THE LOCOMOTIVE ENGINE--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 wagons still continued to be drawn by horses.
By improving and flattening the tram-way, considerable economy in
horse-power had 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.
Notwithstanding Trevithick's comparatively successful experiment with
the first railway locomotive on the Merthyr Tydvil tram-road in 1804,
described in a former chapter, he seems to have taken no farther steps
to bring his invention into notice. He was probably discouraged by the
breakage of the cast-iron plates, of which the road was formed, which
were crushed under the load of his engine, and could not induce the
owners of the line to relay it with better materials so as to give his
locomotive a fair trial.
An imaginary difficulty, also, seems to have tended, among other
obstacles, to prevent the adoption of the locomotive, 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 any progress.[31]
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
thereby be better secured.
Trevithick himself does not seem to have erected another engine, but we
gather from the evidence given by Mr. Rastrick in the committee on the
Liverpool and Manchester Bill in 1825, that ten or twelve years before
that time he had made an engine for Trevithick after his patent, and
that the engine was exhibited in London. "A circular railroad was laid
down," said Mr. Rastrick, "and it was stated that this engine was to
run against a horse, and that which went a sufficient number of miles
was to win." It is not known what afterward became of this engine.
There were, however, at a much earlier period, several wealthy and
enterprising men, both in Yorkshire and Northumberland, who were
willing to give the locomotive a fair trial; and had Trevithick but
possessed the requisite tenacity of purpose--had he not been too soon
discouraged by partially successful experiments--he might have risen to
both fame and fortune, not only as the inventor of the locomotive, but
as the practical introducer of railway locomotion.
One of Trevithick's early friends and admirers was Mr. Blackett,
of Wylam. The Wylam wagon-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
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-wagon had a
man in charge of it, and was originally drawn by one horse. The rate
at which the wagons 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 wagon-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 tram-road
worked by horses.
Mr. Blackett was the first colliery owner in the North who took
an active interest in the locomotive. He had witnessed the first
performances of Trevithick's steam-carriage in London, and was so taken
with the idea of its application to railway locomotion that he resolved
to have an engine erected after the new patent for use upon his
tram-way at Wylam. 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 foundery there. The engine was made under the superintendence
of one John Steele,[32] 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 backward and forward many times. For
some reason or other, however--it is said because the engine was 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 foundery,
in which service it long continued to be employed.
Several years elapsed before Mr. Blackett took any farther steps to
carry out his idea. The final abandonment of Trevithick's locomotive at
Pen-y-darran perhaps contributed to deter him from proceeding farther;
but he had the Wylam wooden tram-way taken up in 1808, and a plate-way
of cast iron laid down instead--a single line furnished with sidings
to enable the laden wagons 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 enabled to draw two, or even three laden
wagons.
[Illustration: BLENKINSOP'S LEEDS ENGINE.]
Although the locomotive seemed about to be lost sight of, it was not
forgotten. In 1811, Mr. Blenkinsop, the manager of the Middleton
Collieries, near Leeds, revived the idea of employing it in lieu of
horses to haul the coals along his tram-way. Mr. Blenkinsop, in the
patent which he took out for his proposed engine, followed in many
respects the design of Trevithick; but, with the help of Matthew
Murray, of Leeds, one of the most ingenious mechanics of his day,
he introduced several important and valuable modifications. Thus
he employed two cylinders of 8 in. diameter instead of one, as in
Trevithick's engine. These cylinders were placed vertically, and
immersed for more than half their length in the steam space of the
boiler. The eduction pipes met in a single tube at the top, and threw
the steam into the air. The boiler was cylindrical in form, but of
cast iron. It had one flue, the fire being at one end and the chimney
at the other. The engine was supported on a carriage without springs,
resting directly upon two pairs of wheels and axles unconnected with
the working parts, and which merely served to carry the engine upon the
rails. The motion was effected in this way: the piston-rods, by means
of cross-heads, worked the connecting-rods, which came down to two
cranks on each side below the boiler, placed at right angles in order
to pass their centres with certainty. These cranks worked two shafts
fixed across the engine, on which were small-toothed wheels working
into a larger one between them; and on the axis of this large wheel,
outside the framing, were the driving-wheels, one of which was toothed,
and worked into a rack on one side of the railway.
