See also:

• ECLIPSE (Gr. €uheo,tis, falling out of place, failing)

ECLIPSE (Gr. €uheo,tis, falling out of See also:

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

place, failing)  , the See also:

• COMPLETE

complete or partial obscuration of one heavenly See also:

• BODY

body by the See also:

• SHADOW (0. Eng. Schadewe, sceadu; a form of " shade "; connected with Gr. 6-Ore's, darkness)

shadow of another, or of the disk 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 by the inter-position of the See also:

• MOON (a common Teutonic word, cf. Ger. Mond, Du. maan, Dan. maane, &c., and cognate with such Indo-Germanic forms as Gr. µlip, Sans. ma's, Irish mi, &c.; Lat. uses luna, i.e. lucna, the shining one, lucere, to shine, for the moon, but preserves the word i
• MOON, SIR RICHARD, 1ST BARONET (1814-1899)

moon; then called an See also:

• ECLIPSE (Gr. €uheo,tis, falling out of place, failing)

eclipse of the sun . Eclipses are of three classes: those of the sun, as just defined; those of the moon, produced by its passage through the C shadow 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, and those of the satellites of other See also:

• PLANETS, MINOR

planets, produced by their passage through the shadow of their See also:

• PRIMARY

primary . See also:

• JUPITER

Jupiter (q.v.) is the only See also:

• PLANET (Gr. ssXavirrns, a wanderer)

planet of whose satellites the eclipses can be observed, unless under very rare circumstances . The geometrical conditions of an eclipse of the sun or moon are shown in fig . 1, which represents the earth E as casting its shadow towards C, and the moon M between the earth and sun as throwing its shadow towards some See also:

• PART

part of the earth and eclipsing the sun . The dark conical regions are those within which the sun is entirely hidden from sight . This portion of the shadow is called the See also:

• UMBRA (Lat. for shade or shadow)

umbra . Around the umbra is an enveloping shaded See also:

• CONE (Gr. Kwvos)

cone with its vertices directly towards the sun . To an observer within this region the sun is partly hidden from view . As the apparent path of the moon may pass to the See also:

• NORTH
• NORTH, BARONS
• NORTH, MARIANNE (1830—1890)
• NORTH, ROGER (1653-1734)
• NORTH, SIR THOMAS (1535?-16o1?)

north or See also:

• SOUTH
• SOUTH, ROBERT (1634–1716)

south of the See also:

• LINE

line joining the earth and sun, the See also:

• AXIS (Lat. for " axle ")

axis of its shadow may pass to the north or south of the earth, and not meet' it at all . An eclipse of the sun is called central when the shadow axis strikes any part of the earth; partial when only the See also:

• PENUMBRA (Lat. paene, almost, umbra, a shadow)

penumbra falls upon the earth . It is evident that an eclipse can be seen as central only at those points of the earth's See also:

• SURFACE

surface over which the axis of the shadow passes .

A central eclipse is See also:

• TOTAL

total when the umbra actually reaches the earth; See also:

• ANNULAR, ANNULATE

annular when it does not . These two cases are shown in See also:

• FIGS

figs . 2 and 3 . In the first of these the sun is entirely hidden within the region uu' . In fig . 3 within the region aa' the apparent See also:

• DIAMETER (from the Cr. &a, through, µErpov, measure)

diameter of the sun is slightly greater than that of the moon, and at the moment of greatest eclipse a narrow See also:

• RING (O.E. hring; a word common to Teutonic languages; and probably cognate with the Lat. circus, Gr. KtpKOS or KpLKOS, Skt'. chakra, wheel, circle, cf. also " harangue "); in art, a band of circular shape of varying sizes, made of any material and used f

ring of sunlight is seen surrounding the dark body of the moon . We shall treat the subject in the following sections: I . Phenomena of Eclipses of the Sun and conclusions derived from their observation . II . Eclipses of the Moon . IV . See also:

• CHRONOLOGICAL

Chronological See also:

• LIST (O.E. lisle, a Teutonic word, cf. Dut. lust, Ger. Leiste, adapted in Ital. lista and Fr. lisle)
• LIST, FRIEDRICH (1789-1846)

list of remarkable eclipses of the Sun, past and future, to the end of the loth See also:

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

century .

