CHAPTER VI
TREVITHICK'S ENGINE
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
