GLANCING BACKWARDS AND STRUGGLING FORWARDS.
“My lord, will you spend the money to build a Travelling Engine?”
“Why? what would it do?”
“Haul coals to the Tyne, my lord. The present system of hauling by
horses is very costly.”
“It is. But how would you manage it by a Travelling Engine?” Thereupon
George Stephenson the engine-wright proceeded to explain.
In some such manner as this we can imagine that Stephenson opened up
the subject to Lord Ravensworth, the chief partner in the Killingworth
Colliery; and he won his lordship over.
Stephenson had already improved the colliery engines, and Lord
Ravensworth had formed a high opinion of his abilities. So after
consideration he gave the required consent.
Now, let us endeavour to imagine the position. The steam engine, of
which the locomotive is one form, had been invented years before. The
Marquis of Worcester made something of a steam engine which apparently
was working at Vauxhall, South-west London, in 1656. It is said that he
raised water forty feet, and by this we may infer that his apparatus
was a steam-pump. He describes it in his work “Century of Inventions,”
about 1655, and he is generally accredited with being the inventor of
the steam engine. It was, however, a very primitive affair, the boiler
being the same vessel as that in which the steam accomplished its work.
Captain Savery took the next step. He was the first to obtain a patent
for applying steam power to machinery. This was in 1698, and he used
a boiler distinct from the vessel where the steam was to exert its
power. Savery’s engines appear to have been used to drain mines.
His engines acted in this way—the steam was condensed in a vessel and
produced a vacuum which raised the water; then the steam pressing upon
it raised it further in another receptacle.
An obvious improvement was the introduction of the piston. This was
Papin’s idea, and he used it first in 1690. Six years later an engine
was constructed by Savery, Newcomen (a Devonshire man), and Cawley,
in which the “beam” was introduced, and also the ideas of a distinct
boiler separate from a cylinder in which worked a piston. This machine
was in operation for about seventy years. The beam worked on an axle
in its centre—something like a child’s “see-saw,” and one end being
attached to the piston moving in the cylinder, it was worked up and
down, the other end of the beam being fastened to the pump-rod, which
was thus alternately raised and depressed.
The upward movement of the piston having been effected by a rush of
steam from the boiler upon its head, the steam was cut off and cold
water run in upon it from a cistern. The steam was thus condensed by
the water and a vacuum caused, and the piston was pressed down by the
weight of the atmosphere—of course dragging down its end of the beam,
and raising the pump-rod. The steam was then turned on again and pushed
up the piston, and consequently the end of the beam also. Thus the
engine continued to work, the turning of the cocks to admit steam and
water being performed by an attendant. The engine was, however, made
self-acting in this respect, and Smeaton improved this form of engine
greatly. The beam is still used in engines for pumping.
Nevertheless, improved though it became, it was still clumsy and almost
impracticable. It was the genius of James Watt which changed it from a
slow, awkward, cumbrous affair into a most powerful, practicable, and
useful machine.
His great improvements briefly were these: he condensed the steam in
a separate vessel from the cylinder, and thus avoided cooling it and
the consequent loss of steam power; secondly, he used the steam to
push back the piston as well as to push it forward (this is called the
“double-acting engine,” and is now always used); thirdly, he introduced
the principle of using the steam expansively, causing economy in
working; and fourthly, he enabled a change to be made of the up and
down motion of the piston into a circular motion by the introduction of
the crank.
[Illustration: JAMES WATT.]
The use of the steam expansively is to stop its rush to the cylinder
when the piston has only partially accomplished its stroke, leaving the
remainder of the stroke to be driven by the expansion of the steam.
In early engines the steam was admitted by conical valves, worked by a
rod from the beam. Murdock, we may add in parenthesis, is believed to
have invented the slide-valve which came into use as locomotives were
introduced, and of which there are now numerous forms. The valve is
usually worked by an “eccentric” rod on the shaft of the engine.
Watt was the author of many other inventions and improvements of the
steam engine. Indeed, although Savery and Newcomen and others are
entitled to great praise, it was Watt who gave it life, so to speak,
and made it, in principle and essence, very much that which we now
possess. There have, indeed, been improvements as to the boiler, as to
expansive working, and in various details, since his day; but, apart
from the distinctive forms of the locomotive and the marine engine, the
machine as a whole is in principle much as Watt left it.
