F. (François) Arago.

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hissed the partisans of the despot Cardinal and applauded
the poet. This reparation is denied to the geometer, the
astronomer, or the physicist, who cultivate the highest
parts of science. Those who can competently appreciate
them throughout the whole extent of Europe never rise
above the number of eight or ten. Imagine these unjust,
indifferent, or even jealous, (for I suppose that may some-
times be the case,) and the public, reduced to believe on
hearsay, would be ignorant that D'Alembert had con-
nected the great phenomenon of precession of equinoxes
with the principle of universal gravitation ; that Lagrange
had arrived at the discovery of the physical cause of the
libration of the moon ; that since the researches of La-


place, the acceleration of the motion of that luminary is
found to be connected with a i^articular change in the
form of the earth's orbit, &c. &c. The journals of science,
when thej are edited by men of recognized merit, thus
acquire, on certain subjects, an influence which some-
times becomes fatal. It is thus I conceive that we may
describe the influence which the Edinburgh Review has
sometimes exercised.

Among the contributors to that celebrated journal at
its commencement, a young writer was eminently distin-
guished, in whom the discoveries of Newton had inspired
an ardent admiration. This sentiment so natural, so
legitimate, unfortunately led him to misconceive the plau-
sible, ingenious, and fertile character of the doctrine of
interferences. The author of this- theory had not, per-
haps, always taken care to clothe his decisions, his state-
ments, his critiques, with those more polished forms of
expression the claims of which ought never to be neg-
lected, and which moreover, became a matter of imper-
ative duty when the question referred to the immortal
author of the Natural Philosophy * [the Principia ?]

* It seems impossible to malce this sentence intelligible unless we
suppose the "immortal author" spoken of to be Newton, and by con-
sequence that the title Nalural Philosophy was a slip of the writer's
pen, for Principia. Yet the supposition that the hostility of the Eclin-
burc/h Review was at all called forth by any want of courtesy towards
Newton in the writings of Young is wholly unsupported by any thing
in Young's papers, in which he cites the views of Newton with the
greatest respect. — Translatm:

NevHon's support of the emission theory of light. — The authority of
names can never be of any avail to the truly inductive philosopher, —
his motto is emphatically "nullius in verba." But there has been
always a propensity among writers on the subject to dwell on such
authority, and to array great names on either side of any of those contro-
verted points which have divided the scientific world. Perhaps where
the question is purely one of opinion and refers simply to hypotheses,


The penalty of retaliation was applied to him with inter-
est ; the Edinhurgh Revieio attacked the man of erudi-

upheld for what they are worth as such, the weight of a name may not
be imworthy of due estimation ; great experience and high genius may
add value to a pure Jnjpothcsis though it could not to a positive conclu-
sion. In regard to theories of light this has been conspicuously exem-
plified, and during a long continuance of controversial discussion it
has been a matter of triumph to the opponents of the undulatory the-
ory that tlie authority of Newton is on their side. And even Arago
as well as some other supporters of it have spoken as if regretting that
they were thus constrained to put themselves in antagonism to New-
ton. They have pictured two rival theories, the one headed by New-
ton and supported by Laplace, Biot, Brewster and Potter, the other
upheld in opposition to them bj' Huyghens, Hooke, Euler, Young,
Fresnel, Airy and all the Cambridge school.

But a very slight inquiry into the real facts entirely dispels this
view of the case. In particular Dr. Young himself in proposing his
theory, so far from opposing the Newtonian views, expressly endeav-
ours to conciliate attention by claiming the weight of Newton's author-
ity 011 his own side : thus in his paper " On the Theory of Light and
Colours," (Phil. Trans. 1801,) he commences by highly extolling the
optical researches of Newton, and then observes, "those who are
attached, as they may be with the greatest justice, to 'every doctrine
which is stamped with the Newtonian approbation, will probably be
disposed to bestow on these considerations (i. e. his own views) so
much the more of their attention as they shall appear to coincide more
nearly with Newton's opinion." He then proceeds to examine in de-
tail a number of passages from Newton's writings in which the theoiy
of waves is distinctly upheld and even applied with some precision
to the explanation of various phenomena of light, illustrated by their
analogies to those of sound.

