WHILE these propositions were developing, one Richard Trevithick, a foreman in a Cornish tin-mine, prompted, no doubt, by seeing the model engine which Murdoch had constructed, determined to build a carriage to run on common roads, and a Mr. Vivian joined him in the enterprise. They took out a patent in 1802. A description of this machine will not be uninteresting to our readers:
This steam-carriage resembled a stage-coach, and was upon four wheels. It had one horizontal cylinder, which, together with the boiler and 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 derived its motion. It is worthy of note that the steam-racks and force-pumps, as also the bellows used in generating combustion, were worked off the same crank-axle.
This was the first successful high-pressure engine constructed on the principle of moving a piston, by the elasticity of steam, against the pressure of the atmosphere, and without a vacuum. Such an engine had been described by Leopold, though in his apparatus the pressure acted only on one side of the pistols while in Trevithick's and Vivian's engine the piston was not only raised but likewise depressed by the steam. This was original with them, and of great merit.
This kind of carriage on common roads was tolerably successful. It was exhibited at the city of London, and attracted great crowds to witness its performance; and it drew behind it a carriage filled with passengers. But it soon became obvious that the roads in England were too rough and uneven for the successful use of such machines, and it was soon after abandoned by Trevithick as a practical failure.
Trevithick next turned his attention to the invention of a steam-carriage or locomotive, to run upon the tram-roads then in general use in England; and in 1804 he commenced his machine; in the same year it was completed and tried upon the Merthyr-Tydvil Railway, in South Wales. On this occasion it succeeded in drawing after it several wagons containing ten tons of bar-iron, at the rate of five miles an hour. The boiler of this machine was cylindrical in form, flat at the ends, and constructed of cast-iron. The furnace and flues were inside the boiler, in which a single cylinder of eight inches in diameter and four feet six inch stroke was immersed upright. Although this locomotive, when tried upon the railroad as above stated, succeeded in drawing a considerable weight, and traveling at a fair speed, from other causes it proved like his first steam- carriage, a practical failure, and was soon abandoned. This experiment, however, may be considered as the first attempt to adapt the locomotive to service upon a railroad of which we have any written account.
The great difficulty and obstacle which at that early day did more than any thing else to retard the successful progress of the locomotive for railroad purposes, was the idea that, upon the smooth surface of a rail or iron plate then in use, the smooth surface of the driving-wheel would not have adhesive power to cause the engine to move forward, much less have a sufficient friction to enable the machine, not only to go ahead itself, but to draw a weight of carriages behind it To remedy this evil, Trevithick recommended, and caused to be placed upon the surface of the driving wheels of his machine, heads of bolts and numerous grooves, to produce the required adhesion. It proved successful, but produced a succession of jolts very trying. upon the cast-iron plates upon the roads upon which the experiments were tried, as well as upon the machine.
In 1811 a Mr. Blankensop, of Leeds, took out a patent for a machine and rail adapted to each other: a rack or toothed rail was to be laid down along one side of the track, into which a tooth- wheel of his locomotive worked. The boiler of his engine was supported by a carriage upon four wheels without teeth, and resting immediately on the axles These were entirely independent of the working- parts of the engine, and merely supported its weight, the progress being effected by the motion of the cogged wheels working on the cogged rail. This engine began running on the railroad from the Middleton collieries to the town of Leeds, about three and a quarter miles, on the 12th of August, 1812. For a number of years it was a permanent object of curiosity, and was visited by crowds of strangers from all parts. These engines (for several were afterward constructed) drew after them thirty coal-cars, loaded, at a speed of three and a quarter miles per hour, and were in use for many years, and may justly be considered as the first instance of the employment of locomotive power for commercial purposes.
Another curious experiment was tried in 1812, to overcome the want of friction upon the road and increase the power of the engine. A Sir. Chapman, of Newcastle, took out a patent for this invention. The plan was a chain stretched from one end of the road to the other. The chain was passed once round a grooved barrel-wheel under the centre of the engine, so that, when the wheels turned, the locomotive would, as it were, drag itself along the railway. The experiment was tried with an engine constructed for the purpose on the Heaton Railway, near Newcastle, but it was so clumsy in its action that it was soon abandoned.
But the most remarkable, extravagant, and amusing experiment of all, and one which must bring to the countenance of our readers at the present day a smile, was the one adopted by a Mr. Brunton, of the Butterby Works, Derbyshire, in 1813, who took out a patent for a machine which was to go upon legs like a horse. This contrivance had two legs attached to the back part, which, being alternately moved by the engine, pushed it before them. These legs, or propellers, imitated the legs of a man or the fore-legs of a horse, with joints, and when worked by the machine alternately lifted and pressed against the ground or road, propelling the engine forward, as a man shoves a boat ahead by pressing with a pole against the bottom of a river.
