THOMAS NEWCOMEN--THE ATMOSPHERIC ENGINE.
The invention of the steam-engine had advanced thus far with halting
steps. A new power had been discovered, but it was so dangerous and
unmanageable that it was still doubtful whether it could be applied to
any useful purpose. What was still wanting was an engine strong enough to
resist the internal pressure of highly-heated steam, and so constructed
as to work safely, continuously, and economically. Many attempts had been
made to contrive such a machine; but, as we have shown, the results were
comparatively barren. Savery’s small engine could raise water in moderate
quantities to limited heights; but the pumping of deep mines was beyond
its power. It could force water to a height of about sixteen fathoms; but
as the depth of mines at that time was from fifty to a hundred yards,
it was obviously incompetent for their drainage. It is true, Savery
proposed to overcome the difficulty by erecting a series of engines,
placed one over another in the shaft of the mine; but the expense of their
attendants, the great consumption of fuel, the cost of wear and tear, the
constant danger of explosion, and the risk of the works being stopped by
any one of the engines becoming temporarily deranged, rendered it clear
that the use of his engine for ordinary mining purposes was altogether
impracticable.
Such was the state of affairs when Thomas Newcomen of Dartmouth took up
the subject. Comparatively little is known of the personal history of
this ingenious man. Mechanical inventors excited little notice in those
days; they were looked upon as schemers, and oftener regarded as objects
of suspicion than of respect. Thomas Newcomen was by trade an ironmonger
and a blacksmith. The house in which he lived and worked stood, until
quite recently, in Lower Street, Dartmouth. Like many of the ancient
timber houses of that quaint old town, it was a building of singularly
picturesque appearance. Lower Street is very narrow; the houses in it are
tall and irregular, with overhanging peaked gable-ends. A few years since,
Newcomen’s house began to show indications of decay; the timber supports
were fast failing; and for safety’s sake it was determined to pull it to
the ground.
[Illustration: NEWCOMEN’S HOUSE, DARTMOUTH.
[By R. P. Leitch.][38]]
[38] Newcomen’s house occupies the centre of the above
engraving--the house with the peaked gable-end supported by
timbers.
The Newcomen family have long since become extinct in Dartmouth. They are
said to have left the place long ago, and gone northward; but we have been
unable to trace them. The Newcomens appear to have occupied a respectable
position in Dartmouth down to about the middle of the last century. Their
burying-place was in the north-side chapel of the fine old parish church
of the town, where several tablets are erected to their memory. Amongst
others, there is one to William Newcomin, Attorney-at-Law, who died
the 24th of August, 1745, aged 57, supposed to have been a brother, and
another of the same name, who died in 1787, aged 65, supposed to have been
a son of the ironmonger.
Thomas Newcomen was a man of strong religious feelings, and from an early
period of his life occupied his leisure in voluntary religious teaching.
He belonged to the sect of Baptists; and the place was standing until
recently in which he regularly preached. When he afterwards went into
distant parts of the country on engine business, he continued to devote
his Sundays to the same work. How he first came to study the subject of
steam is not known. Mr. Holdsworth says a story was current in Dartmouth
in his younger days, and generally believed, that Newcomen conceived
the idea of the motive power to be obtained from steam by watching the
tea-kettle, the lid of which would frequently rise and fall when boiling;
and, reasoning upon this fact, he contrived, by filling a cylinder with
steam, to raise the piston, and by immediately injecting some cold water,
to create a vacuum, which allowed the weight of the atmosphere to press
the piston down, and so give motion to a pump by means of a beam and
rods.[39]
[39] Pamphlet on ‘Dartmouth: the advantages of its Harbour as
a Station for Foreign Mail Packets, and a Short Notice of its
Ancient and Present Condition.’ By A. H. Holdsworth. London,
1841.