It will be observed that the principal new features in this engine were
the two cylinders and the toothed-wheel working into a rack-rail. Mr.
Blenkinsop contrived the latter expedient in order to insure sufficient
adhesion between the wheel and the road, supposing that smooth wheels
and smooth rails would be insufficient for the purpose. Clumsy and
slow though the engine was compared with modern locomotives, it was
nevertheless a success. It was the first engine that plied regularly
upon any railway, doing useful work; and it continued so employed for
more than twenty years. What was more, it was a commercial success, for
its employment was found to be economical compared with horse-power.
In a letter to Sir John Sinclair, Mr. Blenkinsop stated that his
engine weighed five tons; consumed two thirds of a hundred weight of
coals and fifty gallons of water per hour; drew twenty-seven wagons,
weighing ninety-four tons, on a dead level, at three and a half miles
an hour, or fifteen tons up an ascent of 2 in. in the yard; that when
"lightly loaded" it traveled at a speed of ten miles an hour; that it
did the work of sixteen horses in twelve hours; and that its cost was
£400. Such was Mr. Blenkinsop's own account of the performances of
his engine, which was for a long time regarded as one of the wonders
of the neighborhood.[33] The Messrs. Chapman, of Newcastle, in 1812
endeavored 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 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 very soon abandoned. Another remarkable
expedient was adopted by Mr. Brunton, of the Butterley Works,
Derbyshire, who in 1813 patented his Mechanical Traveler, to go _upon
legs_ working alternately like those of a horse.[34] 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 by-standers, wounding
many more. These, and other contrivances with the same object,
projected about the same time, show that invention was busily at work,
and that many minds were anxiously laboring to solve the problem of
steam locomotion on railways.
Mr. Blackett, of Wylam, was encouraged by the success of Mr.
Blenkinsop's experiment, and again he resolved to make a trial of
the locomotive upon his wagon-way. Accordingly, in 1812, he ordered
a second engine, which was so designed as to work with a toothed
driving-wheel upon a rack-rail as at Leeds. 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. Like Trevithick's, it had a
single cylinder with a fly-wheel, which Blenkinsop had discarded. The
boiler was of cast iron. 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 wagon, 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 labor, 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 making yet another trial. He accordingly directed
his engine-wright, Jonathan Foster, 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. The engine proved more successful
than the former one, and it was found capable of dragging eight or nine
loaded wagons, 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 out
to drag the wagons as before, and others to haul the engine back to the
workshops. It was constantly getting out of order; its plugs, pumps,
or cranks got wrong, and it was under repair as often as at work. At
length it became so cranky that the horses were usually sent after it
to drag it along when it gave up, and the workmen generally declared
it to be a "perfect plague." Mr. Blackett did not obtain credit among
his neighbors for these experiments. Many laughed at his machines,
regarding them only in the light of crotchets--frequently quoting the
proverb of "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 the 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
sufficient adhesion 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 then 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 wagons 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 wagons upon a moderately level road.[35]
From this time forward, considerably less difficulty was experienced
in working the coal-trains upon the Wylam tram-road. 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.[36] Below
is a representation of this improved Wylam engine.
[Illustration: 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 neighboring 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 vehicle drawn by 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
sight. Much interruption was thus caused to the working of the railway,
and it excited considerable dissatisfaction among the workmen. The
following plan was adopted to abate the nuisance: a reservoir was
provided immediately behind the chimney (as shown in the opposite
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. This arrangement was devised
with the express object of preventing a blast in the chimney, the
value of which, as we shall subsequently find, was not detected until
George Stephenson, adopting it with a preconceived design and purpose,
demonstrated its importance and value--as being, in fact, the very
life-breath of the locomotive engine.
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,
for the purpose of 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 labor.