The centre of all things in a steam engine is usually the cylinder.
Here the piston is moved backward and forward, and thence gives motion
as required to other parts of the machine.
The cylinder is in fact an air-tight, round box, fitted with a
close-fitting, round plate of metal, to which is fixed the piston-rod.
Now, it must be obvious that if the steam be admitted at one end of the
cylinder it will, as it rushes in, push the metal plate and the piston
outward, and if this steam be cut off, and the steam admitted to the
other end of the cylinder, it will push the metal plate and piston back
again.
But what is to be done with the steam after it has accomplished
its work? It may be permitted to spurt out into the air, or into a
separate vessel, where it may be condensed. In the locomotive, under
Stephenson’s able handling, this escape of steam was created into a
steam-blast in the chimney to stimulate the fire. In compound and
triple-expansion engines the steam is used—or expanded, it is called—in
two or three cylinders respectively. When steam is condensed, it may
be returned to the boiler as water.
It was the repairing of a Newcomen engine that seems to have started
Watt on his inventions and improvements of the steam engine. He was
then a mathematical instrument maker at Glasgow. As a boy he had
suffered from poor health, but had been very observant and studious;
and it is said that his aunt chided him on one occasion for wasting
time in playing with her tea-kettle. He would watch the steam jetting
from its spout, and would count the water-drops into which the steam
would condense when he held a cup over the white cloud.
Delicate though he was in health, he studied much, and came, indeed,
to make many other articles besides mathematical instruments. When,
therefore, the Newcomen engine needed repair, it was not unnatural
that it should be brought to him. It appears to have been a working
model used at Glasgow University. He soon repaired the machine; but,
in examining it, he became possessed with the idea that it was very
defective, and he pondered long over the problem—How it might be
improved. What was wanting in it? How could the steam be condensed
without cooling the cylinder?
Suddenly, one day, so the story goes, the idea struck him, when
loitering across the common with bent brows, that if steam were
elastic, it would spurt into any vessel empty of air. Impatiently,
he hastened home to try the experiment. He connected the cylinder of
an engine with a separate vessel, in which the air was exhausted,
and found that his idea was correct; the steam did rush into it.
Consequently the steam could be condensed in a separate vessel, and
the heat of the cylinder maintained and the loss of power prevented.
This invention seems simple enough; yet it increased the power of an
engine threefold, and is at the root of Watt’s fame. We must remember
that the inventions which in process of time may appear the simplest
and the most commonplace, may be the most difficult to originate. And
it may fairly be urged—If it were so very simple, and so very obvious,
why was it not invented before? The supposition is that in those days
it was not so simple. It is possible that the great elasticity of steam
was not sufficiently understood. In any case, the discovery and its
application are regarded as his greatest invention.
Yet ten years elapsed before he constructed a real working steam
engine, and so great we may suppose were the difficulties he
encountered, including poorness of health, that once he is reported
to have exclaimed: “Of all things in the world, there is nothing so
foolish as inventing.”
But a brilliant triumph succeeded. Eventually Watt became partner
with Mr. Matthew Boulton, and the firm of Boulton & Watt manufactured
the engine at Soho Ironworks, Birmingham. Mining proprietors soon
discovered the value of the new machine, and Newcomen’s engine was
superseded for pumping.
Watt continued to improve the machine, and together with Boulton also
greatly improved the workmanship of constructing engines and machinery.
In a patent taken out in 1784, he “described a steam locomotive”; but
for some reason he did not prosecute the idea. It is possible that the
notion of building a special road for it to run upon did not occur to
him, or appear very practicable.
His work was done, and it was a great work; but it was left for others
to develop the steam engine into forms for hauling carriages on land or
propelling ships upon the sea. Trevithick, Stephenson, and others did
the one; Symington, Bell, and others did the second. Watt died in 1819,
and though so delicate in youth, he lived to his eighty-fourth year.
The steam engine, therefore, as Watt left it, was practically as
Stephenson came to know it. He would be acquainted with it chiefly as
a pumping machine. But he saw what others had done to adopt it as a
locomotive, and he now set to work.
