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amnesty of 1859. In 1879 he was nominated director of the Luxembourg museum. Showing decided military tastes Francois Arago was sent to the municipal See also:

COLLEGE (Collegium)

college of Perpignan, where he began to study See also:

MATHEMATICS (Gr. /saBnµar1Kil, Sc. vOcvn or E7rlQTt'µn; from p iN.La, "learning" or "science ")

mathematics in preparation for the entrance examination of the See also:

POLYTECHNIC (Gr. aroWus, many, and rEXvn, an art)

polytechnic school. Within two years and a See also:

HALF

half he had mastered all the subjects prescribed for examination, and a great See also:

DEAL

deal more, and, on going up for examination at See also:

Toulouse, he astounded his examiner by his knowledge of See also:

LAGRANGE, JOSEPH LOUIS (1736-1813)

Lagrange. Towards the See also:

close of 1803 he entered the polytechnic school, with the See also:

ARTILLERY (the O. Fr. artiller, to equip with engines of war, probably comes from Late Lat. articulum, dim. of ars, art, cf. " engine " from ingenium, or of artus, joint)

artillery service as the aim of his ambition, and in 1804, through the See also:

ADVICE (Fr. avis, from Lat. ad, to, and visum, viewed)

advice and recommendation of S. D.

See also:

POISSON, SIMEON DENIS (1781-1840)

Poisson, he received the See also:

APPOINTMENT, POWER OF

appointment of secretary to the See also:

OBSERVATORY

Observatory of See also:

Paris. He now became acquainted with See also:

LAPLACE, PIERRE SIMON, MARQUIS DE (1749—1827)

Laplace, and through his See also:

INFLUENCE (Late Lat. influentia, from influere, to flow in)

influence was commissioned, with J. B. See also:

BIOT, JEAN BAPTISTE (1774-1862)

Biot, to See also:

COMPLETE

complete the meridional measurements which had been begun by J. B. J. See also:

DELAMBRE, JEAN BAPTISTE JOSEPH (1749-1822)

Delambre, and interrupted since the See also:

DEATH

death of P. F. A. Mechain (1744-1804). The two See also:

LEFT

left Paris in 1806 and began operations among the mountains of See also:

Spain, but Biot returned to Paris after they had determined the See also:

LATITUDE (Lat. latitudo, latus, broad)

latitude of Forrnentera, the southernmost point to which they were to carry the survey,leaving Arago to make the geodetical connexion of See also:

MAJORCA (Mallorca)

Majorca with Ivica and with Formentera. The adventures and difficulties of the latter were now only beginning.

The See also:

POLITICAL

political ferment caused by the entrance of the French into Spain extended to these islands, and the ignorant populace began to suspect that Arago's movements and his blazing fires on the See also:

TOP (cf. Dan. top, Ger. Topf, also meaning pot)

top of See also:

MOUNT, WILLIAM SIDNEY (1807-1868)

Mount Galatzo were telegraphic signals to the invading army. Ultimately they became so infuriated that he was obliged to cause himself to be incarcerated in the fortress of Belver in See also:

JUNE

June 18o8. On the 28th of See also:

JULY

July he managed to See also:

ESCAPE (in mid. Eng. eschape or escape, from the O. Fr. eschapper, modern echapper, and escaper, low Lat. escapium, from ex, out of, and cappa, cape, cloak; cf. for the sense development the Gr. iichueoOat, literally to put off one's clothes, hence to sli

escape from the See also:

ISLAND (O.E. ieg =isle, +land')

island in a fishing-See also:

BOAT (0. Eng. bdt; the true etymological connexion with Dutch and Ger. boot, Fr. bateau, Ital. battello presents great difficulties; Celtic forms are from O. Eng.)

boat, and after an adventurous voyage he reached See also:

ALGIERS (Fr. Alger, Arab. Jezair, i.e. The Islands)

Algiers on the 3rd of See also:

AUGUST (originally Sextilis)

August. Thence he procured a passage in a See also:

VESSEL (O. Fr. vaissel, from a rare Lat. vascellum, dim. of vas, vase, urn)

vessel See also:

BOUND, or BOUNDARY (from O. Fr. bonde, Med. Lat. bodena or butina, a frontier line)

bound for See also:

MARSEILLES

Marseilles, but on the 16th of August, just as the vessel was nearing Marseilles, it See also:

fell into the hands of a See also:

SPANISH

Spanish See also:

CORSAIR (through the Fr. from the Med. Lat. cursarius, a pirate; cursus, or cursa, from currere, to run, being Late Latin for a plundering foray)

corsair. With the See also:

REST (O. Eng. rest, reste, bed, cognate with other Teutonic forms, e.g. Ger. Rast, Riiste, rest, and probably Gothic Rasta, league, i.e. resting or stopping place)

rest of the See also:

crew, Arago was taken to See also:

ROSAS, JUAN MANUEL (1793-1877)

Rosas, and imprisoned first in a See also:

WINDMILL

windmill, and afterwards in the fortress of that seaport, until the See also:

TOWN

town fell into the hands of the French, when the prisoners were transferred to Palamos. After fully three months' imprisonment they were released on the demand of the See also:

DEY (an adaptation of the Turk. dai, a maternal uncle)

dey of Algiers, and again set See also:

SAIL

sail for Marseilles on the 28th of See also:

NOVEMBER (Lat. novem, nine)

November, but when within sight of their See also:

PORT

port they were driven back by a northerly See also:

wind to See also:

BOUGIE

Bougie on the See also:

COAST (from Lat. costa, a rib, side)

coast of See also:

Africa. Transport to Algiers by See also:

sea from this See also:

PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place would have occasioned a weary stay of three months; Arago, therefore, set out for it by See also:

LAND

land under conduct of a See also:

MAHOMMEDAN

Mahommedan See also:

PRIEST (Ger. Priester, Fr. pretre)

priest, and reached it on See also:

CHRISTMAS (i.e. the Mass of Christ)

Christmas See also:

day. After six months' stay in Algiers he once again, on the 21st of June 1809, set sail for Marseilles, where he had to undergo a monotonous and inhospitable See also:

QUARANTINE (Fr. quarantaine, a period of forty days 1)

quarantine in the See also:

LAZARETTO

lazaretto, before his difficulties were over. The first See also:

LETTER (through Fr. lettre from Lat. littera or litera, letter of the alphabet; the origin of the Latin word is obscure; it has probably no connexion with the root of linere, to smear, i.e. with wax, for an inscription with a stilus)

letter he received, while in the lazaretto, was from A. von See also:

Humboldt; and this was the origin of a connexion which, in Arago's words, " lasted over See also:

FORTY

forty years without a single See also:

CLOUD (from the same root, if not the same word, as " clod," a word common in various forms to Teutonic languages for a mass or lump; it is first applied in the usual sense in the late 13th century; the Anglo-Saxon chid is only used in the sense of " a ma

cloud ever having troubled it." Through all these vicissitudes Arago had succeeded in preserving the records of his survey ; and his first See also:

ACT (Lat. actus, actum)

act on his return See also:

home was to See also:

DEPOSIT (Lat. depositurn, from deponere, to lay down, to put in the care of)

deposit them in the See also:

BUREAU (a Fr. word from burel or bureau, a coarse cloth used for coverings)

Bureau See also:

des Longitudes at Paris. As a See also:

REWARD

reward for his adventurous conduct in the cause of See also:

SCIENCE (Lat. scientia, from scire; to learn, know)

science, he was in See also:

SEPTEMBER (Lat. septem, seven)

September 1809 elected a member of the See also:

Academy of Sciences, in See also:

ROOM

room of J. B. L.

See also:

LALANDE, JOSEPH JEROME LEFRANCAIS DE (1732-1807)

Lalande, at the remarkably See also:

early See also:

AGE (Fr. age, through late Lat. aetaticum, from aetas)

age of twenty-three, and before the close of the same See also:

YEAR

year he was chosen by the See also:

COUNCIL (Lat. concilium, from cum, together, and the root cal, to call)

council of the polytechnic school to succeed G. See also:

MONGE, GASPARD (1746-1818)

Monge in the See also:

CHAIR (in. Mid. Eng. chcere, through O. Fr. chaire or chaiere, from Lat. cathedra, later caledra, Gr. xaOi3pa, seat, cf. "cathedral"; the modern Fr. form chaise, a chair, has been adopted in English with a particular meaning as a form of carriage; chaire

chair of See also:

ANALYTICAL

analytical See also:

GEOMETRY

geometry. About the same See also:

time he was named by the See also:

EMPEROR (Fr. empereur, from the Lat. imperator)

emperor one of the astronomers of the Royal Observatory, which was accordingly his See also:

RESIDENCE (Latin residere, to remain behind, to dwell, reside)

residence till his death, and it was in this capacity that he delivered his remarkably successful See also:

SERIES (a Latin word from serere, to join)

series of popular lectures on See also:

ASTRONOMY (from Gr. &arpov, a star, and v ,usiv, to classify or arrange)

astronomy, which were continued from 1812 to 1845. In 1816, along with See also:

Gay-Lussac, he started the Annales de chimie et de physique, and in 1818 or 1819 he proceeded along with Biot to execute See also:

GEODETIC

geodetic operations on the coasts of France, See also:

England and See also:

Scotland. They measured the length of the seconds-pendulum at See also:

LEITH

Leith, and in Unst, one of the See also:

SHETLAND, or ZETLAND

Shetland isles, the results of the observations being published in 1821, along with those made in Spain. Arago was elected a member of the See also:

BOARD (O. Eng. bord)

Board' of See also:

LONGITUDE (from Lat. longitudo, " length ")

Longitude immediately afterwards, and contributed to each of its Annuals, for about twenty-two years, important scientific notices on astronomy and See also:

METEOROLOGY (Gr. JerEwpa, and hb'yos, i.e. the science of things in the air)

meteorology and occasionally on See also:

CIVIL

civil See also:

ENGINEERING

engineering, as well as interesting See also:

MEMOIRS

memoirs of members of the Academy. In 183o, Arago, who always professed liberal opinions of the extreme republican type, was elected a member of the chamber of deputies for the See also:

LOWER

Lower See also:

Seine, and he employed his splendid gifts of eloquence and scientific knowledge in all questions connected with public See also:

EDUCATION

education, the rewards of inventors, and the encouragement of the See also:

MECHANICAL

mechanical and See also:

PRACTICAL

practical sciences. Many of the most creditable See also:

NATIONAL

national enterprises, dating from this See also:

period, are due to his advocacy—such as the reward to L. J. M. See also:

DAGUERRE, LOUIS JACQUES MANDE (1789-1851)

Daguerre for the invention of . See also:

photography, the See also:

grant for the publication of the See also:

WORKS

works of P. See also:

FERMAT, PIERRE DE (1601-1665)

Fermat and Laplace, the acquisition of the museum of See also:

CLUNY, or CLUGNY

Cluny, the development of See also:

RAILWAYS

railways and electric telegraphs, the improvement of the See also:

NAVIGATION (from Lat. navis, ship, and agere, to move)

navigation of the Seine, and the See also:

BORING

boring of the artesian See also:

wells at Grenelle.

In the year 183o also he was appointed director of the Observatory, and as a member of the chamber of deputies he was able to obtain grants of See also:

MONEY

money for rebuilding it in part, and for the addition of magnificent See also:

INSTRUMENTS

instruments. In the same year, too, he was chosen perpetual secretary of the Academy of Sciences, in room of J. B. J. See also:

Fourier. Arago threw his whole soul into its service, and by his See also:

FACULTY (through the French, from the Lat. facultas, ability to do anything, from facilis, easy, facere, to do; another form of the word in Lat. facilitas, facility, ease, keeps the original meaning)

faculty of making See also:

friends he gained at once for it and for himself a See also:

WORLD

world-wide reputation. As perpetual secretary it fell to him to pronounce See also:

HISTORICAL

historical doges on deceased members; and for this See also:

DUTY (from " due," that which is owing, O. Fr. deu, dil, past participle of devoir; Lat. debere, debitum; cf. " debt ")

duty his rapidity and facility of thought, his happy piquancy of See also:

style, and his extensive knowledge peculiarly adapted him. In 1834 he again visited England, to attend the See also:

MEETING (from " to meet," to come together, assemble, 0. Eng. metals ; cf. Du. moeten, Swed. mota, Goth. gamotjan, &c., derivatives of the Teut. word for a meeting, seen in O. Eng. Wit, moot, an assembly of the people; cf. witanagemot)

meeting of the See also:

BRITISH

British Association at See also:

EDINBURGH

Edinburgh. From this time till 1848 he led a See also:

LIFE

life of See also:

COMPARATIVE

comparative quiet—not the quiet of inactivity, however, for his incessant labours within the Academy and the Observatory produced a multitude of contributions to all departments of See also:

PHYSICAL

physical science,—but on the fall of See also:

Louis Philippe he left his laboratory to join in forming the provisional See also:

government. He was entrusted with the See also:

DISCHARGE (adapted from the O. Fr. discharge, modern decharge, from a med. Lat. discargare, to unload, dis- and earn care, to load, cf. " charge ")

discharge of two important functions, that had never before been See also:

UNITED

united in one See also:

PERSON, OFFENCES AGAINST THE

person, viz. the See also:

MINISTRY

ministry of See also:

war and of marine; and in the latter capacity he effected some salutary reforms, such as the improvement of rations in the See also:

NAVY

navy and the abolition of flogging. He also abolished political oaths of all kinds, and, against an See also:

ARRAY (from the O. Fr. areyer, Med. Lat. arredare, to get ready)

array of moneyed interests, succeeded in procuring the abolition of See also:

NEGRO (from Lat. eager, black)

negro See also:

SLAVERY

slavery in the French colonies. In the beginning of May 1852, when the government of Louis See also:

NAPOLEON

Napoleon required an See also:

OATH (0. Eng. ddh)

oath of See also:

ALLEGIANCE (Mid. Eng. ligeaunce; med. Lat. ligeantia, &c.; the al- was probably added through confusion with another legal term, allegeance, an allegation; the Fr. allegeance comes from the English; the word is formed from " liege," of which the derivatio

allegiance from all its functionaries, Arago peremptorily refused, and sent in his resignation of his See also:

POST

post as astronomer at the Bureau des Longitudes.

This, however, the See also:

prince See also:

PRESIDENT (Fr. president, from Lat. praesidens, post-Augustan Lat. for praeses, director, ruler, from praesidere, to sit in front of, preside)

president, to his See also:

CREDIT (Lat. credere, to believe)

credit, declined to accept, and made " an exception in favour of a savant whose works had thrown lustre on France, and whose existence his government would regret to embitter." But the See also:

TENURE (Fr. tenure, from Lat. tenere, to hold)

tenure of See also:

OFFICE (from Lat. officium, " duty," " service," a shortened form of opifacium, from facere, " to do," and either the stem of opes, " wealth," " aid," or opus, " work ")

office thus granted did not prove of See also:

long duration. Arago was now on his death-See also:

bed, under a complication of diseases, induced, no doubt, by the hardships and labours of his earlier years. In the summer of 1853 he was advised by his physicians to try the effect of his native See also:

air, and he accordingly set out for the eastern Pyrenees. But the See also:

CHANGE (derived through the Fr. from the Late Lat. cambium, cambiare, to barter; the ultimate derivation is probably from the root which appears in the Gr. «a urmu', to bend)

change was unavailing, and after a lingering illness, in which he suffered first from See also:

DIABETES (from Gr. &a, through, and faivecv, to pass)

diabetes, then from See also:

Bright's disease, complicated by See also:

DROPSY (contracted from the old word hydropisy, derived from the Gr. 154w¢; i Swp, water, and appearance)

dropsy, he died in Paris on the 2nd of See also:

OCTOBER

October 1853. Arago's fame as an experimenter and discoverer rests mainly on his contributions to See also:

magnetism and still more to See also:

OPTICS

optics. He found that a magnetic See also:

NEEDLE (O. Eng. ncedl; the word appears in various forms in Teutonic languages, Ger. Nadel, Dutch naal, the root being ne-, to sew, cf. Ger. nahen, and probably Lat. nere, to spin, Gr. vi)ats, spinning)

needle, made to oscillate over non-ferruginous surfaces, such as See also:

WATER

water, See also:

glass, See also:

COPPER (symbol Cu, atomic weight 63.1, H=1, or 63.6, O = 16)

copper, &c., falls more rapidly in the extent of its oscillations according as it is more or less approached to the See also:

SURFACE

surface. This See also:

DISCOVERY

discovery, which gained him the See also:

COPLEY, JOHN SINGLETON (1737—1815)

Copley See also:

MEDAL (Fr. medaille, from Lat. metallum)

medal of the Royal Society in 1825, was followed by another, that a rotating See also:

PLATE

plate of copper tends to communicate its See also:

motion to a magnetic needle suspended over it (" magnetism of rotation "). Arago is also fairly entitled to be regarded as having proved the long-suspected connexion between the See also:

aurora borealis and the See also:

variations of the magnetic elements. In optics we owe to him not only important See also:

OPTICAL

optical discoveries of his own, but the credit of stimulating the See also:

GENIUS (from Lat. genere, gignere)

genius of A. J. See also:

FRESNEL, AUGUSTIN JEAN (1788-1827)

Fresnel, with whose See also:

HISTORY

history, as well as with that of E. L.

