EARLY HISTORY OF THE LOCOMOTIVE--GEORGE STEPHENSON BEGINS ITS
IMPROVEMENT.
The rapid increase in the coal-trade of the Tyne about the beginning of
the present century had the effect of stimulating the ingenuity of
mechanics, and encouraging them to devise improved methods of
transporting the coal from the pits to the shipping places. From our
introductory chapter, it will have been observed that the improvements
which had thus far been effected were confined almost entirely to the
road. The railway waggons still continued to be drawn by horses. By
improving and flattening the tramway, considerable economy in horse-power
had indeed been secured; but unless some more effective method of
mechanical traction could be devised, it was clear that railway
improvement had almost reached its limits.
Many expedients had been tried with this object. One of the earliest was
that of hoisting sails upon the waggons, and driving them along the
waggon-way, as a ship is driven through the water by the wind. This
method seems to have been employed by Sir Humphrey Mackworth, an
ingenious coal-miner at Neath in Glamorganshire, about the end of the
seventeenth century.
After having been lost sight of for more than a century, the same plan of
impelling carriages was revived by Richard Lovell Edgworth, with the
addition of a portable railway, since revived also, in Boydell's patent.
But although Mr. Edgworth devoted himself to the subject for many years,
he failed in securing the adoption of his sailing carriage. It is indeed
quite clear that a power so uncertain as wind could never be relied on
for ordinary traffic, and Mr. Edgworth's project was consequently left to
repose in the limbo of the Patent Office, with thousands of other equally
useless though ingenious contrivances.
A much more favourite scheme was the application of steam power for the
purpose of carriage traction. Savery, the inventor of the working
steam-engine, was the first to propose its employment to propel vehicles
along the common roads; and in 1759 Dr. Robison, then a young man
studying at Glasgow College, threw out the same idea to his friend James
Watt; but the scheme was not matured.
[Picture: Cugnot's Engine]
The first locomotive steam-carriage was built at Paris by the French
engineer Cugnot, a native of Lorraine. It is said to have been invented
for the purpose of dragging cannon into the field independent of horses.
The original model of this machine was made in 1763. Count Saxe was so
much pleased with it, that on his recommendation a full-sized engine was
constructed at the cost of the French monarch; and in 1769 it was tried
in the presence of the Duc de Choiseul, Minister of War, General
Gribeauval, and other officers. At one of the experiments it ran with
such force as to knock down a wall in its way. But the new vehicle,
loaded with four persons, could not travel faster than two and a half
miles an hour. The boiler was insufficient in size, and it could only
work for about fifteen minutes; after which it was necessary to wait
until the steam had again risen to a sufficient pressure. To remedy this
defect, Cugnot constructed a new machine in 1770, the working of which
was more satisfactory. It was composed of two parts--the fore part
consisting of a small steam-engine, formed of a round copper boiler, with
a furnace inside, provided with two small chimneys and two single-acting
brass steam cylinders, whose pistons acted alternately upon the single
driving-wheel. The hinder part consisted merely of a rude carriage on
two wheels to carry the load, furnished with a seat in front for the
conductor. This engine was tried in the streets of Paris; but when
passing near where the Madeleine now stands, it overbalanced itself on
turning a corner, and fell over with a crash; after which, its employment
being thought dangerous, it was locked up in the arsenal to prevent
further mischief. The machine is, however, still to be seen in the
collection of the Conservatoire des Arts et Metiers at Paris. It has
very much the look of a long brewer's cart, with the addition of the
circular boiler hung on at one end. Rough though it looks, it was a
highly creditable piece of work, considering the period at which it was
executed; and as the first actual machine constructed for the purpose of
travelling on ordinary roads by the power of steam, it is certainly a
most curious and interesting mechanical relic, well worthy of
preservation.
But though Cugnot's road locomotive remained locked up from public sight,
the subject was not dead; for we find inventors employing themselves from
time to time in attempting to solve the problem of steam locomotion in
places far remote from Paris. The idea had taken root in the minds of
inventors, and was striving to grow into a reality. Thus Oliver Evans,
the American, invented a steam carriage in 1772 to travel on common
roads; in 1787 he obtained from the State of Maryland an exclusive right
to make and use steam-carriages, but his invention never came into use.
Then, in 1784, William Symington, one of the early inventors of the
steamboat, was similarly occupied in Scotland in endeavouring to develop
the latent powers of the steam-carriage. He had a working model of one
constructed, which he exhibited in 1786 to the professors of Edinburgh
College; but the state of the Scotch roads was then so bad that he found
it impracticable to proceed further with his scheme, which he shortly
after abandoned in favour of steam navigation.
[Picture: Section of Murdock's Model]
The same year in which Symington was occupied upon his steam-carriage,
William Murdock, the friend and assistant of Watt, constructed his model
of a locomotive at the opposite end of the island--at Redruth in
Cornwall. His model was of small dimensions, standing little more than a
foot high; and it was until recently in the possession of the son of the
inventor, at whose house we saw it a few years ago. The annexed section
will give an idea of the arrangements of this machine.