The coals, when brought above ground, had next to be laboriously
dragged by means of horses to the shipping staiths on the Tyne, several
miles distant. The adoption of a tram-road, it is true, had tended to
facilitate their transit; nevertheless, the haulage was both tedious
and expensive. With the view of economizing labor, Stephenson laid
down inclined planes where the nature of the ground would admit of
this expedient being adopted. Thus a train of full wagons let down
the incline by means of a rope running over wheels laid along the
tram-road, the other end of which was attached to a train of empty
wagons 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 means of horses--the keep of
which was at that time very costly, in consequence of the high price of
corn--was still a great desideratum, and the best practical minds in
the collieries were actively engaged in trying 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[37] to inspect the improvements made by Mr.
Blackett from time to time both in the locomotive and in the plate-way
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 tram-way leading
from the collieries of Kenton and Coxlodge, on the 2d of September,
1813. This locomotive drew sixteen chaldron wagons, 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 among
the crowd of spectators that day; and after examining the engine and
observing its performances, he remarked 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, were in a
great measure practical failures. Mr. Blackett's was as yet both clumsy
and expensive. Chapman's had been removed from the Heaton tram-way 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 shortly blown up,
there was an end of that engine, and the colliery owners did not feel
encouraged to try any farther experiment.
An efficient and economical working locomotive engine, therefore, still
remained to be invented, and to accomplish this object Stephenson now
applied himself. Profiting by what his predecessors had done, warned by
their failures and encouraged by their partial successes, he commenced
his labors. 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, 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 labors to society and civilization.
He proceeded to bring the subject of constructing a "Traveling 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 favorable opinion of
the new colliery 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 authorized 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,[38] 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 intrust 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 being John Thirlwall, the colliery
blacksmith, an excellent mechanic in his way, though quite new to the
work now intrusted to him.
[Illustration: THE SPUR-GEAR.]
In this first locomotive constructed at Killingworth, Stephenson to
some extent followed the plan of Blenkinsop's engine. The wrought-iron
boiler was cylindrical, eight feet in length and thirty-four inches in
diameter, with an internal flue-tube twenty inches wide passing through
it. The engine had two vertical cylinders of eight inches diameter and
two feet stroke let into the boiler, which worked the propelling gear
with cross-heads and connecting-rods. The power of the two cylinders
was combined by means of spur-wheels, which communicated the motive
power to the wheels supporting the engine on the rail, instead of, as
in Blenkinsop's engine, to cog-wheels 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 neutralize 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 plate-way, 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 total absence of springs.
The wheels of the locomotive were all smooth, 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 wagon moderately loaded, and
throw their entire weight upon the spokes on one side, when he found
that the wagon could thus be easily propelled forward without the
wheels slipping. This, together with other experiments, satisfied him,
as it had already satisfied Mr. Hedley, of the expediency of adopting
smooth wheels on his engine, and it was so made accordingly.
The engine was, after much labor 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 of
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, "Blucher"
(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 cog-wheels became at all worn, a rattling noise was
produced during the traveling 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.
We give the remainder of the history of George Stephenson's efforts
to produce an economical working locomotive in the words of his son
Robert, as communicated to the author in 1856, for the purposes of his
father's "Life."
"A few months of experience and careful observation upon the
operation of this (his first) engine convinced my father that the
complication arising out of the action of the two cylinders being
combined by spur-wheels would prevent their coming into practical
application. He then directed his attention to an entire change in
the construction and mechanical arrangements, and in the following
year took out a patent, dated February 28th, 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 great simplicity in the mode by which power was
communicated to the wheels supporting the engine.
"This second engine consisted as before of two vertical
cylinders, which communicated directly with each pair of the
four wheels that supported the engine by 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 engine,
which was a rigid mass, with the wheels rolling upon the irregular
surface of the rails; for it was evident that the two rails of the
line of railway could not always be maintained at the same level
with respect to each other--that one wheel at the end of the axle
might be depressed into a part of the line which had subsided,
while the other would be elevated. In such a position of the
axle and wheels it was clear 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 always
to preserve complete parallelism with the axle of the wheels with
which it was in communication.
