F. (François) Arago.

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lings between the two rivers of the Forth and the Clyde,
forerunners of the gigantic works of which that part of
Scotland was to be the theatre, we find Watt occupied
with similar operations along a rival line crossing the
Lomond passage. Later, he draws the plan of a canal
that was to bring coals from Monkland to Glasgow, and
superintends the execution of it. Several projects of a
similar nature, and, among others, that of a navigable
canal across the Isthmus of Crinan, which Mr. Rennie
afterwards finished ; some deep studies on certain im-
provements in the ports of Ayr, Glasgow, and Greenock ;
the construction of the Hamilton and Rutherglen bridges ;
surveys of the ground througli which the celebrated Cale-
donian Canal was to pass, occupied our associate up to
the end of 1773. Without wishing at all to diminish the
merit of these enterprises, I may be permitted to say that
their interest and importance was chiefly local, and to


assert that neither their conception, direction, nor execu-
tion required a man called James Watt.

If I were to forget my duties as the mouthpiece of the
Academy, and endeavour more to make you smile than
try to relate useful truths, I should find matter here for
a striking contrast. I might cite this or that author
who, at our weekly meetings, labours loudly to commu-
nicate some little remarks, some trifling reminiscence,
some little note, conceived and got up the previous even-
ing ; I might represent him cursing his destiny, because
some clause in the rules, or the order of insertion of
some author, an earlier riser than himself, occasions his
lecture to be deferred for a week, allowing him the
guarantee, during the whole of that cruel week, of his
sealed paquet being deposited in our archives. On the
other hand, we should see the inventor of a machine
destined to form an epoch in the annals of the world,
undergo without a murmur the stupid contempt of
capitalists, and during eight years bend his superior
genius down to surveys, plans, and minute levellings ; to
troublesome items of clearing or filling in, and to toises
of masonry. Let us confine ourselves to supposing that
Watt's philosophy led to serenity of character, modera-
tion in desires, to true modesty. But so much indiffer-
ence, however noble the cause may have been, should
have its just limit. It is not without ample motive that
society severely reprobates those of its members who
withdraw from circulation the heaps of gold contained in
their iron chests. Are we less culpable if we deprive
our country, our fellow-citizens, our century, of the
treasures, a thousand times more precious, resulting
from the exercise of mind ; if we keep to ourselves
immortal inventions, sources of the most noble, of the


purest enjoyments of intellect ; if we do not reward the
creators of mechanical combinations, which would mul-
tiply the products of industry to infinity ; who would
weaken, to the benefit of civilization and humanity, the
effect of the difference of position ; who would some day
allow the rudest manufactories to be examined without
finding, in any part of them, the distressing spectacle of
fathers of families and children of both sexes assimilated
to brutes, advancing precipitately to their tombs ?

In the early part of 1774, after contending with Watt's
indifference, his friends put him into communication with
Mr. Boulton, of Soho, near Birmingham ; an enterpris-
ing active man, gifted with various talents.* The two

* In the notes which accompanied the last edition of Professor
Eobison's Essay on the Steam-engine, Watt expressed himself in the
following terms relative to Mr. Boulton : " The friendship that he
bore me ended only with his life. The friendship that I bore him
leads me to feel it my duty to avail myself of this opportunity, the
last, probably, that will be offered me, to say how much I was in-
debted to him. It is to the earnest encouragement held out to me by
Mr. Boulton, to his taste for scientific discoveries, and to the sagacity
with which he applied them to the progress of the arts ; it is also to the
intimate knowledge he possessed of manufacturing and commercial
affairs, that I attribute, in great measure, the success with which my
efforts have been crowned."