This contrivance was so singular and ingenious that we cannot refrain from giving a description of it, taken from a very interesting work upon road-making, by W. M. Gillespie.
The legs are indicated by H and F and H As f. H represents the hip- joint, IR and P the knee-joints, A and a the ankle-joints, and F and f the feet. We will first examine the action of the front leg. The knee, Id, is attached to the end of a piston-rod, which the steam drives backward and forward in the horizontal cylinder, C:. When the piston is driven outward, it presses the leg K F against the ground, and thus propels the engine forward, as a man shoves a boat ahead by pressing with a pole against the bottom of a river. As the engine advances, the leg straightens, the point H is carried forward, and the extremity, M, of the bent lever H M, is raised. A cord, M S. being attached to S. the shin of the leg, the motion of the lever tightens the cord, and finally raises the foot from the ground, and prepares it to take a fresh step where the reversed action of the piston has lowered it again. The action of the other leg is precisely similar, but motion communicated to it from the first one. Just above the knee of the front leg, at X, is attached a rod, on which is a toothed rack, R. Working in it is a cog-wheel, which enters also a second rack, el, below it, which is connected by a second rod with point X of the other leg. When the piston is driven out and pushes the engine from the knee, the rack R is drawn backward, and turns the cog- wheel, which then draws the lower rack i) forward, and operates on the hind leg precisely as the piston-rod does on the front one, and thus the legs take alternate steps, and walk on with the engine.
This locomotive or " mechanical traveller," as it was termed by its inventor, moved on a railway at the rate of two and a half miles per hour, with the tractive force of four horses. Mr. Brunton's machine, however, never got beyond the experimental state, for, on one of its trials, it unhappily blew up, killing and wounding several of the bystanders, was never repaired, but laid aside as one of the failures of the times.
These experiments, though failures in their results, were followed up by a Mr. Blackett, of Wylam, whose persevering efforts paved the way for the future labors of George Stephenson.
To make his experiments Mr. Blackett ordered one of the locomotives of the Trevithick patent, and also employed rack - rails and tooth driving - wheels like Blankensop's, and had his road altered for the occasion. This engine was the most awkwardly-constructed machine imaginable. It had a single cylinder six inches in diameter, and a flywheel working on one side to carry the cranks over the dead-points. The boiler was of cast iron, and the weight of the whole was about six tons; a wooden frame was supported by four pairs of wheels, and a barrel of water placed upon another frame sustained by two pairs of wheels served as a tender. When all was ready, the word was given to go ahead, but the engine would not move an inch; when it was finally set in motion, it flew to pieces, and the workmen and spectators, with Mr. Blackett at their head, scattered and fled in every direction ! The machine, or what was left of it, was taken off the road, and afterward a portion of it was used as a pump at one of the mines.
Mr. Blackett was not, however, discouraged. His next experiment was an engine with a single eight-inch cylinder, which was fitted with a flywheel, the driving wheel on one side being cogged in order to enable it to travel on the rack-rail. This engine proved more successful than its predecessors, and, although it was clumsy and unsightly, it was capable of drawing eight or nine wagons loaded with coal to the shipping-point at Lemington; its weight, however, was too great for the road, and the cast-iron rails were continually breaking. Its work was by no means successful. It crept along at a snail's pace, sometimes taking six hours to go five miles to the landing-place. It was continually getting off the track, and there it would stick. Horses would then have to be sent out to pull it on the track. The engine often broke down; its pumps, plugs, and cranks would get wrong, then the horses again would be needed to drag the machine back to the shop. In fact, it at last got so cranky that the horses were frequently sent out to follow the engine to be in readiness to draw it along when it gave out. At last it was abandoned.
Notwithstanding the repeated failures, and the amount of money expended on these experiments, Mr Blackett persevered. In 1813 he made an experiment with a frame upon four wheels, to determine the much disputed point, the adhesive power of a smooth-surfaced driving wheel upon a smooth- surfaced rail. Six men were placed upon this frame, which was fitted up with a windlass attached by gearing to the several wheels. When the men worked the windlass, the adhesion was found sufficient to enable them to propel the machine without slipping. This experiment settled the difficulty which was always thought to be in the way of the successful use of the locomotive upon the smooth surface of a railroad with smooth-surfaced driving wheels, proving that rack- rails, tooth-wheels, endless chains, and legs, were useless requisites to the successful use of a locomotive with smooth- surfaced driving wheels upon a smooth-surfaced railroad-track, and drawing loaded wagons behind it.