It acted on the high-pressure principle, and, like Cugnot's engine, ran
upon three wheels, the boiler being heated by a spirit-lamp. Small
though the machine was, it went so fast on one occasion that it fairly
outran its inventor. It seems that one night after returning from his
duties at the Redruth mine, Murdock determined to try the working of his
model locomotive. For this purpose he had recourse to the walk leading
to the church, about a mile from the town. It was rather narrow, and was
bounded on each side by high hedges. The night was dark, and Murdock set
out alone to try his experiment. Having lit his lamp, the water boiled
speedily, and off started the engine with the inventor after it. He soon
heard distant shouts of terror. It was too dark to perceive objects; but
he found, on following up the machine, that the cries proceeded from the
worthy pastor of the parish, who, going towards the town, was met on this
lonely road by the hissing and fiery little monster, which he
subsequently declared he had taken to be the Evil One _in propria
persona_. No further steps were, however, taken by Murdock to embody his
idea of a locomotive carriage in a more practical form.
The idea was next taken up by Murdock's pupil, Richard Trevithick, who
resolved on building a steam-carriage adapted for common roads as well as
railways. He took out a patent to secure the right of his invention in
1802. Andrew Vivian, his cousin, joined with him in the patent--Vivian
finding the money, and Trevithick the brains. The steam-carriage built
on this patent presented the appearance of an ordinary stage-coach on
four wheels. The engine had one horizontal cylinder, which, together
with the boiler and the 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 (which was mounted with a fly-wheel) derived its motion.
The steam-cocks and the force-pump, as also the bellows used for the
purpose of quickening combustion in the furnace, were worked off the same
crank-axle.
John Petherick, of Camborne, has related that he remembers this first
English steam-coach passing along the principal street of his native
town. Considerable difficulty was experienced in keeping up the pressure
of steam; but when there was pressure enough, Trevithick would call upon
the people to "jump up," so as to create a load upon the engine. It was
soon covered with men attracted by the novelty, nor did their number seem
to make any difference in the speed of the engine so long as there was
steam enough; but it was constantly running short, and the horizontal
bellows failed to keep it up.
This road-locomotive of Trevithick's was one of the first high-pressure
working engines constructed on the principle of moving a piston by the
elasticity of steam against the pressure only of the atmosphere. Such an
engine had been described by Leopold, though in his apparatus it was
proposed that the pressure should act only on one side of the piston. In
Trevithick's engine the piston was not only raised, but was also
depressed by the action of the steam, being in this respect an entirely
original invention, and of great merit. The steam was admitted from the
boiler under the piston moving in a cylinder, impelling it upward. When
the motion had reached its limit, the communication between the piston
and the under side was shut off, and the steam allowed to escape into the
atmosphere. A passage being then opened between the boiler and the upper
side of the piston, which was pressed downwards, the steam was again
allowed to escape as before. Thus the power of the engine was equal to
the difference between the pressure of the atmosphere and the elasticity
of the steam in the boiler.
This steam-carriage excited considerable interest in the remote district
near the Land's End where it had been erected. Being so far removed from
the great movements and enterprise of the commercial world, Trevithick
and Vivian determined upon exhibiting their machine in the metropolis.
They accordingly set out with it to Plymouth, whence it was conveyed by
sea to London.
The carriage safely reached the metropolis, and excited much public
interest. It also attracted the notice of scientific men, amongst others
of Mr. Davies Gilbert, President of the Royal Society, and Sir Humphry
Davy, both Cornishmen like Trevithick, who went to see the private
performances of the engine, and were greatly pleased with it. Writing to
a Cornish friend shortly after its arrival in town, Sir Humphry said: "I
shall soon hope to hear that the roads of England are the haunts of
Captain Trevithick's dragons--a characteristic name." The machine was
afterwards publicly exhibited in an enclosed piece of ground near Euston
Square, where the London and North-Western Station now stands, and it
dragged behind it a wheel-carriage full of passengers. On the second day
of the performance, crowds flocked to see it; but Trevithick, in one of
his odd freaks, shut up the place, and shortly after removed the engine.
It is, however, probable that the inventor came to the conclusion that
the state of the roads at that time was such as to preclude its coming
into general use for purposes of ordinary traffic.
While the steam-carriage was being exhibited, a gentleman was laying
heavy wagers as to the weight which could be hauled by a single horse on
the Wandsworth and Croydon iron tramway; and the number and weight of
waggons drawn by the horse were something surprising. Trevithick very
probably put the two things together--the steam-horse and the
iron-way--and kept the performance in mind when he proceeded to construct
his second or railway locomotive. The idea was not, however, entirely
new to him; for, although his first engine had been constructed with a
view to its employment upon common roads, the specification of his patent
distinctly alludes to the application of his engine to travelling on
railroads. Having been employed at the iron-works of Pen-y-darran, in
South Wales, to erect a forge engine for the Company, a convenient
opportunity presented itself, on the completion of this work, for
carrying out his design of a locomotive to haul the minerals along the
Pen-y-darran tramway. Such an engine was erected by him in 1803, in the
blacksmiths' shop at the Company's works, and it was finished and ready
for trial before the end of the year.
