The means adopted by the patentees for carrying their invention into effect, are described at considerable length, with explanatory drawings, in their specification; but as Mr. Wood informs us that the application of it failed at the Heaton Colliery, where it was for a time put into practical operation, and as the details of it would occupy too large a space in our pages, if inserted, we shall refer the reader to the enrolled document for them. The cause of the failure just mentioned is stated to have been owing to the waste of power arising from the excessive friction of the chain. There are one or two incidental observations in the specification which ought not perhaps to pass unnoticed. Allusion is made to the possibility of employing inflammable gas as the motive power, which, most of our readers are aware, was a few years ago carried into effect by the ingenious Samuel Brown. We also remark, although it is of little moment, that the specification contains the first proposition we have met with for employing the common winnowing machine to force a current of air under the fire-place. The annexed engraving exhibits an elevation of one of the locomotive engines of Messrs. Chapman, which was employed on the Heaton Colliery. The boiler consists of a large cylinder, of the Trevithick kind, with the furnace and a double or return flue passing through it to the chimney, situate on one side of the fire door; opposite to which is a chest containing the fuel of supply.
The steam chamber is a large vertical cylinder, from which proceeds laterally a pipe to conduct the steam to two vertical cylinders, fixed on either side of the boiler. The motion of the piston rods actuated two vibrating beams, to which were appended two connecting rods, whose lower extremities worked two revolving cranks, carrying on their axis, spur geer, which, through the medium of a train of toothed wheels, shown, gave simultaneous motion to all the running wheels. The weight of this engine, with its water and fuel, we are informed was six tons; and it was set to work in December 1812, upon the railway leading from Mr. J. G. Lambton's collieries to the river Wear. It drew after it 18 loaded coal waggons, weighing 54 tons, up a gentle ascent rising 5/16 of an inch to a yard (or 46 feet in a mile) at the rate of four miles an hour. The power of the engine was applied to the running wheels as already described; and it was found-that their resistance to slipping upon the rails was the utmost power it could exert in drawing waggons after it, which in this instance was carried to the extreme; for although the friction was equal to the drawing forward the train of eighteen waggons, after they were fairly in motion, it did not overcome their vis inertia until after a considerable slipping of the wheels of the carriage.
We now come to the description of a machine of great singularity, and which strongly attests the ingenuity of the contriver, Mr. William Brunton, of the Butterly Iron works, in Derbyshire, and for which he took out patents. It consists in a curious combination of levers, the action of which nearly resembles that of the legs of a man in walking, whose feet are alternately made to press against the ground of the road or railway, and in such a manner as to adapt themselves to the various inclinations or inequalities of the surface. The following engraving represents this engine, which the inventor called his "mechanical traveller." The boiler is nearly similar to that which we last described. The cylinder a is placed on one side of the boiler; the piston rod is projected out behind horizontally, and is attached to the leg a b at a, and to the reciprocating jointed bent lever above; at the lower extremity of the leg a b feet are attached by a joint at b; these feet lay a firmer hold on the ground, being furnished with short prongs, which prevent them from slipping; and are sufficiently broad to prevent their injuring the road.
When the piston rod is projected out from the cylinder, it will tend to push the end of the lever, or leg a, from it, in a direction parallel to the line of the cylinder; but, as the leg a b is prevented from moving backwards by the end b being firmly fixed upon the ground, the reaction is thrown upon the carriage, and a progressive motion given to it, and this will be continued to the end of the stroke. Upon the first reciprocating lever is fixed at 1, a rod 12 3 sliding horizontally backwards and forwards upon the top of the boiler; from 2 to 3 it is furnished with teeth, which work into a cog-wheel, lying horizontally; on the opposite side of this cog-wheel a sliding rack is fixed similar to 1 2 3, which, as the cog-wheel is turned round by the sliding rack 2 3, is also moved backwards and forwards. The end of this sliding rod is fixed upon the other reciprocating lever of the leg d e at 4. When, therefore, the sliding rack is moved forwards in the direction 3 2 1, by the progressive motion of the engine, and when the piston rod is at the farthest extremity of the stroke, the leg d e will be brought close to the engine; the piston is then made to return in the opposite direction, moving with it the leg a b, and also the sliding rack 12 3; the sliding rack acting on the tooth wheel causes the other sliding rod to move in the opposite direction, and with it the leg d e.
Whenever, therefore, the piston is at the end of the stroke, and one of the legs is no longer of use to propel the engine forward, the other, immediately on the motion of the piston being changed, is ready, in its turn, to act as an abutment for the action of the moving power to secure the continued progressive motion of the engine. The feet are raised from the ground during the return of the legs to the engine, by straps of leather or rope fastened to the legs atff, passing over friction sheaves, movable in one direction only, by a ratchet and catch, worked by the motion of the engine.