Although the plan of this new edition of Beckmann’s ‘History of
Inventions and Discoveries’ was to confine it to the subjects treated
of in the original work, yet we feel it imperative to make an exception
in favour of the _Steam-Engine_, the most important of all modern
inventions.
The power of steam was not entirely unknown to the ancients, but
before the æra rendered memorable by the discoveries of JAMES WATT,
the steam-engine, which has since become the object of such universal
interest, was a machine of extremely limited power, inferior in
importance and usefulness to most other mechanical agents used as
prime movers. Hero of Alexandria, who lived about 120 years before the
birth of Christ, has left us the description of a machine, in which a
continued rotatory motion was imparted to an axis by a blast of steam
issuing from lateral orifices in arms placed at right angles to it.
About the beginning of the seventeenth century, a French engineer, De
Caus, invented a machine by which a column of water might be raised
by the pressure of steam confined in the vessel, above the water to
be elevated; and in 1629, Branca, an Italian philosopher, contrived a
plan of working several mills by a blast of steam against the vanes;
from the descriptions, however, which have been left us of these
contrivances, it does not appear that their projectors were acquainted
with those physical properties of elasticity and condensation on which
the power of steam as a mechanical agent depends.
In 1663, the celebrated Marquis of Worcester described in his Century
of Inventions, an apparatus for raising water by the expansive force
of steam only. From this work we extract the following short account
of the first steam-engine. “68. An admirable and most forcible way to
drive up water by fire; not by drawing or sucking it upwards, for that
must be as the philosopher calleth it, _intra sphæram activitatis_,
which is but at such a distance. But this way hath no bounder, if the
vessel be strong enough: for I have taken a piece of whole cannon,
whereof the end was burst, and filled it three-quarters full of water,
stopping and screwing up the broken end as also the touch-hole; and
making a constant fire under it, within twenty-four hours it burst and
made a great crack; so that having a way to make my vessels so that
they are strengthened by the force within them, and the one to fill
after the other, I have seen the water run like a constant stream,
forty feet high: one vessel of water rarefied by fire, driveth up forty
of cold water; and a man that tends the work is but to turn two cocks,
that one vessel of water being consumed, another begins to force and
refill with cold water, and so successively; the fire being tended
and kept constant, which the self-same person may likewise abundantly
perform in the interim, between the necessity of turning the said
cocks.”
The next name to be mentioned in connection with the progressive
history of the invention of the steam-engine, is that of Denis Papin, a
native of France, who, being banished from his country, was established
Professor of Mathematics at the University of Marburg, by the Landgrave
of Hesse. He first conceived the important idea of obtaining a
moving power by means of a piston working in a cylinder (1688), and
subsequently (1690) that of producing a vacuum in the cylinder by the
sudden condensation of steam by cold. In accordance with these ideas
he constructed a model consisting of a small cylinder, in which was
inserted a solid piston, and beneath this a small quantity of water;
on applying heat to the bottom of the cylinder, steam was generated,
the elastic force of which raised the piston; the cylinder was then
cooled by removing the fire, when the steam condensed and became again
converted into water, thus creating a vacuum in the cylinder, into
which the piston was forced by the pressure of the atmosphere; there
is, however, no evidence of his having carried that or any other
machine into practical use, before machines worked by steam had been
constructed elsewhere.
The first actual working steam-engine of which there is any record, was
invented by Captain Savery an Englishman, to whom a patent was granted
in 1698 for a steam-engine to be applied to the raising of water, &c.
This gentleman produced a working-model before the Royal Society, as
appears from the following extract from their Transactions:--“June
14th, 1699. Mr. Savery entertained the Royal Society with showing a
small model of his engine for raising water by help of fire, which
he set to work before them: the experiment succeeded according to
expectation, and to their satisfaction.” This engine, which was used
for some time to a considerable extent for raising water from mines,
consisted of a strong iron vessel shaped like an egg, with a tube or
pipe at the bottom, which descended to the place from which the water
was to be drawn, and another at the top, which ascended to the place
to which it was to be elevated. This oval vessel was filled with steam
supplied from a boiler, by which the atmospheric air was first blown
out of it. When the air was thus expelled, and nothing but pure steam
left in the vessel, the communication with the boiler was cut off, and
cold water poured on the external surface. The steam within was thus
condensed and a vacuum produced, and the water drawn up from below in
the usual way by suction. The oval steam-vessel was thus filled with
water; a cock placed at the bottom of the lower pipe was then closed,
and steam was introduced from the boiler into the oval vessel above the
surface of the water. This steam being of high pressure, forced the
water up the ascending tube, from the top of which it was discharged;
and the oval vessel being thus refilled with steam, the vacuum was
again produced by condensation, and the same process was repeated by
using two oval steam-vessels, which would act alternately; one drawing
water from below, while the other was forcing it upwards, by which an
uninterrupted discharge of water was produced. Owing to the danger of
explosion, from the high pressure of the steam which was used, and from
the enormous waste of heat by unnecessary condensation, these engines
soon fell into disuse.