It is probable that Newcomen was well aware of the experiments of Savery
on steam while the latter was living at Modbury, about fifteen miles
distant. It will be remembered that Savery was greatly hampered in his
earlier contrivances by the want of skilled workmen; and as Newcomen had
the reputation of being one of the cleverest blacksmiths in the county,
it is supposed that he was employed to make some of the more intricate
parts of Savery’s engine. At all events, he could scarcely fail to hear
from the men of his trade in the neighbourhood, what his speculative
neighbour at Modbury was trying to compass in the invention of an engine
for the purpose of raising water by fire. He was certainly occupied in
studying the subject about the same time as Savery; and Switzer says he
was well informed that “Mr. Newcomen was as early in his invention as Mr.
Savery was in his, only the latter being nearer the Court, had obtained
the patent before the other knew it; on which account Mr. Newcomen was
glad to come in as a partner to it.”[40]
Another account[41] states that a draft of Savery’s engine having come
under Newcomen’s notice, he proceeded to make a model of it, which he
fixed in his garden, and soon found out its imperfections. He entered
into a correspondence on the subject with the learned and ingenious Dr.
Hooke, then Secretary to the Royal Society, a man of remarkable ingenuity,
and of great mechanical sagacity and insight. Newcomen had heard or read
of Papin’s proposed method of transmitting motive power to a distance by
creating a vacuum under a piston in a cylinder, and transmitting the power
through pipes to a second cylinder near the mine. Dr. Hooke dissuaded
Newcomen from erecting a machine on this principle, as a waste of time and
labour; but he added the pregnant suggestion, “could he (meaning Papin)
make a speedy vacuum under your piston, your work were done.”
[40] Switzer, ‘Introduction to a System of Hydrostatics and
Hydraulics,’ p. 342.
[41] Harris, ‘Lexicon Technicum.’
The capital idea thus cursorily thrown out--of introducing a moveable
diaphragm between the active power and the vacuum--set Newcomen at
once upon the right track. Though the suggestion was merely that of a
thoughtful bystander, it was a most important step in the history of the
invention, for it contained the very principle of the atmospheric engine.
Savery created his vacuum by the condensation of steam in a closed vessel,
and Papin created his by exhausting the air in a cylinder fitted with a
piston, by means of an air-pump. It remained for Newcomen to combine the
two expedients--to secure a sudden vacuum by the condensation of steam;
but, instead of employing Savery’s closed vessel, he made use of Papin’s
cylinder fitted with a piston. After long scheming and many failures,
he at length succeeded, in the year 1705,[42] in contriving a model that
worked with tolerable precision; after which he sought for an opportunity
of exhibiting its powers in a full-sized working engine. It ought to be
mentioned, that in the long course of experiments conducted by Newcomen
with the object of finding out the new motive power, he was zealously
assisted throughout by one John Calley, a glazier of Dartmouth, of whom
nothing further is known than that he was Newcomen’s intimate friend,
of the same religious persuasion, and afterwards his partner in the
steam-engine enterprise.
[42] It has been stated that Newcomen took out a patent for his
invention in 1705; but this is a mistake, as no patent was
ever taken out by Newcomen. It is supposed that Savery, having
heard of his invention, gave him notice that he would regard
his method of producing a speedy vacuum by condensation, as
an infringement of his patent, and that Newcomen accordingly
agreed to give him an interest in the new engine during the
term of Savery’s patent. It will, however, be observed that
the principle on which Newcomen’s engine worked was entirely
different from that of Savery.
Newcomen’s engine may be thus briefly described:--The steam was generated
in a separate boiler, as in Savery’s engine, from which it was conveyed
into a vertical cylinder underneath a piston fitting it closely, but
moveable upwards and downwards through its whole length. The piston was
fixed to a rod, which was attached by a joint or a chain to the end of
a lever vibrating upon an axis, the other end being attached to a rod
working a pump. When the piston in the cylinder was raised, steam was let
into the vacated space through a tube fitted into the top of the boiler,
and mounted with a stopcock. The pump-rod at the further end of the lever
being thus depressed, cold water was applied to the sides of the cylinder,
on which the steam within it was condensed, a vacuum was produced, and the
external air, pressing upon the top of the piston, forced it down into
the empty cylinder. The pump-rod was thereby raised; and the operation
of depressing and raising it being repeated, a power was thus produced
which kept the pump continuously at work. Such, in a few words, was the
construction and action of Newcomen’s first engine.
