in one of the battles of Montrose. The victorious party, not
thinking death a sufficient expiation for the political opinions in
support of which he had fought and bled, punished him in the person
of his son, by confiscating his little property. Thomas Watt, the
son, thus deprived of support, was received by distant relations,
and, for a time, applied himself to study, by which he was enabled,
after the restoration of tranquillity, to establish himself at
Greenock as a teacher of practical mathematics and navigation. He
resided in the burgh or barony of Crawford's Dyke, and attained a
position of sufficient respectability to be elected to the office of
baron-baillie, or chief magistrate, and died in 1734, at the
advanced age of ninety-two years.
Thomas Watt had two sons. The elder, John, adopted the profession
of his father, and was a teacher of mathematics and navigation at
Glasgow: he died in 1737, at the age of fifty years. The second
son, James, the father of the celebrated engineer, was, during a
quarter of a century, treasurer of the town council of Greenock,
and a local magistrate. He was remarked for the ardent zeal and
enlightened spirit with which he discharged his public duties. His
business was that of a ship-chandler, builder, and general
merchant; but, unhappily, notwithstanding his active industry, he
lost, in the decline of his life, by unsuccessful commercial
speculations, a part of the property which he had so honourably
acquired. He died in 1782, at the age of eighty-four years.
JAMES WATT, to whom the world is so largely indebted for the
extension and improvement of steam power, had from his birth an
extremely delicate constitution. From his mother, [Pg078] whose
family name was Muirhead, he received his first lessons in
reading, and he learned from his father writing and arithmetic.
Although he was entered as a pupil in the grammar school of
Greenock, yet such was his delicate state of health, that his
attendance there was so interrupted by constant indisposition that
he could derive but little benefit from the opportunities of
instruction which it afforded. For a great period of the year he
was confined to his room, where he devoted himself to study
without the aid of instruction. It was in the retirement of the
sick chamber that the high intellectual faculties of Watt, which
were destined to produce such precious fruits, began to unfold
themselves. He was too sickly to be subjected to the restraints
which the business of education usually imposes on children. His
parents, therefore, found it necessary to leave him at liberty to
choose his occupations and amusements. The following anecdotes
will show the use he made of this freedom.
A friend of his father found the boy one day stretched upon the
hearth tracing with chalk various lines and angles. "Why do you
permit this child," said he, "to waste his time so; why not send
him to school?" Mr. Watt replied, "You judge him hastily; before
you condemn us, ascertain how he is employed." On examining the
boy, then six years of age, it was found that he was engaged in
the solution of a problem of Euclid!
Having observed the tendency of his son's mind, Mr. Watt placed at
his disposal a collection of tools. These he soon learned to use
with the greatest skill. He took to pieces and put together, again
and again, all the children's toys which he could procure; and he
was constantly employed in making new ones. Subsequently he used
his tools in constructing a little electrical machine, the sparks
proceeding from which became a great subject of amusement to all
the playfellows of the poor invalid.
Though endowed with great retentive powers, Watt would probably
never have figured among the prodigies of a common school: he would
have been slow to commit his lessons to memory, from the repugnance
which he would feel to repeat like a parrot anything which he did
not perfectly [Pg079] understand. The natural tendency of his mind
to meditate on whatever came before it, would give him, to
superficial observers, the appearance of dullness. Happily, however,
he had a parent who was sufficiently clear-sighted, and who
entertained high hopes of the growing faculties of his son. More
distant and less sagacious relations were not so sanguine. One day
Mrs. Muirhead, the aunt of the boy, reproaching him for what she
conceived to be listless idleness, desired him to take a book and
occupy himself usefully. "More than an hour has now passed away,"
said she, "and you have not uttered a single word. Do you know what
you have been doing all this time? You have taken off, and put on,
repeatedly, the lid of the tea-pot; you have been holding the
saucers and the spoons over the steam, and you have been
endeavouring to catch the drops of water formed on them by the
vapour. Is it not a shame for you to waste your time so?"