"In order to obtain the flexibility combined with direct action
which was essential for insuring power and avoiding needless
friction and jars from irregularities in the rail, my father
employed 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 end 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, it being
permitted to take place without producing jar or friction upon any
part of the machine.
"The next important point was to combine each pair of wheels by
some simple mechanism, instead of the cog-wheels which had formerly
been used. My father began by inserting each axle into two cranks
at right angles to each other, with rods communicating horizontally
between them. An engine was made on this plan, and answered
extremely well. But at that period (1815) the mechanical skill of
the country was not equal to the task of forging cranked axles of
the soundness and strength necessary to stand the jars incident
to locomotive work; so my father was compelled to fall back upon
a substitute which, though less simple and less efficient, was
within the mechanical capabilities of the workmen of that day,
either for construction or repair. He adopted a chain which rolled
over indented wheels placed on the centre of each axle, and so
arranged that the two pairs of wheels were effectually coupled and
made to keep pace with each other. But these chains 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 forward again. Nevertheless, these engines continued in
profitable use upon the Killingworth Colliery Railway for some
years. 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-ankles _inside_, as specified in the original patent; and
this expedient completely answered the purpose required, without
involving any expensive or difficult workmanship.
[Illustration: SECTION OF KILLINGWORTH LOCOMOTIVE, 1815.]
"Another important improvement was introduced in this engine. The
eduction steam had hitherto been allowed to escape direct into the
open atmosphere; but my father, having observed the great velocity
with which the waste-steam escaped, compared with the velocity
with which the smoke issued from the chimney of the same engine,
thought that by conveying the eduction steam into the chimney, and
there allowing it to escape in a vertical direction, its velocity
would be imparted to the smoke from the engine, or to the ascending
current of air in the chimney. The experiment was no sooner made
than the power of the engine became more than doubled; combustion
was stimulated, as it were, by a blast; consequently, the power of
the boiler for generating steam was increased, and, in the same
proportion, the useful duty of the engine was augmented.
"Thus, in 1815, my father had succeeded in manufacturing an engine
which included the following important improvements on all previous
attempts in the same direction: simple and direct communication
between the cylinder 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 fuel by employing the waste steam which had formerly
been allowed uselessly to escape. 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 be regarded, in
fact, as a type of the present locomotive engine.
"In describing my father's application of the waste steam for the
purpose of increasing the intensity of combustion in the boiler,
and thus increasing the power of the engine without adding to its
weight, and while claiming for this engine the merit of being
a type of all those which have been successfully devised since
the commencement of the Liverpool and Manchester Railway, it is
necessary to observe that the next great improvement in the same
direction, the 'multitubular boiler,' which took place some years
later, could never have been used without the help of that simple
expedient, _the steam-blast_, by which power only the burning of
coke was rendered possible.
"I can not pass over this last-named invention of my father's
without remarking how slightly, as an original idea, it has been
appreciated; and yet how small would be the comparative value of
the locomotive engine of the present day without the application of
that important invention!
"Engines constructed by my father in the year 1818 upon the
principles just described are in use on the Killingworth Colliery
Railway to this very day (1856), conveying, at the speed of
perhaps five or six miles an hour, heavy coal-trains, probably as
economically as any of the more perfect engines now in use.
"There was another remarkable piece of ingenuity in this machine,
which was completed so many years before the possibility of
steam-locomotion became an object of general commercial interest
and Parliamentary inquiry. I have before observed that up to and
after the year 1818 there was no such class of skilled mechanics,
nor were there such machinery and tools for working in metals, as
are now at the disposal of inventors and manufacturers. Among other
difficulties of a similar character, it was not possible at that
time to construct springs of sufficient strength to support the
improved engines. The rails then used being extremely light, the
roads became worn down by the traffic, and occasionally the whole
weight of the engine, instead of being uniformly distributed over
four wheels, was thrown almost diagonally upon two. In order to
avoid the danger arising from such irregularities in the road, my
father arranged the boiler so that it was supported upon the frame
of the engine by four cylinders which opened into the interior of
the boiler. These cylinders were occupied by pistons with rods,
which passed downward and pressed upon the upper side of the axles.