The boiler of this second engine was cylindrical in form, flat at the
ends, and made of wrought iron. The furnace and flue were inside the
boiler, within which the single cylinder, eight inches in diameter and
four feet six inches stroke, was placed horizontally. As in the first
engine, the motion of the wheels was produced by spur gear, to which was
also added a fly-wheel on one side, to secure a rotatory motion in the
crank at the end of each stroke of the piston in the single cylinder.
The waste steam was thrown into the chimney through a tube inserted into
it at right angles; but it will be obvious that this arrangement was not
calculated to produce any result in the way of a steam-blast in the
chimney. In fact, the waste steam seems to have been turned into the
chimney in order to get rid of the nuisance caused by throwing the jet
directly into the air. Trevithick was here hovering on the verge of a
great discovery; but that he was not aware of the action of the blast in
contributing to increase the draught and thus quicken combustion, is
clear from the fact that he employed bellows for this special purpose;
and at a much later date (1815) he took out a patent which included a
method of urging the fire by means of fanners. {70}
[Picture: Trevithick's High Pressure Tram-Engine]
At the first trial of this engine it succeeded in dragging after it
several waggons, containing ten tons of bar-iron, at the rate of about
five miles an hour. Rees Jones, who worked at the fitting of the engine,
and remembers its performances, says, "She was used for bringing down
metal from the furnaces to the Old Forge. She worked very well; but
frequently, from her weight, broke the tram-plates and the hooks between
the trams. After working for some time in this way, she took a load of
iron from Pen-y-darran down the Basin-road, upon which road she was
intended to work. On the journey she broke a great many of the
tram-plates, and before reaching the basin ran off the road, and had to
be brought back to Pen-y-darran by horses. The engine was never after
used as a locomotive." {71}
It seems to have been felt that unless the road were entirely
reconstructed so as to bear the heavy weight of the locomotive--so much
greater than that of the tram-waggons, to carry which the original rails
had been laid down--the regular employment of Trevithick's high-pressure
tram-engine was altogether impracticable; and as the owners of the works
were not prepared to incur so serious a cost, it was determined to take
the locomotive off the road, and employ it as an engine for other
purposes. It was accordingly dismounted, and used for some time after as
a pumping-engine, for which purpose it was found well adapted.
Trevithick himself seems from this time to have taken no further steps to
bring the locomotive into general use. We find him, shortly after,
engaged upon schemes of a more promising character, abandoning the engine
to other mechanical inventors, though little improvement was made in it
for several years. An imaginary difficulty seems to have tended, amongst
other obstacles, to prevent its adoption; viz., the idea that, if a heavy
weight were placed behind the engine, the "grip" or "bite" of its smooth
wheels upon the equally smooth iron rail, must necessarily be so slight
that they would whirl round upon it, and, consequently, that the machine
would not make progress. Hence Trevithick, in his patent, provided that
the periphery of the driving-wheels should be made rough by the
projection of bolts or cross-grooves, so that the adhesion of the wheels
to the road might be secured.
Following up the presumed necessity for a more effectual adhesion between
the wheels and the rails, Mr. Blenkinsop of Leeds, in 1811, took out a
patent for a racked or tooth-rail laid along one side of the road, into
which the toothed-wheel of his locomotive worked as pinions work into a
rack. The boiler of his engine was supported by a carriage with four
wheels without teeth, and rested immediately upon the axles. These
wheels were entirely independent of the working parts of the engine, and
therefore merely supported its weight upon the rails, the progress being
effected by means of the cogged-wheel working into the cogged-rail. The
engine had two cylinders, instead of one as in Trevithick's engine. The
invention of the double cylinder was due to Matthew Murray, of Leeds, one
of the best mechanical engineers of his time; Mr. Blenkinsop, who was not
a mechanic, having consulted him as to all the practical arrangements.
The connecting-rods gave the motion to two pinions by cranks at right
angles to each other; these pinions communicating the motion to the wheel
which worked into the cogged-rail.
Mr. Blenkinsop's engines began running on the railway from the Middleton
Collieries to Leeds, about 3.5 miles, on the 12th of August, 1812. They
continued for many years to be one of the principal curiosities of the
place, and were visited by strangers from all parts. In 1816, the Grand
Duke Nicholas (afterwards Emperor) of Russia observed the working of
Blenkinsop's locomotive with curious interest and admiration. An engine
dragged as many as thirty coal-waggons at a speed of about 3.25 miles per
hour. These engines continued for many years to be thus employed in the
haulage of coal, and furnished the first instance of the regular
employment of locomotive power for commercial purposes.