It will thus be observed that this engine was essentially different in
principle from that of Savery. While the latter raised water partly by
the force of steam and partly by the pressure of the atmosphere, that
of Newcomen worked entirely by the pressure of the atmosphere, steam
being only used as the most expeditious method of producing a vacuum.
The engine was, however, found to be very imperfect. It was exceedingly
slow in its motions; much time was occupied in condensing the contained
steam by throwing cold water on the outside of the cylinder; and as the
boiler was placed immediately under the cylinder, it was not easy to
prevent the cold water from splashing it, and thus leading to a further
loss of heat. To remedy these imperfections, Newcomen and Calley altered
the arrangement; and, instead of throwing cold water on the outside of
the cylinder, they surrounded it with cold water. But this expedient was
also found inconvenient, as the surrounding water shortly became warm,
and ceased to condense until replaced by colder water; but the colder it
was the greater was the loss of heat by condensation, before the steam
was enabled to fill the cylinder again on each ascent of the piston.
Clumsy and comparatively ineffective though the engine was in this form,
it was, nevertheless, found of some use in pumping water from mines.
In 1711 Newcomen and Calley made proposals to the owners of a colliery
at Griff, in Warwickshire, to drain the water from their pits, which
until then had been drained by the labour of horses; but, the owners not
believing in the practicability of the scheme, their offer was declined.
In the following year, however, they succeeded in obtaining a contract
with Mr. Back, for drawing the water from a mine belonging to him near
Wolverhampton. The place where the engine was to be erected being near to
Birmingham, the ironwork, the pump-valves, clacks, and buckets, were for
the most part made there, and removed to the mine, where they were fitted
together. Newcomen had great difficulty at first in making the engine go;
but after many laborious attempts he at last partially succeeded. It was
found, however, that the new method of cooling the cylinder by surrounding
it with cold water did not work so well in practice as had been expected.
The vacuum produced was very imperfect, and the action of the engine was
both very slow and very irregular.
While the engine was still in its trial state, a curious accident occurred
which led to another change in the mode of condensation, and proved of
essential importance in establishing Newcomen’s engine as a practicable
working power. The accident was this: in order to keep the cylinder as
free from air as possible, great pains were taken to prevent it passing
down by the side of the piston, which was carefully wrapped with cloth or
leather; and, still further to keep the cylinder air-tight, a quantity
of water was kept constantly laying on the upper side of the piston. At
one of the early trials the inventors were surprised to see the engine
make several strokes in unusually quick succession; and on searching for
the cause, they found it to consist in _a hole in the piston_, which had
let the cold water in a jet into the inside of the cylinder, and thereby
produced a rapid vacuum by the condensation of the contained steam. A new
light suddenly broke upon Newcomen. The idea of condensing by injection
of cold water directly into the cylinder, instead of applying it on the
outside, at once occurred to him; and he proceeded to embody the expedient
which had thus been accidentally suggested, as part of his machine. The
result was the addition of the injection-pipe, through which, when the
piston was raised and the cylinder was full of steam, a jet of cold water
was thrown in, and the steam being suddenly condensed, the piston was at
once driven down by the pressure of the atmosphere.
An accident of a different kind shortly after led to the improvement of
Newcomen’s engine in another respect. To keep it at work, one man was
required to attend the fire, and another to turn alternately the two
cocks, one admitting the steam into the cylinder, the other admitting
the jet of cold water to condense it. The turning of these cocks was easy
work, usually performed by a boy. It was, however, a very monotonous duty,
though requiring constant attention. To escape the drudgery and obtain an
interval for rest, or perhaps for play, a boy named Humphrey Potter, who
turned the cocks, set himself to discover some method of evading his task.