Mr. Boulton had already had a manufoctory for several years at
Soho, when the partnership began which has rendered his name so
inseparable from that of Watt. This establishment, the first that
had been formed on so large a scale in England, is still quoted for its
elegant architecture. Boulton used to make there all sorts of work in
steel, in plated articles, in silver, in or moulu ; even to astronomical
clocks, and paintings on glass. During the last twenty years of his
life, Boulton occupied himself with improving the coining of money.
By the combination of some operations invented in France, with new
presses and an ingenious application of the steam-engine, he con-
trived to unite an exceeding rapidity of performance with perfection
of work. It was Boulton who executed for the English Government
the recoining of the whole copper currency in the United Kingdom.


friends applied to Parliament for a prolongation of privi-
lege ; since Watt's Patent, dated 1769, had only a few
more years to run. The bill gave rise to the most
animated discussion. The celebrated mechanic wrote as
follows to his aged father : " This business could not be
carried on without great expense and anxiety. With-
out the aid of some warm-hearted friends, we should not
have succeeded, for several of the most powerful people
in the House of Commons were opposed to us." It
seemed to me interesting to search out to what class of
society these Parliamentary persons belonged, to whom
Watt alluded, and Avho refused to the man of genius a
small portion of the riches that he was about to create.
Judge of my surprise, when I found the celebrated
Burke at their head ! Is it possible then that men may
devote themselves to deep studies, possess knowledge
and probity, exercise to an eminent degree oratorical
powers that move the feelings, and influence political
assemblies, yet sometimes be deficient in plain common
sense ? Now, however, owing to the wise and important
modifications introduced by Lord Brougham in the laws
relative to patents, inventors will no longer have to
undergo the annoyances with which Watt was teased.

As soon as Parliament had granted a prolongation of
twenty-five years to Watt's patent, he and Boulton
together began the establishments at Soho, which have

The economy and correctness of this great work rendered counter-
feiting almost impossible. The numerous executions with which the
towns of London and Birmingham had been annually afflicted till
then, entirely ceased. It was on this occasion that Dr. Darwin ex-
claimed in his Botanical Garden, " If at Rome a civic crown was
awarded to those who had saved the life of a single fellow-citizen, did
not Boulton deserve to be covered with crowns of oak by usV "
Mr. Boulton died in 1809, at the age of eighty-one years.


become the most useful school in practical mechanics for
all England. The construction of draining pumps of
very large dimensions was soon undertaken there, and
repeated experiments showed that, with equal effect,
they saved three quarters of the fuel that was consumed
by Newcomen's previous engines. From that moment
the new pumps were spread through all the mining
counties, especially in Cornwall. Boulton and Watt
received as a duty the value of one third of the coal
saved by each of their engines. We may form an
opinion of the commercial importance of the invention
from an authentic fact ; in the Chace-water Mine alone,
where three pumps were at work, the pi'oprietors found
it to their advantage to buy up the inventor's rights for
the annual sum of 60,000 francs (£2,400). Thus in
one establishment alone, the substitution of the condenser
for internal injection, had occasioned an annual saving
in fuel of upwards of 180,000 francs (£7,000).*

Men are easily reconciled to paying the rent of a
house, or the price of a farm. But this good-will disap-
pears when an idea is the subject treated of, whatever
advantage, whatever profit, it may be the means of pro-
curing. Ideas ! are they not conceived without ti'ouble
or labour ? Who can prove but that with time the same
might not have occurred to everybody ? In this way
days, months, and years of priority would give no force
to a patent !

Such opinions, which I need not here criticize, had

obtained a footing from mere routine, as decided. Men

* Here it must be borne in mind that a principal method of insur-
ing a return for their outlay, was their manufacturing steam-engines
on the most extensive scale, with a degree of accuracy never before
applied in the production of large machinery; and this was so fully
accomplished, that all other engines were superseded. — Tramlator.


of genius, the manufacturers of ideas, it seemed, were
to remain strangers to material enjoyments ; it Avas
natural that their history should continue to resemble a
legend of martyrs !