The Messrs. Chapman, of Newcastle, in 1812, endeavoured to overcome the
same fictitious difficulty of the want of adhesion between the wheel and
the rail, by patenting a locomotive to work along the road by means of a
chain stretched from one end of it to the other. This chain was passed
once round a grooved barrel-wheel under the centre of the engine: so
that, when the wheel turned, the locomotive, as it were, dragged itself
along the railway. An engine, constructed after this plan, was tried on
the Heaton Railway, near Newcastle; but it was so clumsy in its action,
there was so great a loss of power by friction, and it was found to be so
expensive and difficult to keep in repair, that it was soon abandoned.
Another remarkable expedient was adopted by Mr. Brunton, of the Butterley
Works, Derbyshire, who, in 1813, patented his Mechanical Traveller, to go
_upon legs_ working alternately like those of a horse. {73} But this
engine never got beyond the experimental state, for, at its very first
trial, the driver, to make sure of a good start, overloaded the
safety-valve, when the boiler burst and killed a number of the
bystanders, wounding many more. These, and other contrivances with the
same object, projected about the same time, show that invention was
actively at work, and that many minds were anxiously labouring to solve
the important problem of locomotive traction upon railways.
But the difficulties contended with by these early inventors, and the
step-by-step progress which they made, will probably be best illustrated
by the experiments conducted by Mr. Blackett, of Wylam, which are all the
more worthy of notice, as the persevering efforts of this gentleman in a
great measure paved the way for the labours of George Stephenson, who,
shortly after, took up the question of steam locomotion, and brought it
to a successful issue.
The Wylam waggon-way is one of the oldest in the north of England. Down
to the year 1807 it was formed of wooden spars or rails, laid down
between the colliery at Wylam--where old Robert Stephenson had
worked--and the village of Lemington, some four miles down the Tyne,
where the coals were loaded into keels or barges, and floated down past
Newcastle, to be shipped for London. Each chaldron-waggon had a man in
charge of it, and was originally drawn by one horse. The rate at which
the waggons were hauled was so slow that only two journeys were performed
by each man and horse in one day, and three on the day following. This
primitive waggon-way passed, as before stated, close in front of the
cottage in which George Stephenson was born; and one of the earliest
sights which met his infant eyes was this wooden tramroad worked by
horses.
Mr. Blackett was the first colliery owner in the North who took an active
interest in the locomotive. Having formed the acquaintance of Trevithick
in London, and inspected the performances of his engine, he determined to
repeat the Pen-y-darran experiment upon the Wylam waggon-way. He
accordingly obtained from Trevithick, in October, 1804, a plan of his
engine, provided with "friction-wheels," and employed Mr. John Whinfield,
of Pipewellgate, Gateshead, to construct it at his foundry there. The
engine was constructed under the superintendence of one John Steele, an
ingenious mechanic who had been in Wales, and worked under Trevithick in
fitting the engine at Pen-y-darran. When the Gateshead locomotive was
finished, a temporary way was laid down in the works, on which it was run
backwards and forwards many times. For some reason, however--it is said
because the engine was deemed too light for drawing the coal-trains--it
never left the works, but was dismounted from the wheels, and set to blow
the cupola of the foundry, in which service it long continued to be
employed.
Several years elapsed before Mr. Blackett took any further steps to carry
out his idea. The final abandonment of Trevithick's locomotive at
Pen-y-darran perhaps contributed to deter him from proceeding further;
but he had the wooden tramway taken up in 1808, and a plate-way of
cast-iron laid down instead--a single line furnished with sidings to
enable the laden waggons to pass the empty ones. The new iron road
proved so much smoother than the old wooden one, that a single horse,
instead of drawing one, was now enabled to draw two, or even three, laden
waggons.
Encouraged by the success of Mr. Blenkinsop's experiment at Leeds, Mr.
Blackett determined to follow his example; and in 1812 he ordered a
second engine, to work with a toothed driving-wheel upon a rack-rail.
This locomotive was constructed by Thomas Waters, of Gateshead, under the
superintendence of Jonathan Foster, Mr. Blackett's principal
engine-wright. It was a combination of Trevithick's and Blenkinsop's
engines; but it was of a more awkward construction than either. The
boiler was of cast-iron. The engine was provided with a single cylinder
six inches in diameter, with a fly-wheel working at one side to carry the
crank over the dead points. Jonathan Foster described it to the author
in 1854, as "a strange machine, with lots of pumps, cog-wheels, and
plugs, requiring constant attention while at work." The weight of the
whole was about six tons.
