Francois Arago - Biographies of Distinguished Scientific Men

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BIOGRAPHIES

OF

DISTINGUISHED SCIENTIFIC MEN.

BY FRANCOIS ARAGO,

MEMBER OF THE INSTITUTE.

TRANSLATED BY

ADMIRAL W.H. SMYTH, D.C.L., F.R.S., &c.

THE REV. BADEN POWELL, M.A., F.R.S., &c.

AND

ROBERT GRANT, Esq., M.A., F.R.A.S.

FIRST SERIES.

BOSTON:

TICKNOR AND FIELDS.

M DCCC LIX.

RIVERSIDE, CAMBRIDGE:

PRINTED BY H.O. HOUGHTON AND COMPANY.

TRANSLATORS' PREFACE.

The present volume of the series of English translations of M. Arago's
works consists of his own autobiography and a selection of some of his
memoirs of eminent scientific men, both continental and British.

It does not distinctly appear at what period of his life Arago composed
the autobiography, but it bears throughout the characteristic stamp of
his ardent and energetic disposition. The reader will, perhaps, hardly
suppress a smile at the indications of self-satisfaction with which
several of the incidents are brought forward, while the air of romance
which invests some of the adventures may possibly give rise to some
suspicion of occasional embellishment; on these points, however, we
leave each reader to judge for himself. In relation to the history of
science, this memoir gives some interesting particulars, which disclose
to us much of the interior spirit of the Academy of Sciences, not always
of a kind the most creditable to some of Arago's former contemporaries.

But a far higher interest will be found to belong to those eloquent
memoirs, or eloges of eminent departed men of science, who had attained
the distinction of being members of the Academy.

In these the reader will find a luminous, eminently simple, and popular
account of the discoveries of each of those distinguished individuals,
of a kind constituting in fact a brief history of the particular branch
of science to which he was devoted. And in the selection included in the
present volume, which constitutes but a portion of the entire series, we
have comprised the accounts of men of such varied pursuits as to convey
no inadequate impression of the progress of discovery throughout a
considerable range of the whole field of the physical sciences within
the last half century.

The account given by the author, of the principal discoveries made by
the illustrious subjects of his memoirs, is in general very luminous,
but at the same time presupposes a familiarity with some parts of
science which may not really be possessed by all readers. For the sake
of a considerable class, then, we have taken occasion, wherever the use
of new technical terms or other like circumstances seemed to require it,
to introduce original notes and commentaries, sometimes of considerable
extent, by the aid of which we trust the scientific principles adverted
to in the text will be rendered easily intelligible to the general
reader.

In some few instances also we have found ourselves called upon to adopt
a more critical tone; where we were disposed to dissent from the view
taken by the author on particular questions of a controversial kind, or
when he is arguing in support, or in refutation, of opposing theories on
some points of science not yet satisfactorily cleared up.

We could have wished that our duty as translators and editors had not
extended beyond such mere occasional scientific or literary criticism.
But there unfortunately seemed to be one or two points where, in
pronouncing on the claims of distinguished individuals, or criticizing
their inventions, a doubt could not but be felt as to the perfect
_fairness_ of Arago's judgment, and in which we were constrained to
express an unfavourable opinion on the manner in which the relative
pretensions of men of the highest eminence seemed to be decided,
involving what might sometimes be fairly regarded as undue prejudice,
or possibly a feeling of personal or even national jealousy. Much as we
should deprecate the excitement of any feeling of hostility of this
kind, yet we could not, in our editorial capacity, shrink from the plain
duty of endeavouring to advocate what appeared to us right and true; and
we trust that whatever opinion may be entertained as to the
_conclusions_ to which we have come on such points, we shall not have
given ground for any complaint that we have violated any due courtesy or
propriety in our _mode_ of expressing those conclusions, or the reasons
on which they are founded.

CONTENTS.

PAGE
THE HISTORY OF MY YOUTH.

An Autobiography of Francis Arago 1

BAILLY.