V . Description of the methods of computing eclipses . I . Phenomena of Eclipses of the Sun . While an eclipse of the sun, whether partial, annular or total, is in progress, no striking phenomena are to be noted until, in the See also:

• CASE
• CASE, JOHN (d. 1600)

case of total eclipses, the moment of the total phase approaches . It will, however, be noticed that as the moon advances on the See also:

• SOLAR, SOLLER (Lat. solarium, Fr.• galetas, Ital. solaio)

solar disk the sharply defined and ragged edge of the moon's disk contrasts strongly with the soft and See also:

• UNIFORM

uniform outline of the sun's See also:

• LIMB

limb . As the total phase approaches, the phenomenon known as shadow bands may sometimes be seen . These consist of seeming vague and rapidly moving See also:

• WAVE

wave-like alternations of See also:

• LIGHT

light and shade flitting over any See also:

• WHITE
• WHITE, ANDREW DICKSON (1832– )
• WHITE, GILBERT (1720–1793)
• WHITE, HENRY KIRKE (1785-1806)
• WHITE, HUGH LAWSON (1773-1840)
• WHITE, JOSEPH BLANCO (1775-1841)
• WHITE, RICHARD GRANT (1822-1885)
• WHITE, ROBERT (1645-1704)
• WHITE, SIR GEORGE STUART (1835– )
• WHITE, SIR THOMAS (1492-1567)
• WHITE, SIR WILLIAM ARTHUR (1824--1891)
• WHITE, SIR WILLIAM HENRY (1845– )
• WHITE, THOMAS (1628-1698)
• WHITE, THOMAS (c. 1550-1624)

white surface illuminated by the sun's rays immediately before and after the total phase . They are probably due to a flickering of the light from the thin See also:

• CRESCENT (Lat. crescens, growing)

crescent, produced by the undulations of the See also:

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

air, in the same way that the twinkling of the stars is produced . The rapid progressive See also:

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

motion sometimes assigned to them may be regarded as the natural result of an See also:

• OPTICAL

optical illusion . A few seconds before the commence- See also:

• PRESENT

present ment of the total phase the red light of the See also:

• CHROMOSPHERE (from Gr. xpwµa, colour, and vqSaipa, a sphere)

chromosphere becomes visible, and will be seen most distinctly as continuations of the solar crescent at its two ends . Owing to the inequalities of the lunar surface, the diminution of the solar crescent does not go on with perfect uniformity, but, just before the last moment, what remains of it is generally broken up into See also:

• SEPARATE

separate portions of light, which, magnified and diffused by the irradiation of the See also:

• TELESCOPE

telescope, L ph enomenon TouCN/NO :LW 3' GLOBE See also:

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

long celebrated under the name of "See also:

• BAILY, EDWARD HODGES (1788-1867)
• BAILY, FRANCIS (1774-1844)
• BAILY, WILLIAM HELLIER (1819-1888)

Baily's beads." These were so called because minutely and TOUCNNeSUNtG Loat vividly described b y See also:

• FRANCIS
• FRANCIS (FRarrcols) OF SALES, ST (1567-1622)
• FRANCIS (Lat. Franciscus, Ital. Francesco, Span. Francisco, Fr. Francois, Ger. Franz)
• FRANCIS, SIR PHILIP (174o-1818)

Francis Baily as he observed them during the annular eclipse of May 15, 1836, when he compared them to a See also:

• STRING

string of See also:

• BRIGHT, JOHN (1811-188g)
• BRIGHT, SIR CHARLES TILSTON

bright beads, irregular in See also:

• SIZE

size and distance from each other .

The disappearance of the last See also:

• BEAD

bead is commonly taken as the beginning of totality . An arc of the chromosphere will then be visible for a few seconds at and on each See also:

• SIDE
• SIDE (mod. Eski Adalia)

side of the point of disappearance, the length and duration of which will depend on the apparent diameter of the moon as compared with that of the sun, being greater in length and longer seen as the excess of diameter of the moon is less . The red prominences may now generally be seen here and there around the whole disk of the moon, while the effulgence of soft light called the See also:

• CORONA (Lat. for " crown ")

corona surrounds it on all sides . Before the invention of the spectroscope, observers of total eclipses could do little more than describe in detail the varying phenomena presented by the prominences and the corona . Drawings of the latter showed it to have the See also:

• APPEARANCE (from Lat. apparere, to appear)

appearance of rays surrounding the dark disk of the moon, quite similar to the See also:

• GLORY (through the O. Fr. glorie, modern gloire, from Lat. gloria, cognate with Gr. KXebs, abets)

glory depicted by the old painters around the See also:

• HEAD (in 0. Eng. heafad; the word is common to Teutonic languages; cf. Dutch hoofd, Ger. Haupt, generally taken to be in origin connected with Lat. caput, Gr. KerbOvi7)
• HEAD, SIR EDMUND WALKER, BART
• HEAD, SIR FRANCIS BOND, BART

head of a See also:

• SAINT (lat. sanctus, " holy ")

saint . The discrepancies between the outlines as thus pictured, not only at different times, but by different observers 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 and See also:

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

place, are such as to show that little reliance can be placed on the details represented by See also:

• HAND
• HAND (a word common to Teutonic languages; cf. Ger. Hand, Goth. handus)
• HAND, FERDINAND GOTTHELF (1786-185r)

hand drawings . During the eclipse of See also:

• JULY

July 8, 1842, the shadow of the moon passed from See also:

• PERPIGNAN

Perpignan, See also:

• FRANCE
• FRANCE, ANATOLE (1844– )

France, through See also:

• MILAN
• MILAN (Ital. Milano, Ger. Mailand, anc. Mediolanum, q.v.)

Milan and See also:

• VIENNA (Ger. Wien; Lat. Vindobona)
• VIENNA, CONGRESS OF (1814-1815)

Vienna, over See also:

• RUSSIA
• RUSSIA (Rossiya)

Russia and Central See also:

• ASIA

Asia, to the Pacific Ocean . Very detailed See also:

• PHYSICAL

physical observations were made, but none which need be specially mentioned in the present connexion . The eclipse of July 28, 185r, was total in Scandinavia and Russia . It was observed in the former region by many astronomers, among them See also:

• SIR

Sir See also:

• GEORGE
• GEORGE, 8TH MARQUESS OF TWEEDDALE (1787-1876)
• GEORGE, HENRY (1839—1897)
• GEORGE, LAKE
• GEORGE, SAINT (d. 303)

George B . See also:

• AIRY, SIR GEORGE BIDDELL (1801-1892)

Airy and W . R .

See also:

• DAWES, HENRY LAURENS (1816-1903)
• DAWES, RICHARD (1708-1766)

Dawes . It was specially noteworthy for the first See also:

• ATTEMPT (Lat. adtemptare, attentare, to try)

attempt to photograph such a phenomenon . A daguerreotype clearly showing the protuberances was taken by Berkowski at the See also:

• OBSERVATORY

Observatory of See also:

• KONIGSBERG (Polish Krolewiec)

Konigsberg . An attempt by G . A . Majocchi to daguerreotype the corona was a failure . Photographs of the eclipse of July 18, 186o, were taken by Padre Angelo See also:

• SECCHI, ANGELO (1818-1878)

Secchi and See also:

• WARREN
• WARREN, GOUVERNEUR KEMBLE (183o-1882)
• WARREN, JOSEPH (1741—1775)
• WARREN, MERCY (1728—1814)
• WARREN, MINTON (1850-1907)
• WARREN, SAMUEL (1807-1877)
• WARREN, SIR JOHN BORLASE, BART
• WARREN, WILLIAM (1812-1888)

Warren De La See also:

• RUE (Fr. rue, Lat. ruta, from Gr. pur)

Rue, which showed the prominences well, and proved that they were progressively obscured by the edge of the advancing moon . It was thus shown that they were solar appendages, and did not belong to the moon, as had sometimes been supposed . The corona was barely visible on De La Rue's plates, but those of Secchi showed it, with its rifts and the bases of the tall coronal wings, to about 15' from the sun's limb . The sketches taken at this eclipse proved that the corona extended in some regions I° from the sun's limb . As the sensitiveness of photographic plates has increased, they have gradually been wholly relied upon for See also:

• INFORMATION (from Lat. informare, to give shape or form to, to represent, describe)

information respecting the corona, so that at the present time naked-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 descriptions are regarded as of little or no scientific value . Owing to the See also:

• GREAT

great contrast between the brilliancy of the coronal light at its See also:

• BASE

base and its increasing faintness as it extends farther from the sun, no one photograph will bring out all the corona .

