See also:

• JEAN

JEAN See also:

• BERNARD, CHARLES DE
• BERNARD, CLAUDE (1813-1878)
• BERNARD, JACQUES (1658--1718)
• BERNARD, MOUNTAGUE (1S2o—1882)
• BERNARD, SAINT
• BERNARD, SAINT (Iogo-1153)
• BERNARD, SIMON (1779—1839)
• BERNARD, SIR THOMAS, BART

BERNARD See also:

• LEON
• LEON, LUIS PONCE DE (1527-1591)
• LEON, MOSES BEN SI
• LEON, or LEON DE LAS ALDAMAS

LEON See also:

• JEAN BERNARD LEON FOUCAULT (1819—1868)

FOUCAULT (1819—1868)  , See also:

• FRENCH
• FRENCH, DANIEL CHESTER (1850– )
• FRENCH, NICHOLAS (1604-1678)

French physicist, was the son of a publisher at See also:

• PARIS
• PARIS (also called ALEXANDROS)
• PARIS, ALEXIS PAULIN (1800-x881)
• PARIS, BRUNO PAULIN GASTON (1839-1903)
• PARIS, FRANCOIS DE (169o-1727)
• PARIS, LOUIS PHILIPPE ALBERT
• PARIS, TREATIES OF (1814-1815)

Paris, where he was See also:

• BORN, IGNAZ, EDLER VON (1742–1791)

born on the 18th of See also:

• SEPTEMBER (Lat. septem, seven)

September 1819 . After an See also:

• EDUCATION

education received chiefly at See also:

• HOME
• HOME, DANIEL DUNGLAS (1833-1886)
• HOME, EARLS OF

home, he studied See also:

• MEDICINE

medicine, which, however, he speedily abandoned for See also:

• PHYSICAL

physical See also:

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

science, the improvement of L . J . M . See also:

• DAGUERRE, LOUIS JACQUES MANDE (1789-1851)

Daguerre's photographic processes being the See also:

• OBJECT

object to which he first directed his See also:

• ATTENTION (from Lat. ad-tendo, await, expect; the condition of being " stretched " or " tense ")

attention . During three years he was experimental assistant to See also:

• ALFRED

Alfred See also:

• DONNE, JOHN (1573–1631)

Donne (1801—1878) in his course of lectures on microscopic See also:

• ANATOMY
• ANATOMY (Gr. avaroyil, from ava-silo c', to cut up)

anatomy . With A . H . L . See also:

• FIZEAU, ARMAND HIPPOLYTE LOUIS (1819–1896)

Fizeau he carried on a See also:

• SERIES (a Latin word from serere, to join)

series of investigations on the intensity of the See also:

• LIGHT

light of the See also:

• SUN
• SUN (0. Eng. sonne, Ger. sonne. Fr. soleil, Lat. sol, Gr. ijXior, from which comes helio- in various English compounds)

sun, as compared with that of See also:

• CARBON (symbol C, atomic weight 12)

carbon in the electric arc, and of See also:

• LIME
• LIME (O. Eng. lim, Lat. limes, mud, from linere, to smear)

lime in the See also:

• FLAME (Lat. flamma; the root flag- appears in flagrare, to burn, blaze, and Gr. d, XEryew)

flame of the oxyhydrogen See also:

• BLOWPIPE

blowpipe; on the interference of See also:

• HEAT (0. E. haktu, which like " hot," Old Eng. hat, is from the Teutonic type haita, hit, to be hot; cf. Ger. hitze, heiss; Dutch, hitte, heet, &c.)

heat rays, and of light rays differing greatly in lengths of path; and on the See also:

• CHROMATIC (Gr. xpcoµaruc6s, coloured, from xpwµa, colour)

chromatic polarization of light . In 1849 he contributed to the Comptes Rendus a description of an electromagnetic regulator for the electric arc See also:

• LAMP (from Gr. Xag ras, a torch, Xaµaav, to shine)

lamp, and, in See also:

• CONJUNCTION (from Lat. conjungere, to join together)

conjunction with H . V .