It is perfectly true that Newton in the actual investigation of several
phenomena of light adopts other hypotheses than those of waves; and
chiefly the idea of light (whatever may be its nature) being subject to
certain attractions and repulsions, — to certain bendings when approach-
ing near the edges of solid bodies, — to certain peculiar modifications or
changes in its nature recurring periodically at certain minute intervals
along the length of a ray, — to the idea of a ray having " sides " endued
with different properties ; in a word, a variety of conceptions, which he
introduces for the purpose of giving some kind of imaginarj' physical
representation of the inodiis operandi in each of the several curious


tion, the writer, the geometer, the experimenter, with a
vehemence, with a severity of expression almost with-

experimental cases which he had examined. In all these there is no
unity or community of principle, there is at least nothing like the spirit
of theory, no continual recurrence to one leading idea, — no perpetual
appeal to any one principle however imaginarj', but an attempt in each
isolated case to frame something like an isolated hypothesis to suit it,
and in some way to represent its phenomena though without any
attempt to connect them with the others. It maj- perhaps be said that
all these various suppositions agree in supposing light to be material,
to be something emitted from the luminous source. But on a closer
examination it seems far from certain that even this can be main-
tained. The only part of these investigations, perhaps, in which any
thing very positive of this kind is distinctly introduced, is when New-
ton investigates tlie laws of refraction, on the express supposition of
small molecules attracted by the molecules of tlie medium. But in
this instance it has been truly observed, that at the time when New-
ton wrote, no mathematical method existed by which this kind of
action could be reduced to calculation except those involving the ac-
tion of attractive force. To give, then, a mathematical theory of ordi-
nary reflexion and refraction he was necessitated to make use of this
method. When he came to investigate those more recondite phenom-
ena which he (very appropriately to their apparent nature) called
"inflexion," the idea most naturally and obviously presented was,
that some power or influence, analogous to attraction and I'epulsion,
existing in the edge of an opaque body to bend out of their course rays
passing very near it, and this might seem to imply the matei'iality of
those rays. A kind of alternating action of this sort, which he imag-
ined necessary to account for a part of the effect, would, however,
hardly be reconcilable to the idea of direct emission. It would be a
difficult matter to conceive particles darted through space with such
inconceivable velocity as must belong to those of light, and yet stop-
ping to wave about, in and out, as Newton expresses it, "like an eel,"
close to the edge of a body, by virtue of some mysterious influence
which it exercises upon them.

Again: the theory of those alternating states, conditions, or "fits"
as he termed them, at such minute intervals along the length of ray
alternately putting it in a state to be reflected, and again to be trans-
mitted by a transparent medium, seem very remote from the idea of a
simple rectilinear progress of molecules through space following one
another at immense intervals of distance though in inconceivably rapid


out example in scientific discussion. The public usually
keeps on its guard when such violent language is ad-
dressed to it, but in this instance they adopted at the first
onset the opinions of the journalist in which we cannot
fairly accuse them of inconsiderateness. The journalist,
in fact, was not one of those unfledged critics whose mis-
sion is not justified by any previous study of the subject-
Several good papers, received by tlie Eoyal Society, had
attested his mathematical knowledge, and had assigned
him a distinguished place among the physicists to whom
optical science was indebted : the profession of the bar in
London had acknowledged him one of its shining lumi-
naries ; the Whig section of the House of Commons saw

succession in time. It would be easy to extend such remarks ; but it
■will probably be seen, with sufficient evidence for our present purpose,
that neither in profession nor in fact, can Newton's name be appealed
to as at all an exclusive supporter of the material hypothesis of light;
even if in other passages he had not distinctly referred to that of un-
dulations. And of these references a large number are quoted from
different portions of his writings, by Dr. Young, in the paper above
cited. In some of these, while he admits the readiness with which the
idea of waves represents the phenomena, he yet dwells on certain ap-
parent objections which seemed to invalidate that idea.

