it upward. When the motion had reached its limit, the communication between the piston and the under side was shut off, and the steam allowed to escape into the atmosphere. A passage being then opened between the boiler and the upper side of the piston, which was pressed downwards, the steam was again allowed to escape as before. Thus the power of the engine was equal to the difference between the pressure of the atmosphere and the elasticity of the steam in the boiler.