See also:

• REGNAULT, HENRI (1843-1871)
• REGNAULT, HENRI VICTOR (1810-1878)
• REGNAULT, JEAN BAPTISTE (1754-1829)

Regnault, a See also:

• PAPER
• PAPER (Fr. papier, from Lat. papyrus)

paper on See also:

• BINOCULAR

binocular See also:

• VISION (from Lat. videre, to see), or SIGHT

vision . By the use of a revolving See also:

• MIRROR (through O. Fr. mirour, mod. miroir, from a sup-posed Late Lat. miratorium, from mirari, to admire)

mirror similar to that used by See also:

• SIR

Sir See also:

• CHARLES
• CHARLES (1270-1325)
• CHARLES (1421-1461)
• CHARLES (1525-1574)
• CHARLES (c. 1319-1364)
• CHARLES (Fr. Charles; Span. Carlos; Ital. Carlo; Ger. Karl; derived from O.H.G. Charal,latinized as Carolus, meaning originally " man ": cf. Mod.Ger., Kerl," fellow," A.S. ceorl, Mod. Eng. " churl ")
• CHARLES (KARL EITEL ZEPHYRIN LUDWIG; in Rum. CAROL)
• CHARLES [KARL ALEXANDER] (1712-1780)
• CHARLES, ELIZABETH (1828-1896)
• CHARLES, JACQUES ALEXANDRE CESAR (1746-1823)
• CHARLES, THOMAS (1755-1814)

Charles See also:

• WHEATSTONE, SIR CHARLES (1802–1875)

Wheatstone for measuring the rapidity of electric currents, he was enabled in 185o to demonstrate the greater velocity of light in See also:

• AIR (from an Indo-European root meaning " breathe," " blow ")
• AIR, or ASBEN

air than in See also:

• WATER

water, and to establish that the velocity of light in different See also:

• MEDIA

media is inversely as the refractive indices of the media . For his demonstration in 1851 of the diurnal See also:

• MOTION (Lat. motio, from movere, to move)
• MOTION, LAWS OF

motion of the See also:

• EARTH
• EARTH (a word common to Teutonic languages, cf. Ger. Erde, Dutch aarde, Swed. and Dan. jord; outside Teutonic it appears only in the Gr. 'pq'e, on the ground; it has been connected by some etymologists with the Aryan root ar-, to plough, which is seen in
• EARTH, FIGURE OF
• EARTH, FIGURE OF THE

earth by the rotation of the See also:

• PLANE

plane of oscillation of a freely suspended, See also:

• LONG, GEORGE (1800-1879)
• LONG, JOHN DAVIS (1838– )

long and heavy pendulum exhibited by him at the See also:

• PANTHEON (Lat. pantheum or pantheon; Gr. srav& ov, all-holy, from re, s, all, and Oeor god)

Pantheon in Paris, and again in the following See also:

• YEAR

year by means of his invention the gyroscope, he received the See also:

• COPLEY, JOHN SINGLETON (1737—1815)

Copley See also:

• MEDAL (Fr. medaille, from Lat. metallum)

medal of the Royal Society in 1855, and in the same year he was made physical assistant in the imperial See also:

• OBSERVATORY

observatory at Paris . In September of that year he discovered that the force required for the rotation of a See also:

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

copper disk becomes greater whenit is made to rotate with its rim between the poles of a magnet, the disk at the same See also:

• TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
• TIME, MEASUREMENT OF
• TIME, STANDARD

time becoming heated by the eddy or " See also:

• FOUCAULT, JEAN BERNARD LEON (1819—1868)

Foucault currents " induced in its See also:

• METAL
• METAL (through Fr. from Lat. metallum, mine, quarry, adapted from Gr. µATaXAov, in the same sense, probably connected with ,ueraAAdv, to search after, explore, µeTa, after, aAAos, other)

metal . Foucault invented in 1857 the polarizer which bears his name, and in the succeeding year devised a method of giving to the See also:

• SPECULUM

speculum of reflecting telescopes the See also:

• FORM (Lat. forma)

form of a See also:

• SPHEROID (Gr. c4aipa-etbis, like a sphere)

spheroid or a paraboloid of revolution . With Wheatstone's revolving mirror he in 1862 determined the See also:

• ABSOLUTE (Lat. absolvere, to loose, set free)

absolute velocity of light to be 298,000 kilometres (about 185,000 m.) a second, or ro,000 kilom. less than that obtained by previous experimenters . He was created in that year a member of the See also:

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

Bureau See also:

• DES

des Longitudes and an officer of the See also:

• LEGION (Lat. legio)

Legion of See also:

• HONOUR (Lat. honos or lwnor, honoris; in English the word was spelled with or without the u indifferently until the 17th century, but during the 18th century it became fashion-able to spell the word " honor "; Johnson's and Webster's Dictionaries stereoty

Honour, in 1864 a See also:

• FOREIGN

foreign member of the Royal Society of See also:

• LONDON

London, and next year a member of the See also:

• MECHANICAL

mechanical See also:

• SECTION
• SECTION (Lat. sectio, cutting, secare, to cut)

section of the See also:

• INSTITUTE (from Lat. instituere, to establish or set up)

Institute . In 1865 appeared his papers on a modification of See also:

• WATT, JAMES (1736-1819)

Watt's See also:

• GOVERNOR (from the Fr. gouverneur, from gouverner, O. Fr. governer, Lat. gubernare, to steer a ship, to direct, guide)

governor, upon which he had for some time been experimenting with a view to making its See also:

• PERIOD
• PERIOD (Gr. irepioSos, a going or way round, circuit, aepi, round, and &Sis, way, road)

period of revolution See also:

• CONSTANT, BENJAMIN (1845-1902)

constant, and on a new apparatus for regulating the electric light; and in the following year (See also:

• COMET (Gr. Koµieiis, long-haired)

Comet . Rend. lxiii.) he showed how, by the deposition of a transparently thin film of See also:

• SILVER

silver on the See also:

• OUTER

outer See also:

• SIDE
• SIDE (mod. Eski Adalia)

side of the object See also:

• GLASS
• GLASS (O.E. glees, cf. Ger. Glas, perhaps derived from an old Teutonic root gla-, a variant of glo-, having the general sense of shining, cf. " glare," " glow ")
• GLASS, STAINED

glass of a See also:

• TELESCOPE

telescope, the sun could be viewed without injuring the See also:

• EYE
• EYE (O. Eng. edge, Ger. Auge; derived from an Indo-European root also seen in Lat. oc-ulus, the organ of vision (q.v.)

eye by excess of light . Foucault died of See also:

• PARALYSIS, or PALSY (from Gr. aapal,6a , to relax; Wycliffe has palesy, and another old form of the word is parlesy)

paralysis on the 11th of See also:

• FEBRUARY

February 1868 at Paris . From the year 1845 he edited the scientific portion of the See also:

• JOURNAL
• JOURNAL (through Fr. from late Lat. diurnalis, daily)

Journal des Debts . His See also:

• CHIEF (from Fr. chef, head, Lat. caput)

chief scientific papers are to be found in the Comptes Rendus, 1847—1869 .

See Revue See also:

• TOURS

tours scient. vi . (1869), pp . 484-489; Prot . See also:

• ROY, WILLIAM (1726-1790)

Roy . See also:

• SOC

Soc. xvii . (1869), pp. lxxxiii.-lxxxiv.; Lissajous, See also:

• NOTICE

Notice historique sur la See also:

• VIE

vie et See also:

• LES

les travaux de See also:

• LEON
• LEON, LUIS PONCE DE (1527-1591)
• LEON, MOSES BEN SI
• LEON, or LEON DE LAS ALDAMAS

Leon Foucault (Paris, 1875) .