Upon the whole it appears that the name of Newton can in no way
be legitimately claimed as a partisan of either theory. Indeed, it is
surprising that any claim of the kind could have been set up as re-
gards the emission theory after his own distinct avowal: —

" 'Tis true that from theory I argue the corporeity of light; but I do
it without any absolute positiveness, as the word 'perhaps' intimates;
and make it at most but a very plausible consequence of the doctrine,
and not a fundamental supposition, nor so much as any part of it." —
Phil. Trans, vol. x. 1675, p. 5086.

While in respect to either hypothesis it is sufficiently evident to
those acquainted with his writings that he never systemalically upheld
either the one or the other; but from time to time, as each particular
investigation seemed to require, he adopted the one or the other prin-
ciple just as it seemed to give the more ready explanation of the point
before liim. — Translator.


in him an efficient orator who in parliamentary struggles
was often the happy antagonist of Canning ; this was the
future President of the House of Peers, — the present
Lord Chancellor.* How could opposition be offered to
unjust criticisms proceeding from so high a quarter ? I
am not ignorant what firmness some minds enjoy in the
consciousness of their being in the right ; in the certainty
that sooner or later truth will triumph ; but I know also,
that we shall act wisely in not reckoning too much on
such exceptions. Listen, for example, to Galileo him-
self, repeating in a whisper after his abjuration, " E pur
si muore ! " and do not seek in these immortal words an
augury for the future, for they are but the expression of
the cruel vexation which the illustrious old man experi-
enced. Young also, in writing a few pages which he
published as an answer to the Edinburgh Review, showed
himself deeply discouraged. The vivacity, the vehe-
mence of his expressions, ill concealed the sentiment
which oppressed him. In a word, let us hasten to say
that justice, complete justice, was at length rendered to
the great physicist. After several years the whole world
recognized in him one of the brightest luminaries of the
age. It is from France (and Young took pleasure in
himself proclaiming it) that the first sign of this tardy
reparation showed itself. I will add, that at an epoch
considerably before the doctrine of interferences had
made converts either in England or on the Continent,
Young found within his own family circle one who com-
prehended it, and whose assent to it might well console
him for the neglect of the public. The distinguished
person whom I here point out to the notice of the physi-

* Lord Brougham, who held that office when this biography was


cists of Europe, will excuse me if I complete this indis-
cretion by stating the circumstances.

In the year 1816 I made a tour in England with my
scientific friend M. Gay-Lussac. Fresnel had just then
entered on his scientific career in the most brilliant man-
ner, by the publication of his memoir on Diffi-action.
This work which, in our opinion, contained a capital
experiment irreconcilable with the Newtonian theory of
light, became naturally the first subject of our discussion
with Dr. Young. We were astonished at the numerous
qualifications which he put upon our praises of it, until at
length he stated to us that the very experiment which we
so much commended had been published, so long since as
1807, in his treatise on Natural Philosophy. This asser-
tion did not seem to us well founded. It caused a long
and minute discussion. Mrs. Young was present, with-
out appearing to take any part in the conversation ; but
we imagined that the weak fear of being designated by
the ridiculous sobriquet of bas-bleu rendered the ladies
of England very reserved in the presence of foreigners ;
and our want of discernment did not strike us till the
moment when Mrs. Young quickly quitted her place ; we
then began to attempt excuses to her husband, until we
saw her reenter the room carrying under her arm a large
quarto volume. This was the first volume of the Natural
Philosophy. She placed it on the table, and without say-
ino- a word opened it at page 787, and pointed with her
finger to a diagram in which the curvilinear route of the
diffracted bands, on which the discussion turned, was the-
oretically established.

