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
travelling 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 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.GEORGE
STEPHENSON.
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.
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