Mrs. Muirhead was little aware that this was the first experiment
in the splendid career of discovery which was subsequently to
immortalise her little nephew. She did not see, as we now can, in
the little boy playing with the tea-pot, the great engineer
preluding to those discoveries which were destined to confer on
mankind benefits so inestimable.
One of the social qualities of mind which was remarkable
throughout his life, was the singular felicity and grace with
which he related anecdotes. This power was manifested even in his
earliest childhood. The following is an extract from a letter
written by Mrs. Marion Campbell, his cousin, and the playfellow of
his childhood:—
"He was not fourteen when his mother brought him to Glasgow to
visit a friend of hers; his brother John accompanied him. On Mrs.
Watt's return to Glasgow, some weeks after, her friend said, 'You
must take your son James home; I cannot stand the degree of
excitement he keeps me in; I am worn out for want of sleep. Every
evening before ten o'clock, our usual hour of retiring to rest, he
contrives to engage me in conversation, then begins some striking
tale, and, whether humorous or pathetic, the interest is so
overpowering that the family all listen to him with breathless
attention, and hour after hour strikes unheeded.'" [Pg080]
Watt had a younger brother, John, who was subsequently lost by
shipwreck, in a voyage from Scotland to the United States. This lad,
having determined on following the business of his father, left James
more completely at liberty to choose his own occupation. But such a
choice was difficult for a student who commanded equal success in
every thing to which he directed his attention.
The excursions which he was in the habit of making on the Scottish
mountains surrounding Loch Lomond, naturally directed his
attention to botany and mineralogy, in each of which he attained
considerable knowledge. His love of anecdote and romance was
likewise gratified by the scenery which he enjoyed in these walks;
and the traditions and popular songs with which they made him
acquainted. When from ill-health, as constantly happened, he was
confined to the house, he devoted himself to chemistry, natural
philosophy, and even to medicine and surgery. In chemistry he
acquired some experimental skill, and studied with eager zeal the
elements of natural philosophy by S'. Gravesande. His own unhappy
maladies prompted him to read works on surgery and medicine; and
to such an extent did the activity of his mind impel him on these
subjects, that he was found one day dissecting, in his room, the
head of a child, who had died of some unknown disease, with a view
to ascertain the cause of its death.
In 1775, at the age of nineteen, at the recommendation of Dr.
Dick, professor of natural philosophy in the university of
Glasgow, he went to London, where he employed himself in the house
of Mr. John Morgan, a mathematical instrument maker, in Finch
Lane, Cornhill, to whom he apprenticed himself for three years. He
remained, however, only a year, at the expiration of which
(probably owing to his delicate state of health) he was released
from his apprenticeship, and returned to Glasgow, with the
intention of establishing himself in business as an optician and
mathematical instrument maker. In the fulfilment of this
intention, however, he was obstructed by the interposition of the
Corporation of Trades in that town, who regarded him as an
intruder, not qualified by the necessary apprenticeship to carry
on business. All means of conciliation being [Pg081] exhausted,
the Professors of the University interfered, and gave him the use
of three apartments within the college, for carrying on his
business, and likewise appointed him mathematical instrument maker
to the University. Soon afterwards the opposition of the local
trades seems to have given way, and he opened a shop in Glasgow
for the sale of mathematical instruments.
After the celebrity at which he has arrived, it will be easily
believed that every trace of his earlier connection with Glasgow
college is carefully cherished. There are accordingly preserved at
that place little instruments and pieces of apparatus of exquisite
workmanship, which were executed entirely by the hand of Watt, at
a time when he was not in a condition to command the aid of
workmen under him.