Introduction 91

Infancy of Bailly.--His Youth.--His Literary Essays.--His
Mathematical Studies 93

Bailly becomes the Pupil of Lacaille.--He is associated
with him in his Astronomical Labours 97

Bailly a Member of the Academy of Sciences.--His Researches
on Jupiter's Satellites 103

Bailly's Literary Works.--His Biographies of Charles V.--of
Leibnitz--of Peter Corneille--of Moliere 106

Debates relative to the Post of Perpetual Secretary of
the Academy of Sciences 110

History of Astronomy.--Letters on the Atlantis of Plato
and on the Ancient History of Asia 114

First Interview of Bailly with Franklin.--His Entrance
into the French Academy in 1783.--His Reception.--Discourse.--His
Rupture with Buffon 121

Report on Animal Magnetism 127

Election of Bailly into the Academy of Inscriptions 155

Report on the Hospitals 157

Report on the Slaughter-Houses 165

Biographies of Cook and of Gresset 167

Assembly of the Notables.--Bailly is named First Deputy
of Paris; and soon after Dean or Senior of the Deputies
of the Communes 169

Bailly becomes Mayor of Paris.--Scarcity.--Marat declares
himself inimical to the Mayor.--Events of the 6th of October 179

A Glance at the Posthumous Memoir of Bailly 193

Examination of Bailly's Administration as Mayor 195

The King's Flight.--Events on the Champ de Mars 206

Bailly quits the Mayoralty the 12th of November, 1791.--The
Eschevins.--Examination of the Reproaches that might be
addressed to the Mayor 211

Bailly's Journey from Paris to Nantes, and then from Nantes to
Melun.--His Arrest in this last Town.--He is transferred to Paris 217

Bailly is called as a Witness in the Trial of the Queen.--His own
Trial before the Revolutionary Tribunal.--His Condemnation to
Death.--His Execution.--Imaginary Details added by ill-informed
Historians to what that odious and frightful Event already
presented 225

Portrait of Bailly.--His Wife 250

HERSCHEL.

Personal History 258

Chronological Table of the Memoirs of William Herschel 266

Improvements in the Means of Observation 271

Labours in Sidereal Astronomy 285

Labours relative to the Solar System 289

Optical Labours 301

LAPLACE.

Preliminary Notice 303

APPENDIX.

(A.) Brief Notice of some other interesting Results
of the Researches of Laplace which have not
been mentioned in the Text 368

(B.) The Mecanique Celeste 372

JOSEPH FOURIER.

Preliminary Notice 374

Birth of Fourier.--His Youth 377

Memoir on the Resolution of Numerical Equations 380

Part played by Fourier in our Revolution.--His Entrance
into the Corps of Professors of the Normal School and
the Polytechnic School.--Expedition to Egypt 384

Fourier Prefect of L'Isere 405

Mathematical Theory of Heat 408

Central Heat of the Terrestrial Globe 419

Return of Napoleon from Elba.--Fourier Prefect of the
Rhone.--His Nomination to the Office of Director of the
Board of Statistics of the Seine 430

Entrance of Fourier into the Academy of Sciences.--His
Election to the Office of Perpetual Secretary.--His Admission
to the French Academy 437

Character of Fourier.--His Death 438

LIVES

OF

DISTINGUISHED SCIENTIFIC MEN.

THE HISTORY OF MY YOUTH:

AN AUTOBIOGRAPHY OF FRANCIS ARAGO.

I have not the foolish vanity to imagine that any one, even a short time
hence, will have the curiosity to find out how my first education was
given, and how my mind was developed; but some biographers, writing off
hand and without authority, having given details on this subject utterly
incorrect, and of a nature to imply negligence on the part of my
parents, I consider myself bound to put them right.

I was born on the 26th of February, 1786, in the commune of Estagel, an
ancient province of Roussillon (department of the Eastern Pyrenees). My
father, a licentiate in law, had some little property in arable land, in
vineyards, and in plantations of olive-trees, the income from which
supported his numerous family.

I was thus three years old in 1789, four years old in 1790, five years
in 1791, six years in 1792, and seven years old in 1793, &c.

The reader has now himself the means of judging whether, as has been
said, and even stated in print, I had a hand in the excesses of our
first revolution.