When finished, it was conveyed to Wylam on a waggon, and there mounted
upon a wooden frame supported by four pairs of wheels, which had been
constructed for its reception. A barrel of water, placed on another
frame upon wheels, was attached to it as a tender. After a great deal of
labour, the cumbrous machine was got upon the road. At first it would
not move an inch. Its maker, Tommy Waters, became impatient, and at
length enraged, and taking hold of the lever of the safety valve,
declared in his desperation, that "either _she_ or _he_ should go." At
length the machinery was set in motion, on which, as Jonathan Foster
described to the author "she flew all to pieces, and it was the biggest
wonder i' the world that we were not all blewn up." The incompetent and
useless engine was declared to be a failure; it was shortly after
dismounted and sold; and Mr. Blackett's praiseworthy efforts thus far
proved in vain.
He was still, however, desirous of testing the practicability of
employing locomotive power in working the coal down to Lemington, and he
determined on another trial. He accordingly directed his engine-wright
to proceed with the building of a third engine in the Wylam workshops.
This new locomotive had a single 8-inch cylinder, was provided with a
fly-wheel like its predecessor, and the driving-wheel was cogged on one
side to enable it to travel in the rack-rail laid along the road. This
engine proved more successful than the former one; and it was found
capable of dragging eight or nine loaded waggons, though at the rate of
little more than a mile an hour, from the colliery to the shipping-place.
It sometimes took six hours to perform the journey of five miles. Its
weight was found too great for the road, and the cast-iron plates were
constantly breaking. It was also very apt to get off the rack-rail, and
then it stood still. The driver was one day asked how he got on? "Get
on?" said he, "we don't get on; we only get off!" On such occasions,
horses had to be sent to drag the waggons as before, and others to haul
the engine back to the work-shops. It was constantly getting out of
order; its plugs, pumps, or cranks, got wrong; it was under repair as
often as at work; at length it became so cranky that the horses were
usually sent out after it to drag it when it gave up; and the workmen
generally declared it to be a "perfect plague." Mr. Blackett did not
obtain credit amongst his neighbours for these experiments. Many laughed
at his machines, regarding them only in the light of
crotchets,--frequently quoting the proverb that "a fool and his money are
soon parted." Others regarded them as absurd innovations on the
established method of hauling coal; and pronounced that they would "never
answer."
Notwithstanding, however, the comparative failure of this second
locomotive, Mr. Blackett persevered with his experiments. He was
zealously assisted by Jonathan Foster the engine-wright, and William
Hedley, the viewer of the colliery, a highly ingenious person, who proved
of great use in carrying out the experiments to a successful issue. One
of the chief causes of failure being the rack-rail, the idea occurred to
Mr. Hedley that it might be possible to secure adhesion enough between
the wheel and the rail by the mere weight of the engine, and he proceeded
to make a series of experiments for the purpose of determining this
problem. He had a frame placed on four wheels, and fitted up with
windlasses attached by gearing to the several wheels. The frame having
been properly weighted, six men were set to work the windlasses; when it
was found that the adhesion of the smooth wheels on the smooth rails was
quite sufficient to enable them to propel the machine without slipping.
Having found the proportion which the power bore to the weight, he
demonstrated by successive experiments that the weight of the engine
would of itself produce sufficient adhesion to enable it to draw upon a
smooth railroad the requisite number of waggons in all kinds of weather.
And thus was the fallacy which had heretofore prevailed on this subject
completely exploded, and it was satisfactorily proved that rack-rails,
toothed wheels, endless chains, and legs, were alike unnecessary for the
efficient traction of loaded waggons upon a moderately level road.
From this time forward considerably less difficulty was experienced in
working the coal trains upon the Wylam tramroad. At length the rack-rail
was dispensed with. The road was laid with heavier rails; the working of
the old engine was improved; and a new engine was shortly after built and
placed upon the road, still on eight wheels, driven by seven rack-wheels
working inside them--with a wrought-iron boiler through which the flue
was returned so as largely to increase the heating surface, and thus give
increased power to the engine.
[Picture: Improved Wylam Engine]
As may readily be imagined, the jets of steam from the piston, blowing
off into the air at high pressure while the engine was in motion, caused
considerable annoyance to horses passing along the Wylam road, at that
time a public highway. The nuisance was felt to be almost intolerable,
and a neighbouring gentleman threatened to have it put down. To diminish
the noise as much as possible, Mr. Blackett gave orders that so soon as
any horse, or horses, came in sight, the locomotive was to be stopped,
and the frightful blast of the engine thus suspended until the passing
animals had got out of hearing. Much interruption was thus caused to the
working of the railway, and it excited considerable dissatisfaction
amongst the workmen. The following plan was adopted to abate the
nuisance: a reservoir was provided immediately behind the chimney (as
shown in the preceding cut) into which the waste steam was thrown after
it had performed its office in the cylinder; and from this reservoir, the
steam gradually escaped into the atmosphere without noise.