An exposure of one or two seconds is ample to show the details of inner corona to the best See also:

• ADVANTAGE

advantage, while longer exposures give greater extent of the brighter portions . The most extended streamers are very little brighter than 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, and must be photographed with long exposures . CE) ToocNINC SUN SUN roocmLIG The first application of the spectroscope to the phenomenon was made during the total solar eclipse of See also:

• AUGUST (originally Sextilis)

August 18, 1868, by P . J . C . See also:

• JANSSEN, JOHANNES (1829-1891)
• JANSSEN, or JANSEN (sometimes JOHNSON), CORNELIUS (1593-1664)
• JANSSEN, PIERRE JULES CESAR (1824–1907)

Janssen and other observers in See also:

• INDIA
• INDIA, FRENCH

India . By them was made the See also:

• CAPITAL (i.e. capital stock or fund)
• CAPITAL (Lat. caput, head)

capital See also:

• DISCOVERY

discovery that the red solar prominences give a spectrum of bright lines, and are therefore immense masses of incandescent gases, chiefly See also:

• HYDROGEN [symbol H, atomic weight x-oo8 (0=16)]

hydrogen and the vapours of See also:

• CALCIUM [symbol Ca, atomic weight 40.0 (o= x6)]

calcium and See also:

• HELIUM (from Gr. i)Xcor, the sun)

helium . Janssen also found that this bright-line spectrum could be followed after the eclipse was over, and, in fact, could be observed at any time when the air was sufficiently transparent . By one of those remarkable coincidences which frequently occur in the See also:

• HISTORY

history of See also:

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

science, this last discovery was made independently by Sir See also:

• NORMAN
• NORMAN, SIR HENRY WYLIE (1826-1904)

Norman See also:

• LOCKYER, SIR JOSEPH NORMAN (1836– )

Lockyer in See also:

• ENGLAND
• ENGLAND, THE CHURCH OF

England before the See also:

• NEWS

news of Janssen's success had reached him . It was afterwards found that, by giving great dispersing See also:

• POWER [WILLIAM GRATTAN] TYRONE (1797-1841)

power to the spectroscope, the prominences could be observed in a wide slit, in their true See also:

• FORM (Lat. forma)

form . At this eclipse the spectrum of the corona was also observed, and was supposed to be continuous, while polariscopic observation by See also:

• LIEUTENANT

Lieutenant See also:

• CAMPBELL, ALEXANDER (1788–1866)
• CAMPBELL, BEATRICE STELLA (Mrs PATRICK CAMPBELL) (1865– )
• CAMPBELL, GEORGE (1719–1796)
• CAMPBELL, JOHN
• CAMPBELL, JOHN (1708-1775)
• CAMPBELL, JOHN CAMPBELL, BARON (1779-1861)
• CAMPBELL, JOHN FRANCIS
• CAMPBELL, LEWIS (1830-1908)
• CAMPBELL, REGINALD JOHN (1867— )
• CAMPBELL, THOMAS (1777—1844)

Campbell showed it polarized in planes passing through the sun's centre . The conclusion from these two observations was that the light was composed, at least in great part, of reflected sunlight .

At the total eclipse of August 7, 1869, it was independently found by Professors C . A . See also:

• YOUNG
• YOUNG, A
• YOUNG, ARTHUR (1741-1820)
• YOUNG, BRIGHAM (1801-1877)
• YOUNG, CHARLES MAYNE (1777–1856)
• YOUNG, EDWARD (1683–1765)
• YOUNG, JAMES (1811-1883)
• YOUNG, THOMAS (1773-1829)

Young of See also:

• PRINCETON

Princeton and W . See also:

• HARKNESS, ALBERT (1822—1907)
• HARKNESS, ROBERT (1816—1878)

Harkness of See also:

• WASHINGTON
• WASHINGTON (or WASHINGTON COURT HOUSE)
• WASHINGTON, BOOKER TALIAFERRO (c. 1859– )
• WASHINGTON, BUSHROD (1762-1829)
• WASHINGTON, GEORGE (1732-1799)

Washington that the continuous spectrum of the corona was crossed by a bright line in the See also:

• GREEN, A
• GREEN, ALEXANDER HENRY (1832—1896)
• GREEN, DUFF (1791—1875)
• GREEN, JOHN RICHARD (1837—1883)
• GREEN, MATTHEW (1696-1737)
• GREEN, THOMAS HILL (1836-1882)
• GREEN, VALENTINE (1739–1813)
• GREEN, WILLIAM HENRY (.1825–1900)

green, which was long supposed to be coincident with 1414 of See also:

• KIRCHHOFF, GUSTAV ROBERT (1824-1887)
• KIRCHHOFF, JOHANN WILHELM ADOLF (1826-1908)

Kirchhoff's See also:

• SCALE
• SCALE (1) A

scale . This coincidence is, however, now found not to be real, and the line cannot be identified with that of any terrestrial substance . The name "See also:

• CORONIUM

coronium " has therefore been given to the supposed See also:

• GAS

gas which forms it . It is now known that 1474 is a See also:

• DOUBLE
• DOUBLE (from the Mid. Eng. duble, the form which gives the present pronunciation, through the Old Er. duble, from Lat. duplus, twice as much)

double line, one component of which is produced by See also:

• IRON [symbol Fe, atomic weight 55.85 (0=16)]

iron, while the other is of unknown origin . The wave-length of the See also:

• PRINCIPAL

principal component is 5317, while that of the coronal line was found at the eclipses of 1896 and 1898 to be 5303 . The eclipse of See also:

• DECEMBER (Lat. decent, ten)

December 28, 1870, passed over the south-western corner of See also:

• SPAIN
• SPAIN (Espana)

Spain, See also:

• GIBRALTAR

Gibraltar, See also:

• ORAN (Arabic Wahran, i.e. ravine)

Oran and See also:

• SICILY (Ital. Sicilia)

Sicily . It is memorable for the discovery by Young of the " See also:

• REVERSING

reversing layer " of the solar See also:

• ATMOSPHERE (Gr. fir µ6r, vapour; orkaipa, a sphere)

atmosphere . This See also:

• TERM

term is now applied to a shallow stratum resting immediately upon the photosphere, the absorption of which produces the principal dark lines of the solar spectrum, but which, being incandescent, gives a spectrum of bright lines by its own light when the light of the sun is cut off . This layer is much thinner than the chromosphere, and may be considered to form the base of the latter .

Owing to its thinness, the phenomenon of the reversed bright lines is almost instantaneous in its nature, and can be observed for a See also:

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

period exceeding one or two seconds only near the edge of the shadow-path, where the moon advances but little beyond the solar limb . Near the central line it is little more than a flash, thus giving rise to the term " flash-spectrum." Young also at this eclipse saw bright hydrogen lines when his spectroscope was directed to the centre of the dark disk of the moon . This can only be attributed to the reflection of the light of the prominences and chromosphere from the atmosphere between us and the moon . The coronal light as observed in the spectroscope may thus be regarded as a mixture of true coronal light with chromospheric light reflected from the air, and it is therefore probable that the H and K (calcium) lines of the coronal spectrum are not true coronal lines, but chromospheric . At the eclipse of December 12, 1871, visible in India and See also:

• AUSTRALIA

Australia, Janssen observed, as he supposed, some of the dark lines of the solar spectrum in the continuous spectrum of the corona, especially D, b and G . This would show that an important part of the coronal light is due to reflected See also:

• SUNSHINE

sunshine . This feature of the spectrum, however, is doubtful in the most See also:

• RECENT

recent photographs under the best conditions . At this eclipse the remarkable observation was also made by See also:

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

Colonel See also:

• JOHN
• JOHN (1167–1216)
• JOHN (1290-c. 1320)
• JOHN (1296-1346)
• JOHN (1371–1419)
• JOHN (1468-1532)
• JOHN (1801-1873)
• JOHN (Heb. llni')
• JOHN (ZAPOLYA) (1487-1540)
• JOHN, 4TH MARQUESS OF TWEEDDALE (c. 1695-1762)
• JOHN, DON (1545-1578)
• JOHN, DON (1629–1679)
• JOHN, GOSPEL OF ST
• JOHN, or HAYS (1513–1571)
• JOHN, THE APOSTLE
• JOHN, THE EPISTLES OF

John See also:

• HERSCHEL, CAROLINE LUCRETIA (1750-1848)
• HERSCHEL, SIR F
• HERSCHEL, SIR FREDERICK WILLIAM (1738-1822)
• HERSCHEL, SIR JOHN FREDERICK WILLIAM, BART