The cylinders, opening into the interior of the boiler, allowed the
pressure of steam to be applied to the upper side of the piston,
and that pressure being nearly equal to the support of one fourth
of the weight of the engine, each axle, whatever might be its
position, had the same amount of weight to bear, and consequently
the entire weight was at all times nearly equally distributed among
the wheels. This expedient was more necessary in this case, as
the weight of the new locomotive engines far exceeded that of the
carriages which had hitherto been used upon colliery railways, and
therefore subjected the rails to much greater risk from breakage.
And this mode of supporting the engine remained in use until the
progress of spring-making had considerably advanced, when steel
springs of sufficient strength superseded this highly ingenious
mode of distributing the weight of the engine uniformly among the
wheels."
The invention of the Steam-blast by George Stephenson in 1815 was
fraught with the most important consequences to railway locomotion, and
it is not saying too much to aver that the success of the locomotive
has been in a great measure 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 multitubular boiler (afterward invented) could
never have been fully tested; and locomotives might still have been
dragging themselves unwieldily along at little more than five or six
miles an hour.
As this invention has been the subject of considerable controversy, it
becomes necessary to add a few words respecting it in this place. It
has been claimed as the invention of Trevithick in 1804, of Hedley
in 1814, of Goldsworthy Gurney in 1820, and of Timothy Hackworth in
1829. With respect to Trevithick, it appears that he discharged the
waste steam into the chimney of his engine, but without any intention
of thereby producing a blast;[39] and that he attached no value to
the expedient is sufficiently obvious from the fact that in 1815 he
took out a patent for urging the fire by means of fanners, similar
to a winnowing machine. The claim put forward on behalf of William
Hedley, that he invented the blast-pipe for the Wylam engine, is
sufficiently contradicted by the fact that the Wylam engine had _no_
blast-pipe. "I remember the Wylam engine," Robert Stephenson wrote to
the author in 1857, "and I am positive there was no blast-pipe." On
the contrary, the Wylam engine embodied a contrivance for the express
purpose of _preventing_ a blast. This is clearly shown by the drawing
and description of it contained in the first edition of Nicholas Wood's
"Practical Treatise on Railroads," published in 1825. This evidence is
all the more valuable for our purpose as it was published long before
any controversy had arisen as to the authorship of the invention, and,
indeed, before it was believed that any merit whatever belonged to it.
And it is the more remarkable, as Nicholas Wood himself, who published
the first practical work on railways, did not at that time approve of
the steam-blast, and referred to the Wylam engine in illustration of
how it might be prevented.
The following passage from Mr. Wood's book clearly describes the
express object and purpose for which George Stephenson invented and
applied the steam-blast in the Killingworth engines. Describing their
action, Mr. Wood says:
"The steam is admitted to the top and bottom of the piston by means
of a sliding valve, which, being moved up and down alternately,
opens a communication between the top and bottom of the cylinder
and the pipe that is _open into the chimney and turns up within
it_. The steam, after performing its office within the cylinder, is
thus thrown into the chimney, and the power with which it issues
will be proportionate to the degree of elasticity; and _the exit
being directed upward, accelerates the velocity of the current of
heated air accordingly_."[40]
And again, at another part of the book, he says:
"There is another great objection urged against locomotives,
which is, the noise that the steam makes in escaping into the
chimney; this objection is very singular, as it is not the result
of any inherent form in the organization of such engines, but an
accidental circumstance. When the engines _were first made_, the
steam escaped into the atmosphere, and made comparatively little
noise; _it was found difficult then to produce steam in sufficient
quantity to keep the engine constantly working, or rather to obtain
an adequate rapidity of current in the chimney to give sufficient
intensity to the fire. To effect a greater rapidity, or to increase
the draught of the chimney, Mr. Stephenson thought that by causing
the steam to escape into the chimney through a pipe with its end
turned upward, the velocity of the current would be accelerated,
and such was the effect_; but, in remedying one evil, another has
been produced, which, though objectionable in some places, was not
