James Watt, the son of a merchant, was born at Greenock, in Scotland,
on the 19th of January, 1736. He received the first part of his
education at a school in his native place, and completed it at home,
by his own diligence. The science of mechanics, for which he
afterwards became so famous, formed, at an early age, his favorite
study; and, in conformity with his desire, he was, at the age of
eighteen, apprenticed to a mathematical instrument-maker, in London.
The bad state of his health, however, which had before retarded his
progress at school, compelled him to return, after a year’s stay in
the metropolis, to Scotland. This was all the instruction he ever
received in the business for which he was intended, yet he must have
attained considerable skill, as, in 1757, he, at the recommendation of
some relations, commenced the practice of it, at Glasgow, and was
immediately appointed mathematical instrument-maker to the college. He
continued to hold this situation till 1763, when he married, left his
apartments in the university, for a house in the town of Glasgow, and
commenced the profession of a general engineer. He soon acquired a
high reputation; and in making surveys and estimates for canals,
harbors, bridges, and other public works, was as extensively employed
in his own country, as Brindley had been in England.
His attention to the employment of steam, as a mechanical agent, had
been, in the first instance, excited by witnessing some experiments of
his friend Mr. John (afterwards Dr.) Robison, and he had also made
some experiments himself, with a view of ascertaining its expansive
force. It was not, however, till 1763-4 that he began to devote
himself seriously to the investigation of the properties of steam, and
to ascertain those results upon which his fame was to be founded. An
examination of Newcomen’s engine, a model of which had been sent him
to repair, revived all his former impressions respecting the radical
imperfections of the atmospheric machine, to the improvements of which
he now ardently devoted himself. One of his first discoveries was,
that the rapidity with which water evaporates, depends simply upon the
quantity of heat which is imbibed, and this again on the extent of the
surface of the vessel containing the water, exposed to the fire. He
ascertained also the quantity of coals necessary for the evaporation
of any given quantity of water, the heat at which it boils under
various pressures, and many other particulars never before accurately
determined.
[Illustration: VIEW ON GRAND RIVER, OHIO.]
[Illustration: BRIDGE, CONEAUT RIVER.]
He now proceeded to attempt a remedy of the two grand defects of
Newcomen’s engine――the necessity of cooling the cylinder before every
stroke of the piston, by the water injected into it; and the
non-employment of the machine, for a moving power, of the expansive
force of the steam. On account of the first defect, a much more
powerful application of heat than would otherwise have been requisite
was demanded for the purpose of again heating the cylinder, when it
was to be refilled with steam. To keep this vessel, therefore,
permanently hot, was the grand desideratum; and Watt at length hit
upon an expedient equally simple and successful. His plan was to
establish a communication, by an open pipe, between the cylinder and
another vessel, the consequence of which would be, that when the steam
was admitted into the former, it would flow into the latter, so as to
fill that also. Supposing, then, that the steam should here only be
condensed, by being brought into contact with cold water, or any other
convenient means, a vacuum would be produced, into which, as a vent,
more steam would immediately rush from the cylinder; this steam would
also be condensed; and so the process would go on, till all the steam
had left the cylinder, and a perfect vacuum had been effected in that
vessel, without so much as a drop of cold water having touched or
entered it. The separate vessel alone, or the condenser, would be
cooled by the water used to condense the steam; which, instead of
being an evil, would tend to quicken and promote the condensation.
Experiments fully confirmed Watt in these views; and the consequence
was, not only a saving of three-fourths of the fuel formerly required
to feed the engine, but a considerable increase of its power.
In overcoming this difficulty, Watt was conducted to another
improvement, which effected the complete removal of what we have
described as the second radical imperfection of Newcomen’s engine,
namely, its non-employment, for a moving power, of the expansive force
of the steam. The effectual way, it occurred to him, of preventing any
air from escaping into the parts of the cylinder below the piston,
would be to dispense with the use of that element above the piston,
and to substitute there likewise the same contrivance as below, of
alternate steam and a vacuum. This was to be accomplished by merely
opening communications from the upper part of the cylinder to the
boiler, on the one hand, and the condenser on the other; and forming
it, at the same time, into an air-tight chamber, by means of a cover,
with only a hole in it to admit the rod or shank of the piston, which
might, besides, without impeding its freedom of action, be padded with
hemp, the more completely to exclude the air. It was so contrived,
accordingly, by a proper arrangement of the cocks, and the machinery
connected with them, that while there was a vacuum in one end of the
cylinder, there should be an admission of steam into the other; and
the steam so admitted now served, not only by its susceptibility of
sudden condensation, to create the vacuum, but also, by its expansive
force, to impel the piston.