My parents sent me to the primary school in Estagel, where I learnt the
rudiments of reading and writing. I received, besides, in my father's
house, some private lessons in vocal music. I was not otherwise either
more or less advanced than other children of my age. I enter into these
details merely to show how much mistaken are those who have printed that
at the age of fourteen or fifteen years I had not yet learnt to read.

Estagel was a halting-place for a portion of the troops who, coming from
the interior, either went on to Perpignan, or repaired direct to the
army of the Pyrenees. My parents' house was therefore constantly full of
officers and soldiers. This, joined to the lively excitement which the
Spanish invasion had produced within me, inspired me with such decided
military tastes, that my family was obliged to have me narrowly watched
to prevent my joining by stealth the soldiers who left Estagel. It often
happened that they caught me at a league's distance from the village,
already on my way with the troops.

On one occasion these warlike tastes had nearly cost me dear. It was the
night of the battle of Peires-Tortes. The Spanish troops in their
retreat had partly mistaken their road. I was in the square of the
village before daybreak; I saw a brigadier and five troopers come up,
who, at the sight of the tree of liberty, called out, "_Somos
perdidos!_" I ran immediately to the house to arm myself with a lance
which had been left there by a soldier of the _levee en masse_, and
placing myself in ambush at the corner of a street, I struck with a blow
of this weapon the brigadier placed at the head of the party. The wound
was not dangerous; a cut of the sabre, however, was descending to punish
my hardihood, when some countrymen came to my aid, and, armed with
forks, overturned the five cavaliers from their saddles, and made them
prisoners. I was then seven years old.[1]

My father having gone to reside at Perpignan, as treasurer of the mint,
all the family quitted Estagel to follow him there. I was then placed as
an out-door pupil at the municipal college of the town, where I occupied
myself almost exclusively with my literary studies. Our classic authors
had become the objects of my favourite reading. But the direction of my
ideas became changed all at once by a singular circumstance which I will
relate.

Walking one day on the ramparts of the town, I saw an officer of
engineers who was directing the execution of the repairs. This officer,
M. Cressac, was very young; I had the hardihood to approach him, and to
ask him how he had succeeded in so soon wearing an epaulette. "I come
from the Polytechnic School," he answered. "What school is that?" "It is
a school which one enters by an examination." "Is much expected of the
candidates?" "You will see it in the programme which the Government
sends every year to the departmental administration; you will find it
moreover in the numbers of the journal of the school, which are in the
library of the central school."

I ran at once to the library, and there, for the first time, I read the
programme of the knowledge required in the candidates.

From this moment I abandoned the classes of the central school, where I
was taught to admire Corneille, Racine, La Fontaine, Moliere, and
attended only the mathematical course. This course was entrusted to a
retired ecclesiastic, the Abbe Verdier, a very respectable man, but
whose knowledge went no further than the elementary course of La Caille.
I saw at a glance that M. Verdier's lessons would not be sufficient to
secure my admission to the Polytechnic School; I therefore decided on
studying by myself the newest works, which I sent for from Paris. These
were those of Legendre, Lacroix, and Garnier. In going through these
works I often met with difficulties which exceeded my powers; happily,
strange though it be, and perhaps without example in all the rest of
France, there was a proprietor at Estagel, M. Raynal, who made the study
of the higher mathematics his recreation. It was in his kitchen, whilst
giving orders to numerous domestics for the labours of the next day,
that M. Raynal read with advantage the "Hydraulic Architecture" of
Prony, the "Mecanique Analytique," and the "Mecanique Celeste." This
excellent man often gave me useful advice; but I must say that I found
my real master in the cover of M. Garnier's "Treatise on Algebra." This
cover consisted of a printed leaf, on the outside of which blue paper
was pasted. The reading of the page not covered made me desirous to know
what the blue paper hid from me. I took off this paper carefully, having
first damped it, and was able to read underneath it the advice given by
d'Alembert to a young man who communicated to him the difficulties which
he met with in his studies: "Go on, sir, go on, and conviction will come
to you."

