In the following year, 1812, Messrs. William Chapman, of Durham, and E. W. Chapman. of Wellsend, Northumberland, took out a patent for " a method or methods of facilitating the means, and reducing the expense, of car riage on railways and other roads;" which they describe as chiefly consisting in the use of a chain, or other flexible and contmuous substance stretched along the road to be travelled, properly secured at each end, and at suitable intervals ; and in the application of this chain round, or partially round a grooved barrel or wheel, in such manner as not to slip when this grooved wheel, which is fixed upon, before, or behind a carriage containing the motive power, shall be put in motion by that power, so that by the revolution of the grooved barrel round its axis, either one way or the other, it shall necessarily draw the said carriage, and any others which may be attached to it, within its power of action. As the carriage containing the motive power, when thus loaded, may be too heavy in some instances for the existing iron or wooden rails, if it rested on four wheels cnly, Messrs. Chapman proposed to use six or eight wheels, in order that they might more freely move round curves in the road, and that the weight might be more distributed thereon ; the pressure being thus reduced upon each bearing point, in the inverse proportion of the number of wheels. The means adopted by the patentees for carrying their invention into effect, are described at consi derable 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 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, and which we propose to describe in the course of this article. We also remark, although it is of tittle moment, that the specification contains the first proposi tion 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 ver tical cylinders, fixed on either side of the boner. The motion of the piston rods actuated two vibrating beams, to which were appended two connecting rods, whose lower extremities worked two revolving clinks, 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 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 tile friction was equal to the drawing forward the train of eighteen waggons, after they were fairly in motion, it did not overcome their vie inertia until after a con siderable slipping of the wheels of the carriage.
We have introduced this notice of the earliest experiment made with the engine of the Messrs. Chapman, because it exemplifies, in the clearest manner, that precise inclination of the plane upon which the smooth wheels of a carriage, bearing a certain weight, will slip round, without advancing the machine. It also proves the necessity in such cases of increasing the friction of the opposing surfaces, either by augmenting the weight, or by some contrivance resembling those suggested by Trevithick in his specifications, which Dr. Lardner repeatedly in the course of his work treats as an absurd attempt to remedy an "imaginary difficulty." From all the information that we can glean in tracing out the early history of locomotion, this remarkable circumstance constantly presents itaelf,—that when Trevithick's carriages with smooth wheels were employed upon levels, or slightly inclined planes, invidious comparisons with others having cogs were made against the former, because, as was asserted, they slipped and could not ascend such acclivities as the latter ; and this, notwithstanding Trevithick first suggested by his " cross grooves and fittings to railroads" the very principle of the cogs, in a less objectionable form, and " all other appliances to boot" of the engine and boiler, contained in the said locomotive! Thus Trevithick lost many orders, and they were given to those who adopted all the essentials of hii plans, without acknowledgment, and employed them as the basis of their structures.
And when, after the lapse of years, it was found out by these gentlemen that smooth wheels had sufficient " bite " of the rail in most circumstances, they made that fact appear to be their own discovery ; notwithstanding it is stated in Trevithick's specification of 1802, and was confirmed by his practice ; which practice they at first condemned with one general voice ; and when, at last, they were compelled to practise it also, they endeavoured to make it appear as vastly superior to Trevithick's mode of surrounding his wheels " with heads of nails, bolts, and claws," which he never used at all ! These ungenerous pro ceedings against the most eminent mechanic of his time appear to have been going on unchecked from 1802 up to the present time, 1836. The only way we have of accounting for this circumstance is, that Trevithick was engaged during many years of his patent right in constructing his high-pressure engines and pumps for recovering the drowned mines of Peru, which undertaking he afterwards personally directed, and succeeded in accomplishing, to the astonish ment of the Peruvians. He was subsequently appointed engineer to the royal mint at Lima; and on his arrival at South America, lie was received with such enthusiastic gratitude, that the lord warden proposed to " erect his statue in silver." The earth now covers the mortal remains of this eminent man ; but his memory will never die : for, to use the words of Mr. Gordon, he has left behind him "a name as inseparably connected with high-pressure steam and locomotion, as that of James Watt with the condensing engine and rotary movement." 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 lie 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 • 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. On inspecting the drawing, it will be seen that 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 u direction parailel 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, 1 23, 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 1 2 3; the sliding-rack, acting on the toothed wheel, causes the other sliding-rod to move in the contrary direction, and with it the leg de. Whenever, therefore, the piston is at the extremity 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 a ful crum or 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 at ff, passing over friction sheaves, movable in one direction only, by a ratchet and catch, worked by the motion of the engine. The feet are described of various forms in the specification, the great object being to prevent them from injuring the road, and to obtain a firm footing, that no jerks should take place at the return of the st oke, when the action of the engine came upon them ; for this purpose they were made broad, with short spikes to lay hold of the ground.