He must have been an ingenious boy, as is clear from the arrangement he
contrived with this object. Observing the alternate ascent and descent
of the beam above his head, he bethought him of applying the movement
to the alternate raising and lowering of the levers which governed the
cocks. The result was the contrivance of what he called the _scoggan_,[43]
consisting of a catch worked by strings from the beam of the engine. This
arrangement, when tried, was found to answer the purpose intended. The
action of the engine was thus made automatic; and the arrangement, though
rude, not only enabled Potter to enjoy his play, but it had the effect of
improving the working power of the engine itself; the number of strokes
which it made being increased from six or eight to fifteen or sixteen in
the minute. This invention was afterwards greatly improved by Mr. Henry
Beighton, of Newcastle-on-Tyne, who added the plug-rod and hand-gear. He
did away with the catches and strings of the boy Potter’s rude apparatus,
and substituted a rod suspended from the beam, which alternately opened
and shut the tappets attached to the steam and injection cocks.
[Illustration: NEWCOMEN’S ENGINE.[44]]
[43] _Scogging_ is a north country word, meaning skulking one’s
work, from which probably the boy gave the contrivance its name.
Potter, however, grew up to be a highly-skilled workman. He went
abroad about the year 1720, and erected an engine at a mine in
Hungary, described by Leupold in his ‘Theatrum Machinarum,’ with
many encomiums upon Potter, who was considered the inventor.
[44] The illustration shows the several parts of Newcomen’s
atmospheric engine. _a_ is the boiler; _b_, the piston moving
up and down; _c_, the cylinder; _d_, a pipe proceeding from the
top of the boiler, and inserted into the bottom of the cylinder,
having a cock, _e_, to interrupt the flow of steam at pleasure;
_f_, cold-water cistern, from which the cold water is conveyed
by the pipe _g_, called the injection-pipe, and thrown in a jet
into the cylinder, _b_, on turning the injection-cock, _h_;
the snifting-valve, _i_, enables the air to escape from the
cylinder, while the siphon-pipe, _j_, enables the condensed
steam to flow from the same cavity in the form of water; _k_,
the main lever beam; _l_, the counterpoise or weight hung on the
balance-beam, or on _m_, the pump-rod which works the pump, _n_.
Thus, step by step, Newcomen’s engine grew in power and efficiency,
and became more and more complete as a self-acting machine. It will be
observed that, like all other inventions, it was not the product of any
one man’s ingenuity, but of many. One contributed one improvement, and
another another. The essential features of the atmospheric engine were
not new. The piston and cylinder had been known as long ago as the time
of Hero. The expansive force of steam and the creation of a vacuum by its
condensation had been known to the Marquis of Worcester, Savery, Papin,
and many more. Newcomen merely combined in his machine the result of their
varied experience, and, assisted by the persons who worked with him, down
to the engine-boy Potter, he advanced the invention several important
stages; so that the steam-engine was no longer a toy or a scientific
curiosity, but had become a powerful machine capable of doing useful work.
The comparative success which attended the working of Newcomen’s first
engine at the colliery near Wolverhampton, shortly induced other owners of
coal-mines to adopt it. There were great complaints in the north, of the
deeper mines having become unworkable. All the ordinary means of pumping
them clear of water had failed. In their emergency, the colliery-owners
called Newcomen and Calley to their aid. They were invited down to
Newcastle-upon-Tyne, in the neighbourhood of which town they erected their
second and third engines. They were next summoned to Leeds, and erected
their fourth engine at Austhorpe, in 1714. It was the sight of this engine
at work which first induced Smeaton, when a boy, to turn his attention to
mechanics, and eventually led him to study the atmospheric-engine, with a
view to its improvement. The cylinder of the engine erected at Austhorpe,
like those which had preceded it, was about 23 inches in diameter, and
made about fifteen strokes a minute. The pumps, which were in two lifts,
and of 9 inches bore, drew the water from a depth of 37 yards. The
patentees had 250_l._ a year for working and keeping the engine in order.