These were the principal fundamental improvements in an engine, which
has since been brought to such perfection of action and power, as to
form one of the most triumphant eras in the history of human
ingenuity. Instead of entering into all the subsequent contrivances
which Watt invented, we cannot give a better idea of his splendid
success, than by quoting the language of a recent writer. ‘In the
present state of the engine, it appears a thing almost endowed with
intelligence. It regulates, with perfect accuracy and uniformity, the
number of its strokes in a given time, counting or recording them,
moreover, to tell how much work it has done, as a clock records the
beats of its pendulum; it regulates the quantity of steam admitted to
work; the briskness of the fire, the supply of water to the boiler;
the supply of coals to the fire; it opens and shuts its valves with
absolute precision as to time and manner; it oils its joints; it takes
out any air which may accidentally enter into parts which should be
vacuous; and, when anything goes wrong, which it cannot of itself
rectify, it warns its attendants by ringing a bell; yet, with all
these talents and qualities, and even when exerting the power of six
hundred horses, it is obedient to the hand of a child; its aliment is
coal, wood, charcoal, or other combustible; it consumes none while
idle; it never tires, and wants no sleep; it is not subject to malady
when originally well made, and only refuses to work when worn out with
age; it is equally active in all climates, and will do work of any
kind; it is a water-pumper, a miner, a sailor, a cotton-spinner, a
weaver, a blacksmith, a miller, etc., etc.; and a small engine, in the
character of a steam pony, may be seen dragging after it, on a
railroad, a hundred tons of merchandise, or a regiment of soldiers,
with greater speed than that of our fleetest coaches. It is the king
of machines; and a permanent realization of the genii of eastern
fable, whose supernatural powers were occasionally at the command of
man.’
Watt had, however, another difficulty to surmount; that of bringing
his invention into practice. Having no pecuniary resources of his own,
he applied to Dr. Roebuck, who had just established the Carron iron
works, to advance the requisite funds; which he consented to do, on
having two-thirds of the profits made over to him. A patent was
accordingly obtained in 1769, and an engine soon after erected; but
the failure of Dr. Roebuck thwarted the project, for a time, and the
subject of our memoir returned to his business of a civil engineer. At
length, in 1774, a proposal was made to him, to remove to Birmingham,
and enter into partnership with the celebrated hardware manufacturer,
Mr. Boulton. Dr. Roebuck’s share of the patent was shortly afterwards
transferred to Mr. Boulton, and the firm of Boulton and Watt commenced
the business of making steam-engines, in the year 1775. From this
date, Mr. Watt obtained from parliament an extension of his patent for
twenty-five years, in the course of which he added several new
improvements to the mechanism of his engine. In particular, he exerted
himself, for many years, in contriving the best methods of making the
action of the piston communicate a rotatory motion in various
circumstances; and, between the years 1781 and 1785, he took out four
different patents, for inventions relating to this object.
The invention of Watt was fully appreciated in the scientific world.
In 1785, he was elected a fellow of the Royal Society; in 1806, LL.D.,
by the University of Glasgow; and, in 1808, a member of the French
Institute. He died on the 25th of August, 1819, in the eighty-fourth
year of his age, leaving behind him a name that will descend to
posterity, in connexion with an invention that has already gone far to
revolutionize the whole domain of human industry. ‘The trunk of an
elephant,’ it has been truly said of this machine, ‘that can pick up a
pin, or rend an oak, is as nothing to it. It can engrave a seal, and
crush masses of obdurate metal like wax before it; draw out, without
breaking, a thread as fine as gossamer; and lift a ship of war, like a
bauble, in the air. It can embroider muslin, and forge anchors; cut
steel into ribands, and impel loaded vessels against the fury of the
winds and the waves.’