Whatever may be thought of these reflections, it is
certain that the Cornwall miners paid the dues that were
granted to the Soho engineers with increased repugnance
from year to year. They availed themselves of the very
earliest difficulties raised by plagiarists, to claim release
from all obligation. The discussion was serious ; it
might compromise the social position of our associate ;
he therefore bestowed his entire attention to it, and be-
came a lawyer. The long and expensive lawsuits that
resulted therefrom, but which they finally gained, Avould
not deserve to be now exhumed ; but having recently
quoted Burke as one of the adversaries to our great
mechanic, it appears only a just compensation here to
mention that the Roys, Mylnes, Herschels, Delucs,
Eamsdens, Robisons, Murdocks, Rennies, Cummings,
Mores, Southerns, eagerly presented themselves before
the magistrates, to maintain the rights of persecuted
genius. It may be also advisable to add, as a curious
trait in the history of the human mind, that the lawyers
(I shall here prudently remark that we treat only of the
lawyers of a neighbouring country), to whom malignity
imputes a superabundant luxury in words, reproached
Watt, against whom they had leagued in great numbers,
for having invented nothing but ideas. This, I may
remark in passing, brought upon them before the tribu-
nal, the following apostrophe from Mi-. Rous : * " Go,

* Mr. Rous, who acted as counsel for the patentees, published his
speech in the form of a pamphlet. In the text we have reproduced
the English from a version of M. Arago's French, an unsatisfactory


gentlemen, go and rub yourselves against those untangible
combinations, as you are j^leased to call Watt's engines —
against those pretended abstract ideas ; they will crush
you like gnats, they will hurl you up in the air out of
sight ! "

The persecutions which a warm-hearted man meets
with, in the quarters where strict justice would lead him
to expect unanimous testimonies of gratitude, seldom fail
to discourage, and to sour his disposition. Nor did Watt's
good humour remain proof against such trials. Seven
long years of lawsuits had excited in him such a senti-
ment of indignation, that it occasionally showed itself in
severe expressions ; thus he wrote to one of his friends :
— " What I most detest in this world are plagiarists.
The plagiarists ! They have already cruelly assailed me ;
and if I had not an excellent memory, their impudent as-
sertions would have ended by persuading me that I have
made no improvement in steam-engines. The bad pas-
sions of those men to whom I have been most useful —
would you believe it ? have gone so far as to lead them
to maintain that those improvements, instead of deserving
this denomination, have been highly prejudicial to public

practice arising from necessity; for, in his full acquaintance ■with our
writings, he is exuberant in quotations without always giving chap-
ter and verse ; and, moreover, many of the cited passages are from
letters and other manuscript documents. In the instance before us,
the keen satire of Rous was in asking the opposite party whether it
could be seriously contended that Watt's invention, which, during the
space of nearlj' thirty years, had been admired in all Europe as the
greatest jiractical advance ever made in the arts, was a mere ahstract
discovery in science ; and, he observed, that if those who thus pleaded
were to approach the untancjible substance, as they were pleased to call
it, with the same ignorance of its nature that they thus affected, they
would be crushed before it like flies, leaving no trace of their exist-
ence. — Translator.


Watt, though greatly irritated, was not discouraged.
His engines were not, in the first place, like Newco-
men's, mere pumps, mere di-aining pumps. In a few
years he transformed them into universal motive pow-
ers, and of indefinite force. His first step in this line
was the invention of a double-acting engine (a double

To conceive the principle of it, let my report of the
modified engine of which I have already treated (page
391,) be consulted. The cylinder is closed ; the ex-
ternal air has no access to it ; it is steam pressure, and
not atmospheric, that makes the piston descend ; the
ascending movement is due to a simple counterpoise, be-
cause at the moment when this takes place, the steam,
being enabled to circulate freely from the higher to the
lower portions of the cylinder, presses equally on the
piston in both directions. Every one will hence see, that
the modified engine, or Newcomen's, has power only
during the descending oscillation of the piston.

A very simple change remedied this serious defect, and
produced the double-acting engine.

In the engine known under this name, as well as in
the one which we denominated the modified engine, the
steam from the boiler, when the mechanic wishes it, goes
freely above the piston and presses it down without
meeting any obstacle; because at that same moment,
the lower area of the cylinder is in communication with
the condenser. This movement once achieved, and a
certain cock having been opened, the steam from the
caldron can enter only below the piston, and elevates it ;
the steam above it, which had produced the descending
movement, then goes to regain its fluid state in the con-
denser, with which it has become, in its turn, in free


communication. The contrary arrangement of the cocks
replaces all things in their primitive state, as soon as the
piston has regained its maximum height. Thus similar
effects are reproduced indetinitely.