While Mr. Blackett was thus experimenting and building locomotives at
Wylam, George Stephenson was anxiously studying the same subject at
Killingworth. He was no sooner appointed engine-wright of the collieries
than his attention was directed to the means of more economically hauling
the coal from the pits to the river-side. We have seen that one of the
first important improvements which he made, after being placed in charge
of the colliery machinery, was to apply the surplus power of a pumping
steam-engine, fixed underground, to drawing the coals out of the deeper
workings of the Killingworth mines,--by which he succeeded in effecting a
large reduction in the expenditure on manual and horse labour.
The coals, when brought above ground, had next to be laboriously dragged
by horses to the shipping staiths on the Tyne, several miles distant.
The adoption of a tramroad, it is true, had tended to facilitate their
transit. Nevertheless the haulage was both tedious and costly. With the
view of economising labour, Stephenson laid down inclined planes where
the nature of the ground would admit of this expedient. Thus, a train of
full waggons let down the incline by means of a rope running over wheels
laid along the tramroad, the other end of which was attached to a train
of empty waggons placed at the bottom of the parallel road on the same
incline, dragged them up by the simple power of gravity. But this
applied only to a comparatively small part of the road. An economical
method of working the coal trains, instead of by horses,--the keep of
which was at that time very costly, from the high price of corn,--was
still a great desideratum; and the best practical minds in the collieries
were actively engaged in the attempt to solve the problem.
In the first place Stephenson resolved to make himself thoroughly
acquainted with what had already been done. Mr. Blackett's engines were
working daily at Wylam, past the cottage where he had been born; and
thither he frequently went to inspect the improvements made by Mr.
Blackett from time to time both in the locomotive and in the plateway
along which it worked. Jonathan Foster informed us that, after one of
these visits, Stephenson declared to him his conviction that a much more
effective engine might be made, that should work more steadily and draw
the load more effectively.
He had also the advantage, about the same time, of seeing one of
Blenkinsop's Leeds engines, which was placed on the tramway leading from
the collieries of Kenton and Coxlodge, on the 2nd September, 1813. This
locomotive drew sixteen chaldron waggons containing an aggregate weight
of seventy tons, at the rate of about three miles an hour. George
Stephenson and several of the Killingworth men were amongst the crowd of
spectators that day; and after examining the engine and observing its
performances, he observed to his companions, that "he thought he could
make a better engine than that, to go upon legs." Probably he had heard
of the invention of Brunton, whose patent had by this time been
published, and proved the subject of much curious speculation in the
colliery districts. Certain it is, that, shortly after the inspection of
the Coxlodge engine, he contemplated the construction of a new
locomotive, which was to surpass all that had preceded it. He observed
that those engines which had been constructed up to this time, however
ingenious in their arrangements, had proved practical failures. Mr.
Blackett's was as yet both clumsy and expensive. Chapman's had been
removed from the Heaton tramway in 1812, and was regarded as a total
failure. And the Blenkinsop engine at Coxlodge was found very unsteady
and costly in its working; besides, it pulled the rails to pieces, the
entire strain being upon the rack-rail on one side of the road. The
boiler, however, having soon after blown up, there was an end of that
engine; and the colliery owners did not feel encouraged to try any
further experiment.
An efficient and economical working locomotive, therefore, still remained
to be invented; and to accomplish this object Mr. Stephenson now applied
himself. Profiting by what his predecessors had done, warned by their
failures and encouraged by their partial successes, he commenced his
labours. There was still wanting the man who should accomplish for the
locomotive what James Watt had done for the steam-engine, and combine in
a complete form the best points in the separate plans of others,
embodying with them such original inventions and adaptations of his own
as to entitle him to the merit of inventing the working locomotive, in
the same manner as James Watt is to be regarded as the inventor of the
working condensing-engine. This was the great work upon which George
Stephenson now entered, though probably without any adequate idea of the
ultimate importance of his labours to society and civilization.
He proceeded to bring the subject of constructing a "Travelling Engine,"
as he then denominated the locomotive, under the notice of the lessees of
the Killingworth Colliery, in the year 1813. Lord Ravensworth, the
principal partner, had already formed a very favourable opinion of the
new engine-wright, from the improvements which he had effected in the
colliery engines, both above and below ground; and, after considering the
matter, and hearing Stephenson's explanations, he authorised him to
proceed with the construction of a locomotive,--though his lordship was,
by some, called a fool for advancing money for such a purpose. "The
first locomotive that I made," said Stephenson, many years after, {82}
when speaking of his early career at a public meeting in Newcastle, "was
at Killingworth Colliery, and with Lord Ravensworth's money. Yes; Lord
Ravensworth and partners were the first to entrust me, thirty-two years
since, with money to make a locomotive engine. I said to my friends,
there was no limit to the speed of such an engine, if the works could be
made to stand."