Herschel and Colonel J . F . See also:

• TENNANT, CHARLES (1768-1838)
• TENNANT, SMITHSON (1761-1815)
• TENNANT, WILLIAM (1784-1848)

Tennant that the characteristic line cf the coronal spectrum is as bright in the dark rifts of the corona as elsewhere . This would show that the gas coronium does not form the streamers of the corona, but is spherical in form and distributed uniformly about the sun . Photographs were alsotaken on wet plates by a party in See also:

• JAVA

Java and by the parties of See also:

• LORD
• LORD (O. Eng. hldford, i.e. hldfweard, the warder or keeper of bread, hlIf, loaf; the word is not represented in any other Teutonic language)
• LORD, JOHN (1810-1894)

Lord See also:

• LINDSAY

Lindsay (at Baikul, India) and of Colonel Tennant (at Dodabetta) .

The Baikul and Dodabetta photographs were of small size (moon's diameter= 136 in.), but of excellent See also:

• DEFINITION (Lat. definitio, from de-finire, to set limits to, describe)

definition . A searching study was made of them by A . C . Ranyard and W . H . See also:

• WESLEY (FAMILY)
• WESLEY, JOHN (1703-1791)
• WESLEY, SAMUEL (1766-1837)
• WESLEY, SAMUEL SEBASTIAN (1810–1876)

Wesley (See also:

• MEMOIRS

Memoirs R.A.S. vol. xli., 1879), and for the first time a satisfactory See also:

• REPRESENTATION

representation of the co-on a was obtained . The drawings in the See also:

• VOLUME

volume quoted show its polar rays, wings, interlacing filaments and rifts as they are now known to be, as well as the forms and details of the prominences . The eclipse of See also:

• APRIL

April 16, 1874, was observed in South See also:

• AFRICA
• AFRICA, ROMAN

Africa by E . J . See also:

• STONE
• STONE (0. Eng. shin; the word is common to Teutonic languages, cf. Ger. Stein, Du. steen, Dan. and Swed. sten; the root is also seen in Gr. aria, pebble)
• STONE, CHARLES POMEROY (1824-1887)
• STONE, EDWARD JAMES (1831-1897)
• STONE, FRANK (1800-1859)
• STONE, GEORGE (1708—1764)
• STONE, LUCY [BLACKWELL] (1818-1893)
• STONE, MARCUS (184o— )
• STONE, NICHOLAS (1586-1647)

Stone, H.M. astronomer at the Cape, who traced the coronal line about 30' (430,000 m.) from the sun's limb . The visual corona was seen to extend in places some 90' from the limb . The eclipse of April 6, 1875, was observed in See also:

• SIAM (known to its inhabitants as Muang Thai)

Siam by Sir J .

Norman Lockyer and See also:

• PROFESSOR (the Latin noun formed from the verb profiteri, to declare publicly, to acknowledge, profess)

Professor See also:

• ARTHUR (Fr. Arius)
• ARTHUR, CHESTER ALAN (1830 – 1886)

Arthur Schuster . Their photographs showed the calcium and hydrogen lines in the prominence spectrum . The eclipse of July 29, 1878, was observed by many astronomers in the See also:

• UNITED

United States along a line extending from See also:

• WYOMING

Wyoming to See also:

• TEXAS

Texas . A number of the stations were at high altitudes (up to 14,000 ft.), and the sky was generally very clear . The visible corona extended on both sides of the sun along the See also:

• ECLIPTIC

ecliptic for immense distances—at least twelve lunar diameters, about eleven million See also:

• MILES, NELSON APPLETON (1839— )

miles . Photographs taken by the parties of Professors A . See also:

• HALL
• HALL (generally known as SCHWABISCH-HALL, tc distinguish it from the small town of Hall in Tirol and Bad-Hall, a health resort in Upper Austria)
• HALL (O.E. heall, a common Teutonic word, cf. Ger. Halle)
• HALL, BASIL (1788-1844)
• HALL, CARL CHRISTIAN (1812–1888)
• HALL, CHARLES FRANCIS (1821-1871)
• HALL, CHRISTOPHER NEWMAN (1816—19oz)
• HALL, EDWARD (c. 1498-1547)
• HALL, FITZEDWARD (1825-1901)
• HALL, ISAAC HOLLISTER (1837-1896)
• HALL, JAMES (1793–1868)
• HALL, JAMES (1811–1898)
• HALL, JOSEPH (1574-1656)
• HALL, MARSHALL (1790-1857)
• HALL, ROBERT (1764-1831)
• HALL, SAMUEL CARTER (5800-5889)
• HALL, SIR JAMES (1761-1832)
• HALL, WILLIAM EDWARD (1835-1894)

Hall and W . Harkness gave the details of the inner corona and of the polar rays, showing the filamentous See also:

• CHARACTER (Gr. xapareri7p, from xap&crew, to scratch)

character of the corona, especially at its base in the polar regions . A photograph taken by the party of Professor E . S . See also:

• HOLDEN, HUBERT ASHTON (1822-1896)
• HOLDEN, SIR ISAAC, BART

Holden showed the See also:

• OUTER

outer corona to a distance of 5o' from the moon's limb . The bright-line spectrum of the corona was excessively faint and, as the solar activity (measured by sun-spot frequency) was near a minimum, it was concluded that the brilliancy of the coronium line varied in the sun-spot period, a conclusion which subsequent eclipse observations seem to have verified .

It is not yet certain that the other coronal spectrum lines vary in the same way . The eclipse of May 17, 1882, was observed in See also:

• EGYPT

Egypt . On the photographs of the corona the See also:

• IMAGE (Lat. imago, perhaps from the same root as imitari, copy, imitate)

image of a bright See also:

• COMET (Gr. Koµieiis, long-haired)

comet was found, the first instance of the sort . (A faint comet was found on the plates of the Lick Observatory eclipse expedition to See also:

• CHILE, or CHILI (derived, it is said, from the Quichua chin , cold, or tchili, snow)

Chile in 1893.) The slitless spectroscope showed the green line (coronium) and D3 (helium) in the coronai spectrum . The eclipse of May 6, 1883, was observed from a small See also:

• CORAL

coral See also:

• ATOLL (native name atollon in the Maldive Islands)

atoll in the South Pacific Ocean by parties from See also:

• AMERICA

America, England, France, See also:

• AUSTRIA
• AUSTRIA, LOWER (Ger. Niederosterreich or Osterreich unter der Enns, " Austria below the river Enns ")
• AUSTRIA, UPPER (Ger. Oberosterreich or Osterreich ob der Enns, " Austria above the river Enns ")

Austria and See also:

• ITALY
• ITALY (Italia)

Italy . A thorough See also:

• SEARCH, or VISIT AND SEARCH

search was made by Holden (with a 6 in. telescope) for an See also:

• INTRA

intra-See also:

• MERCURIAL

Mercurial planet, without success, during an unusually long totality (5 m . 23 s.) . J . Palisa also searched for such a planet . Janssen again reported the presence of dark lines in the coronal spectrum . " White " prominences were seen by P . Tacchini .

The eclipse of August 29, ,886, was observed in the See also:

• WEST
• WEST, BENJAMIN (1738-1820)
• WEST, NICHOLAS (1461-1533)

West Indies . The See also:

• ENGLISH

English photographs of the corona, taken with a slitless spectroscope, show the hydrogen lines as well as K and f . Tacchini devoted his See also:

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

attention to the spectra of the prominences, and showed that their upper portions contained no hydrogen lines, but only the H and K lines of calcium . He alse observed a very extensive " white " prominence . It was shown on the photo-graphs of the corona, but could not be seen in the Ha line with the spectroscope . It has been suggested by Professor G . E . See also:

• HALE, EDWARD EVERETT (1822-1909)
• HALE, HORATIO (1817–1896)
• HALE, JOHN PARKER (1806–1873)
• HALE, NATHAN (1756-1776)
• HALE, SIR MATTHEW (1609-1676)
• HALE, WILLIAM GARDNER (1849- )

Hale that the See also:

• COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

colour of a "white" prominence may be due to the fact that the H and K lines (calcium) are of their normal intensity, while the less refrangible prominence lines are, from some unknown cause, comparatively faint . It is known that the intensity of such lines does, in fact, vary, though it is not yet certain that the "white" prominences are produced in this way . The subject is one demanding further observation . High prominences are generally " white " at their summits, " red " at their bases . The Harvard See also:

• COLLEGE (Collegium)

College Observatory photographs show the corona out to 9o' from the moon's limb, though no detail is visible beyond 6o' .