The motive power is here, as explained above, exclu-
sively steam ; and the engine, except by the inequality
arising from the weight of the piston, has the same power
whether the piston be ascending or descending. This is
the reason why, from the moment of its appearance it w^as
justly called a donhle-acting engine.

To render this new motive power of easy and conve-
nient application, Watt had to overcome other difficulties :
it was requisite to find the means of establishing a rigid
communication between the inflexible rod of the piston
oscillating in a straight line and a beam that oscillated
circularly. The solution which he gave of this important
problem is perhaps his most ingenious invention.

Among the constituent parts of a steam-engine, you
have, no doubt, remarked a certain articulated parallelo-
gram. With each double oscillation it develops and con-
tracts itself, with the smoothness of motion, — I had
almost said with the grace, — that charms us in the ges-
tures of a consummate actor. Follow attentively with
your eye its various transformations, and you will find it
subject to the most curious geometrical conditions ; that
three of the summits of the parallelogram's angles describe
arcs of circles in space, whilst the fourth, the summit of
the angle that raises and lowers the piston-rod, moves
very nearly in a straight line. The immense utility of
the result strikes mechanics less than the simplicity of
means by which Watt obtained it.*

* We here give Watt's words in relating the experiment of this artic-
ulated parallelogram {Ms beautiful arranijement is called parallel mo-


Power is not the only element of success in industrial
worivs. Regularity of action is not less important ; but
what regularity could be expected from a motive power
engendered by fire fed by shovels full, and the coal itself
of various qualities ; and this under the direction of a
workman, sometimes not very intelligent, almost always
inattentive ? The motive steam will be more abundant,
it will flow more rapidly into the cylinder, it will make
the piston work faster in proportion as the fire is
more intense. Great inequalities of movement then ap-
pear to be inevitable. Watt's genius had to provide
against this serious defect. The throttle-valves by which
the steam issues from the boiler to enter the cylinder are
not constantly open. When the working of the engine
accelerates, these valves partly close ; a certain vol-
ume of steam must therefore occupy a longer time in
passing through them, and the acceleration ceases. The
aperture of the valves, on the conti-ary, dilates when the
motion slackens. The pieces requisite for the perform-
ance of these various changes connect the valves with
the axes which the engine sets to woi*k, by the introduc-

tion — Translator): "I was myself surprised at the regularity of its
action. When I saw it work for the first time, I felt truly all the
pleasure of novelty, as if I was examining the invention of another

SmeatOD, who was a great admirer of Watt, did not believe, how-
ever, that it could in practice become a general and economical
means of impressing directly rotatory motion to axes. He maintained
that steam-engines would always be more serviceable in pumping
water direct. This fluid having reached a suitable height, was then to
be thrown into the trough, or on to the pallets of common hydraulic
wheels. In this respect the prophecies of Smeaton were not realized.
Yet, in 1834, on visiting the establishment of Mr. Boulton at Soho, I
saw an old steam-engine still employed to raise water from a large
pool, and pour it into the troughs of a great hydraulic wheel, when
the season being ver}- dry the water-power was insufficient.


tion of an apparatus, the principle of which Watt dis-
covered in the reguhxtor of the sails of some flour-mills :
this he named the governor; which is now called the
centrifugal regulator. Its efficacy is such, that a few
years ago in the cotton-spinning manufactory of a re-
nowned mechanic, Mr. Lee, there was a clock set in
motion by the engine of the establishment, and it showed
no great inferiority to a common spring clock.

Watt's regulator, and an intelligent use of the re-
volving principle, — that is the secret, the true secret, of
the astonishing perfection of the industrial products of
our epoch ; this is what now gives to the steam-engine
a rate entirely free from jerks. That is the reason why
it can, with equal success, embroider muslins and forge
anchors, -weave the most delicate webs and communicate
a rapid movement to the heavy stones of a flour-mill.
This also explains how Watt had said, fearless of being
reproached for exaggeration, that to prevent the comings
and goings of servants, he would be served, he would
have gruel brought to him, in case of illness, by tablets
connected with his steam-engine. I am aware it is sup-
posed by the generality of people, that this suavity of
motion is obtained only by a loss of power ; but it is an
error, a gross error : the saying, " nmch noise and little
work," is true not only in the moral world, but is also an
axiom in mechanics.