I trust I shall be pardoned these little details. Too
numerous examples may almost have habituated the pub-
lic to consider destitution, injustice, persecution, and


miseiy as the natural wages of those who devote their
vigils to the development of the human mind ! Let us
not then forget to point out the exceptions whenever they
present themselves. If we wish that youth should give
itself up with ardour to intellectual labours, let us show
them that the glory attached to great discoveries allies
itself, sometimes at least, with some degree of tranquillity
and happiness. Let us even withdraw, if it be possible,
from the history of science so many pages which tarnish
its glory. Let us try to persuade ourselves that in the
dungeons of the Inquisitors, a friendly voice had caused
Galileo to hear some of the delightful expressions which
posterity has kept sacred for his memory ; that behind
the thick walls of the Bastille, Freret might yet have
learned from the world of science, the glorious rank
which it had reserved for him among the men of erudi-
tion whom France honours ; that before going to die in
an hospital, Borelli had found sometimes in the city of
Rome a shelter against the inclemency of the atmosphere,
and a little straw on which to lay his head ; and lastly,
that the great Kepler had not experienced the sufferings
of hunger.



The Journals having done me the honour to mention some-
times the numerous testimonies of good will and friendship
which Lord Brougham had shown me in 1834, as well in Scot-
land as in Paris, a word or two of explanation here seem indis-
pensable. The eloge of Dr. Young was read at a public sitting
of the Academy of Sciences, Nov. 26, 1832. At this period
I had never had any personal acquaintance with the writer in
the Edinburgh Review, and thus all charge of ingratitude must
fall to the ground. But could you not, some might perhaps
say, have suppressed entirely, when your paper was going to
the press, all that related to so unfortunate a controversy ? I
could have done so, and in fact the idea had occurred to me ;
but I soon renounced it. I know too well the elevated feel-
ings of my illustrious friend to fear that he will take offence at
my frankness in regard to a question on which I have a pro-
found conviction that the great extent of his geni!us has not
preserved him from error. The homage which I render to the
noble character of Lord Brougham in now publishing this pas-
sa>Te of the eloge of Young without any modification, is, in my
mind, sufficiently significant to render it needless to add a word



Gentlemen, — After having waded through a long
list of battles, assassinations, plagues, famines, catastro-
phes of all sorts presented by the annals of I know not
what country, a philosopher exclaimed, " Happy the
nation whose history is tedious ! " Why ought we to
add, in a literary point of view at least, " Unhappy the
man on whom the duty falls to relate the history of a
happy people ! "

If the philosopher's exclamation loses none of its ap-
positeness when applied to mere individuals, its counter-
part characterizes with equal truth the position of some

Such were the reflections that occurred to me, whilst
I was studying the life of Jam.es Watt, and collecting
obliging communications from the relations, friends, and
companions of the illustrious mechanic. His life, quite
patriarchal, devoted to work, to study, and to meditation,
will not afford us any of those striking events the recital of
which, sprinkled vv'ith judgment among scientific details,
relieves their weight. Still I will relate it, if but to


show in what a humble position tliose projects were
perfected, that were destined to raise the British nation
to an unheard-of degree of power. I will especially en-
deavour to characterize, with extreme precision, the
fruitful inventions which will for ever connect the name
of Watt with the steam-engine. I foresee all the dan-
gers of this line of conduct ; I am aware that it may be
said on going out of this room : We expected an histor-
ical eulogy, but we have only received a dry and arid
lesson. Besides this, the reproach would not have
weighed on me, if the lesson had been well understood.
I will, therefore, exert every effort not to tire your
patience ; I will keep in mind that clearness is politeness
in public speakers.


James Watt, one of the eight Foreign Associates of
the Academy of Sciences, was born at Greenock, in
Scotland, the 19tli of Januaiy, 1736. Our neighbours
on the other side of the Channel, have the good sense
to think that the genealogy of a respectable and indus-
trious family, is quite as worthy of being preserved as
the parchments of certain titled families that have be-
come celebrated only by the enormity of their crimes
and their vices. Thus I can say with certainty that the
great grandfather of James Watt was an agriculturist,
settled in the county of Aberdeen ; that he was killed
in one of Montrose's battles ; that the conquering side,
as was customary, (I was going to add, as is still custom-
ary in civil discords,) did not think death itself a suffi-
cient expiation for tlie opinions in support of which the


poor farmer had fought ; that it punished the act in the
person of the son, by confiscating his property ; that the
unfortunate child, Thomas Watt, was received by some
distant relations ; that in the entire insulation to which
his difficult position condemned him, he assiduously
devoted himself to deep studies ; that in more tranquil
times, he settled at Greenock, where he taught mathe-
matics and the elements of navigation ; that he resided
at Crawford's Dyke, of which borough he was magis-
trate ; and that finally he died in 1734, at the age of