See also:

MALUS, ETIENNE LOUIS (1775-1812)

Malus and of See also:

Thomas See also:

Young, this part of his life is closely interwoven. Shortly after the beginning of the 19th See also:

CENTURY (from Lat. centuria, a division of a hundred men)

century the labours of these three philosophers were shaping the See also:

MODERN

modern See also:

DOCTRINE

doctrine of the undulatory theory of light. Fresnel's arguments in favour of that theory found little favour with Laplace, Poisson and Biot, the champions of the emission theory; but they were ardently espoused by Humboldt and by Arago, who had been appointed by the Academy to See also:

REPORT (O.Fr. report or raport, modern rapport, from O.Fr. reporter, mod. rap porter, Lat. reportare, to bring back, in poetical use only, of bringing back an account, news, &c.)

report on the See also:

paper. This was the See also:

FOUNDATION (Lat. fundatio, from fundare, to found)

foundation of an intimate friendship between Arago and Fresnel, and of a determination to carry on together furtherresearches in this subject, which led to the enunciation of the fundamental See also:

LAWS

laws of the polarization of light known by their names (see POLARIZATION). As a result of this See also:

WORK

work Arago constructed a polariscope, which he used for some interesting observations on the polarization of the light of the See also:

SKY (M. Eng. skie, cloud; O. Eng. skua, shade; connected with an Indo-European root sku, cover, whence " scum," Lat. obscurus, dark, &c.)

sky. To him is also due the discovery of the See also:

POWER [WILLIAM GRATTAN] TYRONE (1797-1841)

power of rotatory polarization exhibited by See also:

QUARTZ

quartz, and last of all, among his many contributions to the support of the undulatory See also:

HYPOTHESIS (from Gr. inrorcOivat, to put under; cf. Lat. suppositio, from sub-ponere)

hypothesis, comes the experimentum crucis which he proposed to carry out for comparing directly the velocity of light in air and in water or glass. On the emission theory the velocity should be accelerated by an increase of See also:

DENSITY (Lat. densus, thick)

density in the See also:

MEDIUM

medium; on the See also:

WAVE

wave theory, it should be retarded. In 1838 he communicated to the Academy the details of his apparatus, which utilized the revolving mirrors employed by See also:

Sir C. See also:

WHEATSTONE, SIR CHARLES (1802–1875)

Wheatstone in 1835 for measuring the velocity of the electric discharge; but owing to the great care required in the carrying out of the project, and to the interruption to his labours caused by the revolution of 1848, it was the See also:

SPRING (from " to spring," " to leap or jump up," " burst out," O. Eng., springau, a common Teut. word, cf. Ger. springer, possibly allied to Gr. QnrFpxecOac, to move rapidly)

spring of 185o before he was ready to put his See also:

IDEA (Gr. Ibia, connected with i&eiv, to see; cf. Lat. species from specere, to look at)

idea to the test; and then his eyesight suddenly gave way. Before his death, however, the retardation of light in denser See also:

MEDIA

media was demonstrated by the experiments of H. L. See also:

FIZEAU, ARMAND HIPPOLYTE LOUIS (1819–1896)

Fizeau and J.

B. L. See also:

FOUCAULT, JEAN BERNARD LEON (1819—1868)

Foucault, which, with improvements in detail, were based on the See also:

plan proposed by him. Arago's fEuvres were published after his death under the direction of J. A. See also:

BARRA, or BARRAY (Scand. Baraey, isle of the ocean)

Barra!, in 17 vols., 8vo, 1854–1862; also separately his Astronomie populaire, in 4 vols. ; Notices biographiques, in 3 vols. ; Notices scientifiques, in 5 vols. ; Voyages scientifiques, in i vol. ; Memoires scientifiques, in 2 vols. ; Melanges, in I vol. ; and Tables analytiques et documents importants (with portrait), in I vol.

See also:

ENGLISH

English See also:

TRANSLATIONS

translations of the following portions of his works have appeared :—Treatise on Comets, by C. See also:

Gold, C.B. (See also:

LONDON

London, 1833) ; also translated by See also:

Smyth and Grant (London, 1861) ; Hist. iloge of See also:

James See also:

WATT, JAMES (1736-1819)

Watt, by James Muirhead (London, 1839); also translated, with notes, by See also:

Lord See also:

Brougham; Popular Lectures on Astronomy, by See also:

Walter See also:

Kelly and Rev. L. Tomlinson (London, 1854) ; also translated by Dr W. H. Smyth and Prof. R. Grant, 2 vols. (London, 1855) ; Arago's Auto-See also:

BIOGRAPHY (from the Gr. (3ios, life, and yp&4 , writing)

biography, translated by the Rev. See also:

Baden See also:

Powell (London, 1855, 1858); Arago's Meteorological Essays, with introduction by Humboldt, translated under the superintendence of See also:

COLONEL (derived either from Lat. column, Fr. colonne, column, or Lat. corona, a crown)

Colonel See also:

SABINE, SIR EDWARD (1788-1883)

Sabine (London, 1855), and Arago's See also:

BIOGRAPHIES

Biographies of Scientific Men, translated by Smyth, Powell and Grant, 8vo (London, 1857).

End of Article: ARAGO, DOMINIQUE FRANCOIS JEAN (1786-1853)

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