Several ingenious men now turned their attention to the improvement of
the steam-engine, with a view to reduce the consumption of fuel, which
was found to be so immense as to preclude its use except under very
favourable circumstances; and in 1705, Thomas Newcomen, a blacksmith
or ironmonger, and John Cawley, a plumber and glazier, patented their
atmospheric engine, in which at first condensation was effected by
the affusion of cold water upon the external surface of the cylinder,
which was introduced into a hollow casing by which it was surrounded.
Having accidentally observed that an engine worked several strokes
with unusual rapidity without the supply of condensing water, Newcomen
found, on examining the piston, a hole in it through which the water
poured on to keep it air-tight issued in the form of a little jet,
and instantly condensed the steam under it; this led him to abandon
the casing and to introduce a pipe furnished with a cock, into the
bottom of the cylinder, by which water was supplied from a reservoir.
Newcomen’s engine required the constant attendance of some person to
open and shut the regulating and condensing valves, a duty which was
usually entrusted to boys, called _cock-boys_. It is said that one of
these boys, named Humphrey Potter, wishing to join his comrades at
play, without exposing himself to the consequences of suspending the
performance of the engine, contrived by attaching strings of proper
length to the levers which governed the two cocks, to connect them with
the beam, so that it should open and close the cocks as it moved up and
down, with the most perfect regularity. By this simple contrivance the
steam-engine for the first time became an automaton.
It was in repairing a working model of a steam-engine on Newcomen’s
principle for the lectures of the professor of natural philosophy
at the University of Glasgow, that James Watt directed his mind to
the prosecution of those inventions and beautiful contrivances, by
which he gave to senseless matter an almost instinctive power of
self-adjustment, with precision of action more than belongs to any
animated being, and which have rendered his name celebrated over the
world.
At the time of which we speak, Newcomen’s engine was of the last and
most approved construction. The moving power was the weight of the air
pressing on the upper surface of a piston working in a cylinder; steam
being employed at the termination of each downward stroke to raise the
piston with its load of air up again, and then to form a vacuum by its
condensation when cooled by a jet of cold water, which was thrown into
the cylinder when the admission of steam was stopped. Upon repairing
the model, Watt was struck by the incapability of the boiler to produce
a sufficient supply of steam, though it was larger in proportion to
the cylinder than was usual in working engines. This arose from the
nature of the cylinder, which being made of brass, a better conductor
of heat than cast-iron, and presenting, in consequence of its small
size, a much larger surface in proportion to its solid content than
the cylinders of working engines, necessarily cooled faster between
the strokes, and therefore at every fresh admission consumed a greater
proportionate quantity of steam. But being made aware of a much greater
consumption of steam than he had imagined, he was not satisfied without
a thorough inquiry into the cause. With this view he made experiments
upon the merits of boilers of different constructions; on the effect
of substituting a less perfect conductor, as wood, for the material of
the cylinder; on the quantity of coal required to evaporate a given
quantity of water; on the degree of expansion of water in the form of
steam: and he constructed a boiler which showed the quantity of water
evaporated in a given time, and thus enabled him to calculate the
quantity of steam consumed at each stroke of the engine. This proved to
be several times the content of the cylinder. He soon discovered that,
whatever the size and construction of the cylinder, an admission of
hot steam into it must necessarily be attended with very great waste,
if in condensing the steam previously admitted, that vessel had been
cooled down sufficiently to produce a vacuum at all approaching to a
perfect one. If, on the other hand, to prevent this waste, he cooled it
less thoroughly, a considerable quantity of steam remained uncondensed
within, and by its resistance weakened the power of the descending
stroke. These considerations pointed out a vital defect in Newcomen’s
engine; involving either a loss of steam, and consequent waste of fuel;
or a loss of power from the piston’s descending at every stroke through
a very imperfect vacuum.