considered as objectionable on a private railroad. The tube through
the boiler having been increased, there is now no longer any
occasion for the action of the steam to assist the motion of the
heated air in the chimney. The steam thrown in this manner into the
chimney acts as a trumpet, and certainly makes a very disagreeable
noise. Nothing, however, is more easy to remedy, and the very act
of remedying this defect will also be the means of economizing the
fuel."[41]
Mr. Wood then proceeds to show how the noise caused by the blast--how,
in fact, the blast itself, might be effectually prevented by adopting
the expedient employed in the Wylam engine; which was, to send the
exhaust steam, not into the chimney (where alone the blast could act
with effect by stimulating the draught), but into a steam-reservoir
provided for the purpose. His words are these:
"Nothing more is wanted to destroy the noise than _to cause the
steam to expand itself into a reservoir, and then allow it to
escape gradually to the atmosphere through the chimney._ Upon the
Wylam railroad the noise was made the subject of complaint by a
neighboring gentleman, and they adopted this mode, which had the
effect above mentioned."[42]
It is curious to find that Mr. Nicholas Wood continued to object to
the use of the steam-blast down even to the time when the Liverpool
and Manchester Railway Bill was before Parliament. In his evidence
before the Committee on that Bill in 1825, he said: "Those engines [at
Killingworth] _puff very much, and the object is to get an increased
draught in the chimney_. Now (by enlarging the flue-tube and giving it
a double turn through the boiler) we have got a sufficiency of steam
without it, and I have no doubt, by allowing the steam to exhaust
itself in a reservoir, it would pass quietly into the chimney without
that noise." In fact, Mr. Wood was still in favor of the arrangement
adopted in the Wylam engine, by which the steam-blast had been got rid
of altogether.
If these statements, made in Mr. Wood's book, be correct--and they
have never been disputed--they render it perfectly clear that George
Stephenson invented and applied the steam-blast for the express
purpose of quickening combustion in the furnace by increasing the
draught in the chimney. Although urged by Wood to abandon the blast,
Stephenson continued to hold by it as one of the vital powers of the
locomotive engine. It is quite true that in the early engines, with
only a double flue passing through the boiler, run as they were at
low speeds, the blast was of comparatively less importance. It was
only when the improved passenger engine, fitted with the multitubular
boiler, was required to be run at high speeds that the full merits of
the blast were brought out; and in detecting its essential uses in this
respect, and sharpening it for the purpose of increasing its action,
the sagacity of Timothy Hackworth, of Darlington, is entitled to due
recognition.
[Illustration: (Colliery Whimsey)]
FOOTNOTES:
[31] The same fallacy seems long to have held its ground in France;
for M. Granier tells us that some time after the first of George
Stephenson's locomotives had been placed on the Liverpool and
Manchester line, a model of one was exhibited before the Academy. After
it had been examined, a member of that learned body said, smiling,
"Yes, this is all very ingenious, no doubt, but unfortunately the
machine will never move. The wheels will turn round and round in the
same place."
[32] John Steele was one of the many "born mechanics" of the
Northumberland district. When a boy at Colliery Dykes, his native
place, he was noted for his "turn for machinery." He used to take his
playfellows home to see and admire his imitations of pit-engines. While
a mere youth he lost his leg by an accident; and those who remember
him at Whinfield's speak of his hopping about the locomotive, of which
he was very proud, upon his wooden leg. It was a great disappointment
to him when Mr. Blackett refused to take the engine. One day he took
a friend to look at it when reduced to its degraded office of blowing
the cupola bellows; and, referring to the cause of its rejection, he
observed that he was certain it would succeed, if made sufficiently
heavy. "Our master," he continued, "will not be at the expense of
following it up; but depend upon it the day will come when such an
engine will be fairly tried, and then it will be found to answer."
Steele was afterward extensively employed by the British government in
raising sunken ships; and later in life he established engine-works at
Rouen, where he made marine-engines for the French government. He was
unfortunately killed by the explosion of an engine-boiler (with the
safety-valve of which something had gone wrong) when on an experimental
trip with one of the steamers fitted up by himself, and on his way to
England to visit his family near Newcastle.