Calley superintended its erection, and afterwards its working; but he did
not long survive its completion, as he died at Austhorpe in 1717.
The next engines were erected by Newcomen in Cornwall, where there was as
great a demand for increased pumping-power as in any of the collieries of
the north. The first of Newcomen’s construction in Cornwall was erected
in 1720, at the Wheal Fortune tin mine, in the parish of Ludgvan, a
few miles north-east of Penzance. The mine was conducted by Mr. William
Lemon, the founder of the fortunes of the well-known Cornish family. He
was born in a humble station in life, from which he honourably raised
himself by his great industry, ability, and energy. He began his career
as a mining-boy; was at an early age appointed one of the managers of a
tin-smelting house at Chiandower, near Penzance; and after the experience
gained by him in that capacity he engaged in the working of the Wheal
Fortune mine. With the help of Newcomen’s engine, the enterprise proved
completely successful; and after realising a considerable sum he removed
to Truro, and began working the great Gwennap mines on such a scale as
had never before been known in Cornwall.[45]
[45] Mr. Lemon eventually became the principal merchant and
tin-smelter of Cornwall. Mr. Davies Gilbert says:--“The energies
of his mind were not limited to these undertakings, great
though they were. He cultivated a taste for literature, and,
which is extremely unusual, acquired, amidst business, and at a
middle age, the power of reading the classic authors in their
original language.... He was distinguished in his district as
“the great Mr. Lemon,” but such were the impressions of his
abilities, his exertions, and general merit, that a progress so
rapid and unexampled does not appear to have excited envy, or
any of those bad passions which usually alloy the enjoyment of
prosperity.”--‘History of Cornwall,’ ii. 84.
The Wheal Fortune engine was on a larger scale than any that had yet been
erected, the cylinder being 47 inches in diameter, making about fifteen
strokes a minute. It drew about a hogshead of water at each stroke, from
a pump 30 fathoms deep, through pit-barrels 15 inches in diameter, and
its performances were on the whole regarded as very extraordinary. The
principal objection to its use consisted in the very large quantity of
coal that it consumed and the heavy cost of maintaining it in working
order. There was a great waste, especially in boilers, the making of which
was then ill understood. Smeaton relates that in the course of four years’
working of the first Austhorpe engine, not fewer than four boilers were
burnt out. The Wheal Fortune engine, however, answered its purpose. It
kept down the water sufficiently to enable Mr. Lemon to draw up his tin,
and on leaving the mine, he took with him to Truro a clear sum of ten
thousand pounds. The engine-house is now in ruins, and presents a highly
picturesque appearance, as seen from the heights of Trewal, reminding one
of a Border Peel rather than of a mining engine-house.
[Illustration: RUINS OF WHEAL FORTUNE.
[By R. P. Leitch.]]
Another of Newcomen’s engines was erected about the same time at the
Wheal Rose mine, a few miles north of Redruth. The engineer appointed
to superintend its erection was Joseph Hornblower, who came from
Staffordshire for the purpose about the year 1725. Mr. Cyrus Redding, one
of Hornblower’s descendants, says, “how he became in any way connected
with Newcomen must have arisen from the latter being at Bromsgrove, when
he visited Mr. Potter, who got him to build one of his newly-invented
engines at Wolverhampton in 1712.”[46] Another engine was afterwards
erected by Hornblower at Wheal Busy, or Chacewater, and a third at
Polgooth--all rich and well-known mines in Cornwall.
[Illustration: POLGOOTH.]
[46] “It may be interesting to know that it required three hands
to work Newcomen’s first engines. I have heard it said that
when the engine was stopped, and again set at work, the words
were passed “Snift Benjy!” “Blow the fire, Pomery!” “Work
away, Joe!” The last let in the condensing water. Lifting the
condensing clack was called “snifting,” because on opening
the valve, the air rushing through it made a noise like a man
snifting. The fire was increased through artificial means by
another hand, and all being ready, the machine was set in motion
by a third.”--Cyrus Redding, ‘Yesterday and To-day.’ London,
1863. The “snifting clack” was a valve in the cylinder opening
outwards, which permitted the escape of air or permanently
elastic fluid, which could not be condensed by cold and run off
through the eduction-pipe.