It soon occurred to Watt, that if the condensation were performed in a
separate vessel, one great evil, the cooling of the cylinder, and the
consequent waste of steam, would be avoided. The idea once started, he
soon verified it by experiment. By means of an arrangement of cocks, a
communication was opened between the cylinder, and a distinct vessel
exhausted of its air, at the moment when the former was filled with
steam. The vapour of course rushed to fill up the vacuum, and was there
condensed by the application of external cold, or by a jet of water;
so that fresh steam being continually drawn off from the cylinder
to supply the vacuum continually created, the density of that which
remained might be reduced within any assignable limits. This was the
great and fundamental improvement.
Still, however, there was a radical defect in the atmospheric engine,
inasmuch as the air being admitted into the cylinder at every stroke,
a great deal of heat was abstracted, and a proportionate quantity of
steam wasted. To remedy this, Watt excluded the air from the cylinder
altogether; and recurred to the original plan of making steam the
moving power of the engine, not a mere agent to produce a vacuum. In
removing the difficulties of construction which beset this new plan,
he displayed great ingenuity and powers of resource. On the old plan,
if the cylinder was not bored quite true, or the piston not accurately
fitted, a little water poured upon the top rendered it perfectly
air-tight, and the leakage into the cylinder was of little consequence,
so long as the injection water was thrown into that vessel. But on the
new plan, no water could possibly be admitted within the cylinder;
and it was necessary, not merely that the piston should be air-tight,
but that it should work through an air-tight collar, that no portion
of the steam admitted above it might escape. This he accomplished by
packing the piston and the stuffing-box, as it is called, through which
the piston-rod works, with hemp. A further improvement consisted in
equalising the motion of the engine by admitting the steam alternately
above and below the piston, by which the power is doubled in the same
space, and with the same strength of material. The vacuum of the
condenser was perfected by adding a powerful pump, which at once drew
off the condensed and injected water, and with it any portion of air
which might find admission; as this would interfere with the action
of the engine if allowed to accumulate. His last great change was to
cut off the communication between the cylinder and the boiler, when a
portion only, as one-third or one-half, of the stroke was performed;
leaving it to the expansive power of the steam to complete it. By this,
œconomy of steam was obtained, together with the power of varying the
effort of the engine according to the work which it has to do, by
admitting the steam through a greater or smaller portion of the stroke.
These are the chief improvements which Watt effected at different
periods of his life. He was born June 19, 1736, at Greenock, where
he received the rudiments of his education. Having at an early age
manifested a partiality for the practical part of mechanics, he went in
his eighteenth year to London to obtain instruction in the profession
of a mathematical instrument-maker, but remained there little more than
a year, being compelled to return home on account of his health. In
1757, shortly after his return home, he was appointed instrument-maker
to the University of Glasgow, and accommodated with premises within the
precincts of that learned body. In 1763 he removed into the town of
Glasgow, intending to practise as a civil engineer. His first patent is
dated June 5, 1769, which parliament extended in 1775 for twenty-five
years in consideration of the national importance of the inventions,
and the difficulty and expense of introducing them to public notice.
He died at his house at Heathfield in the county of Stafford, on the
25th of August, 1819, at the advanced age of eighty-four, after having
realized an ample fortune, the well-earned reward of his industry and
ability.
To enter into the history of the various applications of the
steam-engine to the different branches of industry would carry us
beyond the bounds of this work. “To enumerate its present effects,”
says a well-known writer on the steam-engine[1], “would be to count
almost every comfort and every luxury of life. It has increased the sum
of human happiness, not only by calling new pleasures into existence,
but by so cheapening former enjoyments as to render them attainable by
those who before could never have hoped to share them: the surface of
the land, and the face of the waters are traversed with equal facility
by its power; and by thus stimulating and facilitating the intercourse
of nation with nation, and the commerce of people with people, it
has knit together remote countries by bonds of amity not likely to
be broken. Streams of knowledge and information are kept flowing
between distant centres of population, those more advanced diffusing
civilization and improvement among those that are more backward. The
press itself, to which mankind owes in so large a degree the rapidity
of their improvement in modern times, has had its power and influence
increased in a manifold ratio by its union with the steam-engine. It is
thus that literature is cheapened, and by being cheapened, diffused;
it is thus that reason has taken the place of force, and the pen has
superseded the sword; it is thus that war has almost ceased upon the
earth, and that the differences which inevitably arise between people
and people are for the most part adjusted by peaceful negotiation.”