A few words more and we shall reach the end of our
technical details.

Within these few years, great advantage has been
found in not allowing a free access of steam from the
boiler into the cylinder, during the ivhole time of each
oscillation of the engine.* This communication is inter-

* This constituted Watt's celebrated expansion engine, so named


riipted, for example, when the piston has reached one
third of its course. The two remaining thirds of the
cyHnder's length are then traversed by virtue of the ac-
quired velocity, and especially by the detention of the
steam. Watt had already indicated such an arrange-
ment.* Some very good judges esteem the economical
importance of the steam-detent as equal to that of the
condenser. It seems certain that since its adoption, the
Cornwall engines give unhoped-for results ; that with one
bushel of coals they equal the labour of twenty men
during ten hours. Let us keep in mind, that in the coal
districts a bushel of coals only costs ninepence, and it
will be demonstrated that over the greater part of Eng-
land, Watt reduced the price of a man's day's work, a
day of ten hours' labour, to less than a sou (one half-
penny,) of our money.f

because the small portion of steam already admitterl, then expanded
till the piston had reached the end of tiie cylinder. — Translator.

* The principle of the steam detention had been neatly expressed
in a letter from Watt to Dr. Small dated 1769, it was put in practice
in 1776, at Soho, and also in 1778 at the Shadwell leater works, from
economical considerations. The invention, and the advantages ex-
pected from it, are fully described in the patent of 1782.

t At a moment when so many people are interested in direct rota-
tion engines, I should be unpardonably neglectful if I did not say that
Watt had both thought of them, as proved in his patents, and had
made some. Watt abandoned those engines, not because they would
not work, but because, in an economical point of view, they appeared
to him decidedly inferior to the double-acting engines, and to those
with rectilinear oscillations.

There are few inventions, large or small, amongst those of which
the steam-engine oflers us such an admirable assemblage, that have
not been developed from some of Watt's early ideas. Follow up his
labours, and besides the important points which we have minutely
detailed, you will see him propose engines without condensation,
engines in which the steam, after having acted, is allowed to escape
into the open air, for those localities where it would be difficult to
procure an abundance of cold water.


Numerical valuations make us appreciate so well the
importance of his inventions, that I cannot resist the de-
sire to present two more improvements. I borrow them
from one of the most celebrated correspondents of the
Academy, from Mr. John Herschel.

The ascent of Mont Blanc, starting from the valley of
Chamouni, is justly considered as the hardest work that
a man can accomplish in two days. Thus, the maximum
mechanical work of which we are capable, in twice twenty-
four hours, is measured by transporting the weight of our
body to the elevation of Mont Blanc. This work, or its
equivalent, would be accomplished by a steam-engine in
the course of burning one kilogram of coal. Watt has,
therefore, ascertained that the daily power of a man does
not exceed what is contained in half a kilogram of coal
(1 lb. Avs.).

Herodotus records that the construction of the great
pyramid of Egypt employed one hundred thousand men
during twenty years. The pyramid consists of calcareous

The detent intended to be used in engines having several cylinders,
-will also figure among the projects of the Soho engineer. He suggests
the idea of perfectly water-tight pistons, thougli consisting entirely of
pieces of metal. It was Watt also who first had recourse to mercurial
gauges to appreciate the elasticity of the steam, both in the boiler ^nd
in the condenser; who imagined a simple and permanent gauge, by
the aid of which, and at a glance, tlie height of the water in the boiler
can be known; and who, to prevent this levol from ever varying to an
inconvenient extent, connected the movements of the feeding-pump
with those of a float, which, when required, was placed in an opening
of the lid of the engine's principal cylinder, forming a little indicator,
so combined as to show exactly the law of the steam's consumption

Online LibraryF. (François) AragoBiographies of distinguished scientific men (Volume 2) → online text (page 31 of 38)