Our engine-wright had, however, many obstacles to encounter before he
could get fairly to work with the erection of his locomotive. His chief
difficulty was in finding workmen sufficiently skilled in mechanics, and
in the use of tools, to follow his instructions and embody his designs in
a practical shape. The tools then in use about the collieries were rude
and clumsy; and there were no such facilities as now exist for turning
out machinery of an entirely new character. Stephenson was under the
necessity of working with such men and tools as were at his command; and
he had in a great measure to train and instruct the workmen himself. The
engine was built in the workshops at the West Moor, the leading mechanic
employed being the colliery blacksmith, an excellent workman in his way,
though quite new to the work now entrusted to him.
In this first locomotive constructed at Killingworth, Stephenson to some
extent followed the plan of Blenkinsop's engine. The boiler was
cylindrical, of wrought iron, 8 feet in length and 34 inches in diameter,
with an internal flue-tube 20 inches wide passing through it. The engine
had two vertical cylinders of 8 inches diameter, and 2 feet stroke, let
into the boiler, working the propelling gear with cross heads and
connecting rods. The power of the two cylinders was combined by means of
spurwheels, which communicated the motive power to the wheels supporting
the engine on the rail, instead of, as in Blenkinsop's engine, to
cogwheels which acted on the cogged rail independent of the four
supporting wheels. The engine thus worked upon what is termed the second
motion. The chimney was of wrought iron, round which was a chamber
extending back to the feed-pumps, for the purpose of heating the water
previous to its injection into the boiler. The engine had no springs,
and was mounted on a wooden frame supported on four wheels. In order to
neutralise as much as possible the jolts and shocks which such an engine
would necessarily encounter from the obstacles and inequalities of the
then very imperfect plateway, the water-barrel which served for a tender
was fixed to the end of a lever and weighted, the other end of the lever
being connected with the frame of the locomotive carriage. By this means
the weight of the two was more equally distributed, though the
contrivance did not by any means compensate for the absence of springs.
[Picture: The Spur-gear]
The wheels of the locomotive were all smooth, Mr. Stephenson having
satisfied himself by experiment that the adhesion between the wheels of a
loaded engine and the rail would be sufficient for the purpose of
traction. Robert Stephenson informed us that his father caused a number
of workmen to mount upon the wheels of a waggon moderately loaded, and
throw their entire weight upon the spokes on one side, when he found that
the waggon could thus be easily propelled forward without the wheels
slipping. This, together with other experiments, satisfied him of the
expediency of adopting smooth wheels on his engine, and it was so
finished accordingly.
The engine was, after much labour and anxiety, and frequent alterations
of parts, at length brought to completion, having been about ten months
in hand. It was placed upon the Killingworth Railway on the 25th July,
1814; and its powers were tried on the same day. On an ascending
gradient of 1 in 450, the engine succeeded in drawing after it eight
loaded carriages of thirty tons' weight at about four miles an hour; and
for some time after it continued regularly at work.
Although a considerable advance upon previous locomotives, "Blutcher" (as
the engine was popularly called) was nevertheless a somewhat cumbrous and
clumsy machine. The parts were huddled together. The boiler constituted
the principal feature; and being the foundation of the other parts, it
was made to do duty not only as a generator of steam, but also as a basis
for the fixings of the machinery and for the bearings of the wheels and
axles. The want of springs was seriously felt; and the progress of the
engine was a succession of jolts, causing considerable derangement to the
machinery. The mode of communicating the motive power to the wheels by
means of the spur-gear also caused frequent jerks, each cylinder
alternately propelling or becoming propelled by the other, as the
pressure of the one upon the wheels became greater or less than the
pressure of the other; and when the teeth of the cogwheels became at all
worn, a rattling noise was produced during the travelling of the engine.
As the principal test of the success of the locomotive was its economy as
compared with horse power, careful calculations were made with the view
of ascertaining this important point. The result was, that it was found
the working of the engine was at first barely economical; and at the end
of the year the steam power and the horse power were ascertained to be as
nearly as possible upon a par in point of cost. The fate of the
locomotive in a great measure depended on this very engine. Its speed
was not beyond that of a horse's walk, and the heating surface presented
to the fire being comparatively small, sufficient steam could not be
raised to enable it to accomplish more on an average than about four
miles an hour. The result was anything but decisive; and the locomotive
might have been condemned as useless, had not our engineer at this
juncture applied the steam-blast, and by its means carried his experiment
to a triumphant issue.
The steam, after performing its duty in the cylinders, was at first
allowed to escape into the open atmosphere with a hissing blast, to the
terror of horses and cattle. It was complained of as a nuisance; and an
action at law against the colliery lessees was threatened unless it was
stopped. Stephenson's attention had been drawn to the much greater
velocity with which the steam issued from the exit pipe compared with
that at which the smoke escaped from the chimney. He conceived that, by
conveying the eduction steam into the chimney, by means of a small pipe,
after it had performed its office in the cylinders, allowing it to escape
in a vertical direction, its velocity would be imparted to the smoke from
the fire, or to the ascending current of air in the chimney, thereby
increasing the draft, and consequently the intensity of combustion in the
furnace.