This gave me a gleam of light; instead of persisting in attempts to
comprehend at first sight the propositions before me, I admitted their
truth provisionally; I went on further, and was quite surprised, on the
morrow, that I comprehended perfectly what overnight appeared to me to
be encompassed with thick clouds.

I thus made myself master, in a year and a half, of all the subjects
contained in the programme for admission, and I went to Montpellier to
undergo the examination. I was then sixteen years of age. M. Monge,
junior, the examiner, was detained at Toulouse by indisposition, and
wrote to the candidates assembled at Montpellier that he would examine
them in Paris. I was myself too unwell to undertake so long a journey,
and I returned to Perpignan.

There I listened for a moment to the solicitations of my family, who
pressed me to renounce the prospects which the Polytechnic School
opened. But my taste for mathematical studies soon carried the day; I
increased my library with Euler's "Introduction a l'Analyse
Infinitesimale," with the "Resolution des Equations Numeriques," with
Lagrange's "Theorie des Fonctions Analytiques," and "Mecanique
Analytique," and finally with Laplace's "Mecanique Celeste." I gave
myself up with great ardour to the study of these books. From the
journal of the Polytechnic School containing such investigations as
those of M. Poisson on Elimination, I imagined that all the pupils were
as much advanced as this geometer, and that it would be necessary to
rise to this height to succeed.

From this moment, I prepared myself for the artillery service,--the aim
of my ambition; and as I had heard that an officer ought to understand
music, fencing, and dancing, I devoted the first hours of each day to
the cultivation of these accomplishments.

The rest of the time I was seen walking in the moats of the citadel of
Perpignan, seeking by more or less forced transitions to pass from one
question to another, so as to be sure of being able to show the examiner
how far my studies had been carried.[2]

At last the moment of examination arrived, and I went to Toulouse in
company with a candidate who had studied at the public college. It was
the first time that pupils from Perpignan had appeared at the
competition. My intimidated comrade was completely discomfited. When I
repaired after him to the board, a very singular conversation took
place between M. Monge (the examiner) and me.

"If you are going to answer like your comrade, it is useless for me to
question you."

"Sir, my comrade knows much more than he has shown; I hope I shall be
more fortunate than he; but what you have just said to me might well
intimidate me and deprive me of all my powers."

"Timidity is always the excuse of the ignorant; it is to save you from
the shame of a defeat that I make you the proposal of not examining
you."

"I know of no greater shame than that which you now inflict upon me.
Will you be so good as to question me? It is your duty."

"You carry yourself very high, sir! We shall see presently whether this
be a legitimate pride."

"Proceed, sir; I wait for you."

M. Monge then put to me a geometrical question, which I answered in such
a way as to diminish his prejudices. From this he passed on to a
question in algebra, then the resolution of a numerical equation. I had
the work of Lagrange at my fingers' ends; I analyzed all the known
methods, pointing out their advantages and effects; Newton's method, the
method of recurring series, the method of depression, the method of
continued fractions,--all were passed in review; the answer had lasted
an entire hour. Monge, brought over now to feelings of great kindness,
said to me, "I could, from this moment, consider the examination at an
end. I will, however, for my own pleasure, ask you two more questions.
What are the relations of a curved line to the straight line that is a
tangent to it?" I looked upon this question as a particular case of the
theory of osculations which I had studied in Legrange's "Fonctions
Analytiques." "Finally," said the examiner to me, "how do you determine
the tension of the various cords of which a funicular machine is
composed?" I treated this problem according to the method expounded in
the "Mecanique Analytique." It was clear that Lagrange had supplied all
the resources of my examination.

I had been two hours and a quarter at the board. M. Monge, going from
one extreme to the other, got up, came and embraced me, and solemnly
declared that I should occupy the first place on his list. Shall I
confess it? During the examination of my comrade I had heard the
Toulousian candidates uttering not very favourable sarcasms on the
pupils from Perpignan; and it was principally for the sake of reparation
to my native town that M. Monge's behaviour and declaration transported
me with joy.