At the time of obtaining this appointment in the University, Watt
was in his twenty-first year. His natural talents and winning
manners were speedily the means of gaining for him the esteem and
friendship of all those eminent persons connected at the time with
that university whose regard was most valued. Among these the
earliest of his friends and patrons were—ADAM SMITH, the author of
"The Wealth of Nations;" BLACK, afterwards celebrated for his
chemical discoveries, and more especially for his theory of latent
heat; and ROBERT SIMSON, rendered illustrious by his works on
ancient geometry. In releasing Watt from the persecution of the
Glasgow corporation, these distinguished persons first imagined that
they were conferring a benefit merely on an industrious and clever
artisan, whose engaging manners won their regard; but a short
acquaintance with him was sufficient to convince them how superior
his mind was to his position, and they conceived towards him the
most lively friendship. His shop became the common rendezvous, the
afternoon lounge, of all who were most distinguished for literary
and scientific attainments among the professors and students. There
they met to discuss the topics of the day in art, science, and
literature. Among these students, the name which afterwards attained
the highest distinctions, and among these distinctions, not the
least, the lasting personal friendship and esteem of Watt himself,
was ROBISON, [Pg082] the author of a well known work on Mechanics,
and one of the contributors to the _Encyclopœdia Britannica_.
The following extract from an unpublished manuscript by Robison
himself will show at once the estimation in which Watt was held,
and will illustrate one of the most interesting traits of his
personal character:—
"I had always, from my earliest youth, a great relish for the
natural sciences, and particularly for mathematical and mechanical
philosophy, when I was introduced by Drs. Simson, Dick, and Moor,
gentlemen eminent for their mathematical abilities, to Mr. Watt. I
saw a workman, and expected no more; but was surprised to find a
philosopher as young as myself, and always ready to instruct me. I
had the vanity to think myself a pretty good proficient in my
favourite study, and was rather mortified at finding Mr. Watt so
much my superior. . . . Whenever any puzzle came in the way of any
of the young students, we went to Mr. Watt. He needed only to be
prompted, for every thing became to him the beginning of a new and
serious study, and we knew that he would not quit it till he had
either discovered its insignificancy, or had made something of it.
He learnt the German language in order to peruse Leupold's
'Theatrum Machinarum;' so did I, to know what he was about.
Similar reasons made us both learn the Italian language. * * *
When to his superiority of knowledge is added the _naïve_
simplicity and candour of Mr. Watt's character, it is no wonder
that the attachment of his acquaintances was strong. I have seen
something of the world, and am obliged to say I never saw such
another instance of general and cordial attachment to a person
whom all acknowledged to be their superior. But that superiority
was concealed under the most amiable candour, and a liberal
allowance of merit to every man. Mr. Watt was the first to ascribe
to the ingenuity of a friend things which were nothing but his own
surmises, followed out and embodied by another. I am the more
entitled to say this, as I have often experienced it in my own
case."
Watt never permitted the inquiries which arose out of these
reunions to interfere with the discharge of the duties of his
workshop. There he passed the day, devoting the [Pg083] night to
study. Every inquiry appeared to him to be attractive in
proportion to its difficulty, and to have charms in proportion as
it was removed from the common routine of his business. As an
example of this may be mentioned the fact, that, being himself so
insensible to the charms of music that he could not distinguish
one note from another, he was actually induced to undertake the
construction of an organ, in which he was nevertheless completely
successful. The instrument he constructed, as might have been
expected, contained many improvements in its mechanism; but what
is much more remarkable, its tone and its musical qualities
commanded the admiration of all the professional musicians who
heard it. In the construction of this instrument Watt showed that
vigorous spirit of investigation which characterised all the
subsequent labours of his life. He made out the scale of
temperament by the aid of the phenomena of beats, of which he
could only obtain a knowledge by a profound but obscure work
published by Dr. Robert Smith of Cambridge.
The earliest occasion on which the attention of Watt is said to
have been called to the agency of steam, was in the year 1759,
when his friend Robison entertained some speculations for applying
that agent as a means of propelling wheel carriages; and he
consulted Watt on the subject. No record, however, has been
preserved of any experiments which were tried on this occasion;
nor does it appear that the inquiry was carried farther than a
verbal discussion, such as habitually took place on other subjects
of science between Watt and his friends.