Though the use of Newcomen’s engine rapidly extended, nothing is known of
the man himself during this time. All over the mining districts his name
was identified with the means employed for pumping the mines clear of
water, and thereby enabling an important branch of the national industry
to be carried on; but of Newcomen’s personal history, beyond what has
been stated above, we can gather nothing. It is not known when or where
he died, whether rich or poor. The probability is that, being a person
of a modest and retiring disposition, without business energy, and having
secured no protection for his invention, it was appropriated and made use
of by others, without any profit to him, whilst he quietly subsided into
private life. It is supposed that he died at Dartmouth about the middle
of last century; but no stone marks the place where he was laid. The
only memorial of Newcomen to be found at his native place is the little
steam-boat called by his name, which plies between Totness and Dartmouth.
During Newcomen’s lifetime the proposal was revived of applying the
steam-engine to the propelling of ships. Since Papin’s time nothing
had been accomplished in this direction. Now that the steam-engine was
actively employed in pumping mines, it was natural enough that the idea
should be revived of applying it to navigation. The most enthusiastic
advocate of the new power was Jonathan Hulls, a native of Campden, in
Gloucestershire, where he was born in 1699. He married a wife in 1719,
before he was out of his teens; an act of indiscretion in which, however,
he had the example of one no less distinguished than Shakspeare. Living
as he did in an inland country place, it seems remarkable that he should
have directed his attention to the subject of steam-navigation. We
find him making experiments with models of boats on the river Avon, at
Evesham, and in course of time he duly matured his ideas and embodied
them in his patent of 1736.[47] He proposed to place a Newcomen engine
on board a tow-boat, and by its means to work a paddle-wheel placed at
the stern. His method of converting the rectilinear motion of his piston
into a rotary one was ingenious, but, like Savery, he missed the crank
on the paddle-shaft, and many years passed before this simple expedient
was adopted.[48] “The work to be done by this machine,” said he, “will be
upon particular occasions, when all other means yet found out are wholly
insufficient. How often does a merchant wish that his ship were on the
ocean, when, if she were there, the wind would serve tolerably well to
carry him on his intended voyage, but does not serve at the same time to
carry him out of the river he happens to be in, which a few hours’ work
of the machine would do. Besides, I know engines that are driven by the
same power as this is, where materials for the purpose are dearer than in
any navigable river in England; therefore experience demonstrates that the
expense will be but a trifle to the value of the work performed by those
sort of machines, which any person that knows the nature of those things
may easily calculate.” His treatise was illustrated by a drawing, of which
the following is a copy on a reduced scale.
[47] In 1737 he published a Treatise on the subject entitled, ‘A
description and Draught of a new-invented Machine for carrying
Vessels or Ships out of or into any Harbour, Port, or River,
against Wind or Tide, and in a Calm,’ by Jonathan Hulls.
[Illustration: JONATHAN HULLS’S STEAM-BOAT.]
[48] In describing his mode of obtaining rotary motion by ratchet
wheels, a weight, and ropes, Hulls states that he uses two
axes, one behind the other, each of which is essential to the
object; and he then adds, that when his tow-boat is to be used
in shallow rivers, the machine works by two cranks fixed to the
hindermost axis; to which cranks are fixed two shafts (or poles)
of proper length to reach the bottom of the river, and which
move alternately forward _from the motion of the wheels by which
the vessel is carried on_: so that the cranks, as described
by Hulls, receive rotary motion from the axis on which they
are placed, and do not, as has been erroneously stated, impart
that motion to it.--Bennet Woodcroft, ‘Sketch of the Origin and
Progress of Steam Navigation.’ London, 1848.