Having entered the Polytechnic School, at the end of 1803, I was placed
in the excessively boisterous brigade of the Gascons and Britons. I
should have much liked to study thoroughly physics and chemistry, of
which I did not even know the first rudiments; but the behaviour of my
companions rarely left me any time for it. As for analysis, I had
already, before entering the Polytechnic School, learnt much more than
was required for leaving it.

I have just related the strange words which M. Monge, junior, addressed
to me at Toulouse in commencing my examination for admission. Something
analogous occurred at the opening of my examination in mathematics for
passing from one division of the school to another. The examiner, this
time, was the illustrious geometer Legendre, of whom, a few years after,
I had the honour of becoming the colleague and the friend.

I entered his study at the moment when M. T----, who was to undergo his
examination before me, having fainted away, was being carried out in the
arms of two servants. I thought that this circumstance would have moved
and softened M. Legendre; but it had no such effect "What is your name,"
he said to me sharply. "Arago," I answered. "You are not French then?"
"If I was not French I should not be before you; for I have never heard
of any one being admitted into the school unless his nationality had
been proved." "I maintain that he is not French whose name is Arago." "I
maintain, on my side, that I am French, and a very good Frenchman too,
however strange my name may appear to you." "Very well; we will not
discuss the point farther; go to the board."

I had scarcely taken up the chalk, when M. Legendre, returning to the
first subject of his preoccupations, said to me: "You were born in one
of the departments recently united to France?" "No, sir; I was born in
the department of the Eastern Pyrenees, at the foot of the Pyrenees."
"Oh! why did you not tell me that at once? all is now explained. You are
of Spanish origin, are you not?" "Possibly; but in my humble family
there are no authentic documents preserved which could enable me to
trace back the civil position of my ancestors; each one there is the
child of his own deeds. I declare to you again that I am French, and
that ought to be sufficient for you."

The vivacity of this last answer had not disposed M. Legendre in my
favour. I saw this very soon; for, having put a question to me which
required the use of double integrals, he stopped me, saying: "The method
which you are following was not given to you by the professor. Whence
did you get it?" "From one of your papers." "Why did you choose it? was
it to bribe me?" "No; nothing was farther from my thoughts. I only
adopted it because it appeared to me preferable." "If you are unable to
explain to me the reasons for your preference, I declare to you that you
shall receive a bad mark, at least as to character."

I then entered upon the details which established, as I thought, that
the method of double integrals was in all points more clear and more
rational than that which Lacroix had expounded to us in the
amphitheatre. From this moment Legendre appeared to me to be satisfied,
and to relent.

Afterwards, he asked me to determine the centre of gravity of a
spherical sector. "The question is easy," I said to him. "Very well;
since you find it easy, I will complicate it: instead of supposing the
density constant, I will suppose that it varies from the centre to the
surface according to a determined function." I got through this
calculation very happily; and from this moment I had entirely gained the
favour of the examiner. Indeed, on my retiring, he addressed to me these
words, which, coming from him, appeared to my comrades as a very
favourable augury for my chance of promotion: "I see that you have
employed your time well; go on in the same way the second year, and we
shall part very good friends."

In the mode of examination adopted at the Polytechnic School in 1804,
which is always cited as being better than the present organization,
room was allowed for the exercise of some unjustifiable caprices. Would
it be believed, for example, that the old M. Barruel examined two pupils
at a time in physics, and gave them, it is said, the same mark, which
was the mean between the actual merits of the two? For my part, I was
associated with a comrade full of intelligence, but who had not studied
this branch of the course. We agreed that he should leave the answering
to me, and we found the arrangement advantageous to both.

As I have been led to speak of the school as it was in 1804, I will say
that its faults were less those of organization than those of personal
management; for many of the professors were much below their office, a
fact which gave rise to somewhat ridiculous scenes. The pupils, for
instance, having observed the insufficiency of M. Hassenfratz, made a
demonstration of the dimensions of the rainbow, full of errors of
calculation, but in which the one compensated the other so that the
final result was true. The professor, who had only this result whereby
to judge of the goodness of the answer, when he saw it appear on the
board, did not hesitate to call out, "Good, good, perfectly good!" which
excited shouts of laughter on all the benches of the amphitheatre.

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