(46.) In 1762, Watt tried some experiments on the force of steam
at a high pressure, confined in a close digester; and he then
constructed a small model to show how motion could be obtained
from that power. The practicability of what has since been called
the _High Pressure Engine_, was demonstrated by him on this
occasion; but he did not pursue the inquiry, on account of the
supposed danger of working with such compressed steam as was
required.
It is usual to provide, in the cabinets of experimental apparatus
for the instruction of the students of universities, [Pg084]
small working models of the most useful machines. In the
collection for the illustration of the lectures delivered to the
Natural Philosophy class in the University of Glasgow was a
working model of Newcomen's atmospheric engine, applied to a pump
for raising water; which, however, had never been found to work
satisfactorily. The Professor of Experimental Philosophy of that
day, Dr. John Anderson (the founder of the celebrated Andersonian
Institution), sent this model in 1763 to Watt's workshop, to be
repaired. Its defects soon disappeared, and it was made to work to
the satisfaction of the professor and students.
This simple discharge of his duty, however, did not satisfy the
artisan; and his wonted activity of mind rendered this model a
subject of profound meditation, and led him into a course of
practical inquiry respecting it, which formed the commencement of a
most brilliant career of mechanical discovery. The improvement—we
might almost say the creation—of the steam engine, by this great
man, must not therefore be regarded, as so often happens with
mechanical discoveries, as the result of fortuitous observation, or
even of a felicitous momentary inspiration. Watt, on the other hand,
conducted his investigation by a course of deep thought, and of
experiments marked by the last refinement of delicacy and address.
If he had received a more extended and liberal education, one would
have thought that he had adopted for his guide the celebrated maxim
of Bacon:—
"To write, speak, meditate, or act, when we are not provided with
_facts_ to direct our thoughts, is to navigate a coast full of
dangers without a pilot, and to launch into the immensity of the
ocean without either rudder or compass."
The model which he had repaired, had a cylinder of only two inches
diameter, and six inches stroke. After he had put it in complete
order, he found, that although the boiler was much larger in
proportion to the cylinder than those of real engines, yet, that
it was incapable of supplying the cylinder with steam in
sufficient quantity to keep it at work. To enable it to continue
to move, he found it necessary to lessen the quantity of water
raised by its pump, so as to [Pg085] reduce the load on its
piston very much below the proper standard according to the common
rules for large engines.
He ascribed the great inferiority in the performance of the model,
compared with the performance of the large engines, to the small
size of the cylinder, and to its material. The cylinder of the
model was brass, while those of large engines were of cast iron;
and brass being a better conductor of heat than iron, he concluded
that more heat in proportion was lost from this cause in the
model, than in the larger engines. He observed that the small
cylinder was so heated when the steam was admitted into it, that
it could not be touched by the hand; but, nevertheless, that this
heat contributed nothing to its performance, inasmuch as before
the piston descended, the cylinder required to be cooled.
(47.) His first attempt to improve the engine, was by using a
wooden cylinder instead of an iron one. He accordingly made a
model with a cylinder of wood, soaked in linseed oil, and baked to
dryness. With this he made numerous experiments, and found that it
required a less quantity of water to be thrown into the cylinder
to condense the steam, and that it was worked with a less supply
of steam from the boiler than was necessary with the metallic
cylinder.
Still he found that the force with which the piston descended was
considerably less than that which the atmospheric pressure ought
to supply, supposing a tolerably perfect vacuum to be produced
under the piston. This led him to suspect that the water injected
into the cylinder was not perfectly effectual in condensing the
steam. The experiments which he had previously made on the
increased temperature at which water boils under pressures greater
than that of the atmosphere, led him by analogy to the conclusion
that it would boil at lower temperatures if it were submitted to a
pressure less than the atmosphere, and he was aware that Dr.