Thomas Watt had two sons. The eldest, John, fol-
lowed his father's profession at Glasgow. He died at
the age of fifty (1737), leaving a chart of the Clyde,*
which was published under the care of his brother James.
This James, who was the father of the celebrated engi-
neer, and for a long time treasurer of the municipal
council of Greenock, as well as magistrate of the town,
became remarkable in the performance of his duties by
his ardent zeal, and an enlightened spirit of amelioration.
He combined, (do not be alarmed ; these three syllables,
that have become a subject of general anathema in
France, will not injure the memory of James Watt,) he
combined three species of occupation ; he was at once a
seller of all sorts of nautical instruments f and stores, a

* This map is reengi'aved in the Memorials of Watt, with an adver-
tisement which ascribes its publication to James Watt, at Glasgow
College; a MS. note on one copy, said to be in the handwriting of the
Great Engineer, states that it was published by John Watt in 1760. —

t It may have been first owing to an examination of these instru-
ments, that j'oung Watt, in his eighteenth year, in conformitj- with
his own desire, was apprenticed to a mathematical instrument-maker
in London. — Translatoi\


builder, and a merchant ; which unfortunately, about the
close of his life, did not prevent certain comraei'cial spec-
ulations from depriving him of a portion of the creditable
fortune that he had gained before. He died at the age
of eighty-four, in 1782.

James Watt, the subject of this essay, was born with
a very delicate constitution. His mother, whose maiden
name was Muirhead, gave him his first instruction in
reading. He learned writing and ciphering from his
father. He also attended the Grammar School of Gree-
nock ; and thus these humble Scotch seminaries are
entitled, with just pride, to enroll the name of this cele-
brated engineer among the pupils that they have formed ;
as the College of La Fleche boasted of Descartes, as the
University of Cambridge still cites Newton.

To be correct, I must add that frequent indispositions
prevented young "Watt from punctually attending the
public school at Greenock ; that during a great portion
of the year he was confined to his room, and there
devoted himself to study, without any out-door help.
As is frequently the case with high intellectual faculties
destined to yield great results, they began to develop
tliemselves in retirement and solitude.

Watts was too sickly for his parents to think of urging
him to assiduous occupation. They even left his amuse-
ments to his free choice. We shall see whether he
abused this freedom.

A friend of Mr. Watt's one day found little James
lying on the floor, and with a piece of chalk drawing all
sorts of intersecting lines ; whereupon he exclaimed —
" Why do you allow that child to waste his time — send
liim to the public scliool ! " Mr. Watt answered : " You
might have spared us this hasty judgment ; before con-


derailing us, examine attentively what our son is doing."
Tlie apology soon followed ; the boy, only six years old,
was seeking the solution of a geometrical problem.

Prompted by an enlightened fondness, the father had
early furnished the young scholar with a certain number
of tools, and he made use of them with great ability ; he
took to pieces and put together again all the infantine
toys that came into his hands ; he continually made new
ones. When older, he applied them to the construction
of a small electrical machine ; the bright sparks from
which became a lively subject of amusement and sur-
prise to all the playfellows of the poor invalid.

Watt, with an excellent memory, still would not per-
haps have figured among the young prodigies of com-
mon schools ; he would have refused to learn lessons
like a parrot, because he felt an internal longing care-
fully to elaborate the intellectual elements which they
presented to his mind. Nature had especially created

Online LibraryF. (François) AragoBiographies of distinguished scientific men (Volume 2) → online text (page 27 of 38)