The inventor, aware of the novelty of his proposal and of the readiness of
the public to ridicule novelties, deprecated rash censure of his project,
and only claimed for it a fair and unprejudiced trial. In order to exhibit
the powers of his steam-boat, he constructed an engine in 1737, and had it
fixed on board a little vessel for trial in the river Avon at Evesham. The
trial was not satisfactory, and the engine was taken on shore again. “A
failure! A failure!” cried the spectators, who stigmatised the projector
as an ass. The prophet had, indeed, no honour whatever in his own country.
Long after his steam-boat experiment had been forgotten, these lines about
him were remembered:--
“Jonathan Hull,
With his paper skull,
Tried hard to make a machine
That should go against wind and tide:
But he, like an ass,
Couldn’t bring it to pass,
So at last was ashamed to be seen.”[49]
Not much more is known of Jonathan Hulls’s history. In 1754 he published,
in conjunction with two others, a treatise on ‘The Art of Measuring
made Easy, by the help of a new Sliding-rule;’ and shortly after ‘The
Malt-maker’s Instructor;’ but nothing more was heard of Jonathan Hulls’s
steam-boat.
[49] There are several versions of the same satire current to this
day in the villages of Campden and Hanging Aston.
We return to the Newcomen engine, which became increasingly employed as
a pumping power in all the mining districts. Borlase, writing in 1758,
says that “fire-engines” were then in regular use at North Downs near
Redruth, Pitt-louarn, Polgooth, Wheal-rith, Pool, Dolcoath, Herland, and
many other places.[50] Indeed there was scarcely a tin or copper mine of
any importance in Cornwall that had not one or more of Newcomen’s engines
at work. They were also in general use in Staffordshire, Yorkshire,
Lancashire, and Northumberland. In the latter counties, where they
were principally used for pumping water out of the coal mines, fuel was
ready at hand, cheap and abundant. But in Cornwall it was otherwise. The
coal had to be brought thither from a great distance, partly by sea and
partly by land, and the cost of carriage was very heavy. It, therefore,
became an object of much importance to reduce the consumption of fuel,
to prevent the profits of the mines being absorbed by the heavy cost of
working the pumps. This, indeed, was the great objection to Newcomen’s
engine, especially in Cornwall. The consumption of fuel at some mines
was so enormous, that it was doubtful whether the cost of steam did not
exceed that of an equal amount of horse power, and it became more and
more difficult to realise even a bare margin of profit. The two engines at
Wheal Rose and Wheal Busy, near Chacewater, of 66 and 72 inches diameter,
consumed each about thirteen tons of coal daily. To relieve the mining
interest, in some measure, from this charge, government allowed a drawback
of five shillings a chaldron on coal; but in some cases this was found
insufficient, and it began to be complained that the consumption of coal
was so great, that the mines were barely paying.
[50] Borlase, ‘Natural History of Cornwall,’ p. 175.
Invention, however, was constantly at work, and new improvements were
from time to time introduced, with the object of economising fuel and
increasing the efficiency of the engine. Among the ingenious men who
devoted themselves to this work, were Payne, Brindley, and Smeaton. Of
these, the last especially distinguished himself by his improvements of
the Newcomen engine, which he may be said to have carried to the highest
perfection of which it was capable. His famous Chacewater engine was
the finest and most powerful work of the kind which had until then been
constructed, and it remained unrivalled until superseded by the invention
of Watt, to whose life and labours we now proceed to direct the attention
of the reader.
[Illustration: DARTMOUTH, FROM THE HARBOUR.
[By R. P. Leitch.]]
JAMES WATT:
HIS BOYHOOD AND EARLY LIFE: MECHANICAL INSTRUMENT MAKER, SURVEYOR, AND
INVENTOR.
[Illustration: GREENOCK AND THE CLYDE, 1865.
[By R. P. Leitch, after a sketch by J. S. Smiles.]]
[Illustration: GREENOCK HARBOUR, 1768.
[Fac-simile of an old print.]]