Cullen and others had then recently discovered that in vacuo,
water would boil at so low a temperature as 100°. These notions
suggested the probability that the water injected into the
cylinder being heated by the condensed steam, might produce vapour
of a low temperature [Pg086] and reduced pressure under the
piston, which would account for the deficiency he observed in the
power of the engine.
No means occurred to him by which he could ascertain, by direct
experiment, the temperatures at which water would boil under
pressures less than that of the atmosphere. He sought, however, to
determine it by the following method. Having ascertained, by
repeating and multiplying the experiments which he had tried in
1762, on high-pressure steam, he obtained a table of the
temperatures at which water boils at various pressures greater
than that of the atmosphere. These results he laid down in a
series forming a curve, of which the abscissa represented the
temperatures, and the ordinates the pressures. He then continued
this curve, backwards as it were, and obtained, by analogy, an
approximation to the boiling temperatures, corresponding to
pressures less than that of the atmosphere. In other words, having
obtained by his experiments a notion, however imperfect, of the
law or rule observed by the temperatures at which water boils at
different pressures _greater_ than that of the atmosphere, he
calculated by the same law or rule what the pressures would be at
different pressures _less_ than that of the atmosphere.
Applying these results to the interior of the cylinder of the
atmospheric engine, he obtained an approximation to the pressure
of the vapour which would be produced from the warm water formed
by the cold water injected into the cylinder, and the steam
condensed by it; and he accordingly found that vapour, having a
pressure seriously injurious to the power of the engine would be
produced in the cylinder, unless considerably more water of
injection was thrown in than was customary.
It was apparent that the actual quantity of steam usefully
employed in the cylinder at each stroke, was only the quantity
which filled the cylinder; and therefore, in order to ascertain
the quantity of steam lost by the imperfections of the machine, it
was necessary to compare the actual quantity of steam transmitted
by the boiler to the cylinder at each stroke, with the quantity
which would just fill the cylinder. The difference would of course
be wasted. But to determine [Pg087] the actual quantity of steam
supplied by the boiler to the cylinder, there was no other means
than by observing the quantity of water evaporated in the boiler.
That being observed, it was necessary to know the quantity of
steam which that water formed; and it was therefore necessary to
determine the quantity or volume of steam which a given volume of
water produced.
(48.) On considering more attentively the operation of the
machine, the following circumstances gradually unfolded themselves
to him.
Let us suppose the piston at the top of the cylinder, and the
space in the cylinder below it, filled with steam so as to balance
the pressure of the atmosphere above the piston. Under such
circumstances the steam, as will presently be explained, must have
the temperature of boiling water. But that the steam should have,
and should maintain, this temperature, it was evidently necessary
that the inner surface of the cylinder in contact with it should
have the same temperature: for if it had a lower temperature, it
would take heat from the steam, and reduce the temperature of the
latter. Now the cylinder being a mass of metal, has a quality in
virtue of which heat passes freely through its dimensions, so that
its inner surface could not be maintained at a temperature more
elevated than that of its dimensions extending from the inner
surface to the outer surface. Therefore, to maintain the steam
contained in the cylinder at the proper temperature, it was
essential that the whole of the solid metal composing the cylinder
should be itself at that temperature.
Things being in this state, it was required that a vacuum should
be produced under the piston to give effect to the atmospheric
pressure above it, by relieving it from the pressure below. This,
indeed, would appear to have been attained by introducing as much
cold water within the cylinder as would be sufficient to reconvert
the steam contained in it into water; but Watt found, in his
experiments on the atmospheric model, that the piston would not
descend with the proper force, unless a vastly greater quantity of
water were introduced into the cylinder than the quantity which he
had ascertained to be [Pg088] necessary for the reconversion of
the steam into water. The cause of this he perceived and fully
explained.