Stephenson’s first engine did not differ very materially from some of
those which had preceded it. He was, so to speak, feeling his way. The
machine had a round, wrought-iron boiler, eight feet long, with two
upright cylinders placed on the top of it. At the end of the pistons
from the cylinders were cross-rods connected with cogged wheels below
by other rods. These cogged wheels gave motion to the wheels running
on the rails by cogs not very far from the axles. Stephenson abandoned
the cogged rail, and adopted smooth wheels and smooth rails; but he did
not connect the driving-wheel direct with the piston, the intervening
cogged wheels being thought necessary to unite the power of the two
cylinders.
In adopting the principle of smooth wheels on smooth rails, it is said
that Stephenson proved by experiment that the arrangement would work
satisfactorily. Mr. Smiles writes that Robert Stephenson informed him,
“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.” Thus it may
be said that this obstacle—imaginary though it largely proved to be—was
cleared away from Stephenson’s first engine.
Ten months were occupied in building the machine, and at last came the
day of its trial. This was the 25th of July, 1814. Would it work?
Jolting and jerking along, it did work, hauling eight carriages at a
speed of about four or six miles an hour—as fast as a brisk man could
walk. Then came the question—Would it prove more economical than
horse-power?
Calculations therefore were made, and after a time it was found that
“Blucher” as the engine was called, though we believe its real name was
“My Lord,” was about as expensive as horse-power.
The locomotive needed something more, some magic touch to render it
less clumsy and more effective. What was it?
Then came the first great practicable improvement after the smooth
wheels on smooth rails. It was the steam-blast in the funnel, by which
the draught in the furnace was greatly increased. Indeed, the faster
the engine ran the more furiously the fire would burn, the more rapid
would be the production of steam, and the greater the power of the
engine.
At first Stephenson had allowed his waste steam from the cylinders
to blow off into the air. So great was the nuisance caused by this
arrangement that a law-suit was threatened if it were not abated.
What was to be done with that troublesome waste steam? Now, whether
Stephenson originated the idea or adapted what Trevithick had done,
we cannot say, but at all events he achieved the object, wherever he
gained the idea. He turned his exhaust steam through a pipe into the
funnel, and at a stroke increased the power of his engine two-fold.
But that expedient was not alone. Stephenson had watched the working of
“Blucher” to some purpose, and he decided to build another engine with
improvements.
The cumbersome cog-wheels must go; they complicated the machine
terribly, and prevented its practicability. Therefore in his second
engine he introduced direct connection between the pistons and the
wheels. There were a couple of upright cylinders as before, with
cross-rods attached to the piston-ends, and connecting rods from the
end of each cross-rod, reaching down to the wheels. But to overcome the
difficulty of one wheel being at some time higher than the other on
the poorly constructed railway of that period, a joint was introduced
in the cross-rod, so that if, perchance, the two wheels should not be
always on exactly the same level, no undue strain should be placed on
the cross-rod. Furthermore, the two pairs of wheels were combined first
by a chain, but afterwards by connecting rods. This may be called the
locomotive of 1815, the year in which the patent was taken out.
[Illustration: EDWARD PEASE.]
The engine accomplished its work more satisfactorily than before,
and was placed daily on the rails to haul coal from the mine to the
shipping point. But still its economy over horse-power was not so great
as to cause its wide adoption. And it was still little better, if
anything, than a mere coal haul.
Nevertheless Stephenson persevered. He was appointed engineer to the
Stockton and Darlington Railway—an enterprise largely promoted by Mr.
Edward Pease. It was opened on the 27th of September, 1825, and a local
paper writes as follows:—
“The signal being given, the engine started off with this immense
train of carriages, and such was its velocity, that in some parts the
speed was frequently 12 miles an hour; and at that time the number
of passengers was counted to be 450, which, together with the coals,
merchandise, and carriages, would amount to near 90 tons. The engine,
with its load, arrived at Darlington, a distance of 8¾ miles, in 65
minutes. The 6 waggons loaded with coals, intended for Darlington, were
then left behind; and obtaining a fresh supply of water, and arranging
the procession to accommodate a band of music and numerous passengers
from Darlington, the engine set off again, and arrived at Stockton in 3
hours and 7 minutes, including stoppages, the distance being nearly 12
miles.”
Stephenson became a partner in a business for constructing locomotives
at Newcastle, and three engines were made for the Stockton and
Darlington Railway. Nevertheless they appear to have been used chiefly
if not almost entirely for hauling coal; for the passenger-coach called
the _Experiment_ was hauled by a horse, and the journey occupied about
two hours.
The locomotive was not even yet a brilliant success over horse-power.
What was to be the next step?