[33] Thomas Gray, a native of Leeds, was an enthusiastic believer in
the new tractive power, and wherever he went he preached up railways
and Blenkinsop's locomotive. While he was living at Brussels in 1816,
a canal to Charleroi was under consideration, on which he seized
the opportunity of urging the superior merits of a railway. When
he returned to England in 1820, he wrote a book upon the subject,
entitled, "Observations on a General Iron Railway," in which he
strongly advocated the advantages of railways generally, giving as
a frontispiece to the book an engraving of Blenkinsop's engine. And
several years after the opening of the Liverpool and Manchester Railway
we find Thomas Gray, true to his first love, urging in the "Mechanics'
Magazine" the superiority of Blenkinsop's cogged wheel and rail over
the smooth road and rail of the modern railway.
[34] Other machines with legs were patented in the following year
by Lewis Gompertz and by Thomas Tindall. In Tindall's specification
it is provided that the power of the engine is to be assisted by a
_horizontal windmill_; and the four pushers, or legs, are to be caused
to come successively in contact with the ground, and impel the carriage.
[35] Mr. Hedley took out a patent to secure his invention, dated the
13th of March, 1813. Specification No. 3666. If it be true, as alleged,
that the wheels of Trevithick's first locomotive were smooth, it seems
strange that the fallacy should ever have existed.
[36] By the year 1825, the progress made on the Wylam Railroad was
thus described by Mr. Mackenzie in his "History of Northumberland:" "A
stranger," said he, "is struck with surprise and astonishment on seeing
a locomotive engine moving majestically along the road at the rate of
four or five miles an hour, drawing along from ten to fourteen loaded
wagons, weighing about 21-1/2 tons; and his surprise is increased on
witnessing the extraordinary facility with which the engine is managed.
This invention is a noble triumph of science."
[37] At the Stephenson Memorial meeting at Newcastle-on-Tyne, 26th of
October, 1858, Mr. Hugh Taylor, chairman of the Northern Coal-owners,
gave the following account of one of such visits made by Stephenson
to Wylam, in the company of Mr. Nicholas Wood and himself: "It was, I
think, in 1812, that Mr. Stephenson and Mr. Wood came to my house, then
at Newburn, and after we had dined, we went and examined the locomotive
then on Mr. Blackett's wagon-way. At that early date it went by a sort
of cog-wheel; there was also something of a chain to it. There was no
idea that the machine would be sufficiently adhesive to the rails by
the action of its own weight; but I remember a man going before--that
was after the chain was abrogated--and scattering ashes on the rails,
in order to give it adhesiveness, and two or three miles an hour was
about the rate of progress."
[38] Speech at the opening of the Newcastle and Darlington Railway,
June 18, 1844.
[39] It must, however, be mentioned that Mr. Zerah Colburn, in his
excellent work on "Locomotive Engineering and the Mechanism of
Railways," points out that Mr. Davies Gilbert noted the effect of the
discharge of the waste steam up the chimney of Trevithick's engine in
increasing the draught, and wrote a letter to "Nicholson's Journal"
(Sept., 1805) on the subject; and Mr. Nicholson himself proceeded
to investigate the subject, and in 1806 he took out a patent for
"steam-blasting apparatus," applicable to fixed engines, which,
however, does not seem to have come into use. (See _ante_, p. 82.)
[40] Nicholas Wood, "Practical Treatise on Railways," ed. 1825, p. 147.
[41] Ibid., p. 292-3.
[42] Nicholas Wood, "Practical Treatise on Railways," ed. 1825, p.
294. These passages will be found in the first edition of Mr. Wood's
work, published in 1825. The subsequent editions do not contain them.
A few years' experience wrought great changes of opinion on many
points connected with the practical working of railways, and Mr. Wood
altered his text accordingly. But it is most important for our present
purpose to note that, in the year 1825, long before the Liverpool and
Manchester line was opened, Mr. Wood should have so clearly described
the steam-blast, which had been in regular use for more than ten
years in all Stephenson's locomotives employed in the working of the
Killingworth railway.