The experiment was no sooner made than the power of the engine was at
once more than doubled; combustion was stimulated by the blast;
consequently the capability of the boiler to generate steam was greatly
increased, and the effective power of the engine augmented in precisely
the same proportion, without in any way adding to its weight. This
simple but beautiful expedient was really fraught with the most important
consequences to railway communication; and it is not too much to say that
the success of the locomotive has in a great measure been the result of
its adoption. Without the steam-blast, by means of which the intensity
of combustion is maintained at its highest point, producing a
correspondingly rapid evolution of steam, high rates of speed could not
have been kept up; the advantages of the multi-tubular boiler (afterwards
invented) could never have been fairly tested; and locomotives might
still have been dragging themselves unwieldily along at little more than
five or six miles an hour.
The steam-blast had scarcely been adopted, with so decided a success,
when Stephenson, observing the numerous defects in his engine, and
profiting by the experience which he had already acquired, determined to
construct a second engine, in which to embody his improvements in their
best form. Careful and cautious observation of the working of his
locomotive had convinced him that the complication arising out of the
action of the two cylinders being combined by spur-wheels would prevent
its coming into practical use. He accordingly directed his attention to
an entire change in the construction and mechanical arrangements of the
machine; and in the following year, conjointly with Mr. Dodds, who
provided the necessary funds, he took out a patent, dated the 28th of
February, 1815, for an engine which combined in a remarkable degree the
essential requisites of an economical locomotive; that is to say, few
parts, simplicity in their action, and directness in the mode by which
the power was communicated to the wheels supporting the engine.
This locomotive, like the first, had two vertical cylinders, which
communicated _directly_ with each pair of the four wheels that supported
the engine, by means of a cross head and a pair of connecting rods. But
in attempting to establish a direct communication between the cylinders
and the wheels that rolled upon the rails, considerable difficulties
presented themselves. The ordinary joints could not be employed to unite
the parts of the engine, which was a rigid mass, with the wheels lolling
upon the irregular surface of the rails; for it was evident that the two
rails of the line of way--more especially in those early days of
imperfect construction of the permanent road--could not always be
maintained at the same level,--that the wheel at one end of the axle
might be depressed into one part of the line which had subsided, whilst
the other wheel would be comparatively elevated; and in such a position
of the axle and wheels, it was obvious that a rigid communication between
the cross head and the wheels was impracticable. Hence it became
necessary to form a joint at the top of the piston-rod where it united
with the cross head, so as to permit the cross head to preserve complete
parallelism with the axle of the wheels with which it was in
communication.
In order to obtain that degree of flexibility combined with direct
action, which was essential for ensuring power and avoiding needless
friction and jars from irregularities in the road, Stephenson made use of
the "ball and socket" joint for effecting a union between the ends of the
cross heads where they united with the connecting rods, and between the
ends of the connecting rods where they were united with the crank-pins
attached to each driving-wheel. By this arrangement the parallelism
between the cross head and the axle was at all times maintained and
preserved, without producing any serious jar or friction on any part of
the machine. Another important point was, to combine each pair of wheels
by means of some simple mechanism instead of by the cogwheels which had
formerly been used. And, with this object, Stephenson made cranks in
each axle at right angles to each other, with rods communicating
horizontally between them.
A locomotive was constructed upon this plan in 1815, and was found to
answer extremely well. But at that period the mechanical skill of the
country was not equal to forging cranked axles of the soundness and
strength necessary to stand the jars incident to locomotive work.
Stephenson was accordingly compelled to fall back upon a substitute,
which, although less simple and efficient, was within the mechanical
capabilities of the workmen of that day, in respect of construction as
well as repair. He adopted a chain which rolled over indented wheels
placed on the centre of each axle, and was so arranged that the two pairs
of wheels were effectually coupled and made to keep pace with each other.
The chain, however, after a few years' use, became stretched; and then
the engines were liable to irregularity in their working, especially in
changing from working back to working forward again. Eventually the
chain was laid aside, and the front and hind wheels were united by rods
on the outside, instead of by rods and crank axles inside, as specified
in the original patent. This expedient completely answered the purpose
required, without involving any expensive or difficult workmanship.
Thus, in 1815, by dint of patient and persevering labour,--by careful
observation of the works of others, and never neglecting to avail himself
of their suggestions,--Stephenson succeeded in manufacturing an engine
which included the following important improvements on all previous
attempts in the same direction:--viz., simple and direct communication
between the cylinders and the wheels rolling upon the rails; joint
adhesion of all the wheels, attained by the use of horizontal
connecting-rods; and finally, a beautiful method of exciting the
combustion of the fuel by employing the waste steam, which had formerly
been allowed to escape uselessly into the air. Although many
improvements in detail were afterwards introduced in the locomotive by
George Stephenson himself, as well as by his equally distinguished son,
it is perhaps not too much to say that this engine, as a mechanical
contrivance, contained the germ of all that has since been effected. It
may in fact be regarded as the type of the present locomotive engine.