W . H . See also:

• PICKERING
• PICKERING, EDWARD CHARLES (1846- )
• PICKERING, TIMOTHY (174 1829)

Pickering made a See also:

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

series of photographic photometric See also:

• MEASURES

measures of the corona, some of which are given 890 below, together with results deduced by Holden from the eclipses of See also:

• JANUARY

January and December 1889: August January December 1886 . 1889 . 1889 . See also:

• INTRINSIC (through Fr. intrinsique, from Lat. intrinsecus, inwardly; inter, within, secus, following, from root of sequi, to follow)

Intrinsic actinic brilliancy of the 0.031 0.079 0.029 brightest parts of the corona . Do. of the polar rays . . . . . 0.053. o•oi6 Do. of the sky near the sun 0.0007 0.0050 0.0009 Ratio of intrinsic brilliancy of the 44 to I 16 to I 32 to I brightest parts of the corona to that of the sky (actinic) . Magnitude of the faintest See also:

• STAR

star 2.3 shown on the eclipse negatives The results in the first and third columns are derived from plates taken in a very humid See also:

• CLIMATE

climate, and are not very different . The eclipse of August 19, 1887, was total in See also:

• JAPAN

Japan and Russia, but cloudy See also:

• WEATHER (O. Eng. weder; the word is common to Teutonic languages; cf. Du. weder, Dan. veir, Icel. ve8r, and Ger. Wetter and Gewitter, storm; the root is wa- to blow, from which is derived " wind ")

weather prevented successful observations except in See also:

• SIBERIA

Siberia and eastern Russia .

The eclipse of January 1, 1889, was observed in See also:

• CALIFORNIA
• CALIFORNIA, LOWER (Baja California)
• CALIFORNIA, UNIVERSITY OF

California and See also:

• NEVADA
• NEVADA (a Spanish word meaning " snow-clad " or " snowy land," originally applied to a snow-capped mountain range on the Pacific slope)

Nevada by many See also:

• AMERICAN

American astronomers . The photographs of the corona, especially those by Charoppin and E . E . See also:

• BARNARD, FREDERICK AUGUSTUS PORTER (1809–1889)
• BARNARD, GEORGE GREY (1863— )
• BARNARD, HENRY (1811-1900)
• BARNARD, JOHN
• BARNARD, LADY ANNE (1750–1825)

Barnard, show a See also:

• WEALTH

wealth of detail . Those of Barnard, of the Lick Observatory party, were studied by Holden, and exhibited the fact that rays, like the " polar-rays," extended all See also:

• ROUND (O. Fr. rond, Lat. rotundus, the Fr. is the source also of Du. rond; Ger., Swed., Dan. and Nor. rond)

round the sun, instead of. being confined to the polar regions only . The outer corona was registered out to See also:

• LOO (formerly called " Lanterloo," Fr. lanturlu, the refrain of a popular 17th-century song)

loo' from the moon's limb on Charoppin's negatives, to 130' on those of Lowden and See also:

• IRELAND
• IRELAND, CHURCH
• IRELAND, CHURCH OF
• IRELAND, JOHN (1761-1842)
• IRELAND, JOHN (1838- )
• IRELAND, WILLIAM HENRY (1777-1835)

Ireland . On other plates the outline of the moon is visible projected on the corona before totality began . The spectrum of the corona showed few bright lines besides those of coronium and hydrogen . The eclipse of December 22, 1889, was observed in See also:

• CAYENNE

Cayenne, S . America, by a party from the Lick Observatory under rather unfavourable conditions . Expeditions sent to Africa were baffied by cloudy weather . See also:

• FATHER

Father See also:

• STEPHEN
• STEPHEN (1097?-1154)
• STEPHEN (ISTVAN) BATHORY (1533-1586)
• STEPHEN, SIR JAMES (1789-1859)
• STEPHEN, SIR JAMES FITZJAMES, BART
• STEPHEN, SIR LESLIE (1832-1904)

Stephen See also:

• JOSEPH
• JOSEPH, COMTE DE (1785-1870)
• JOSEPH, FATHER (FRANCOIS LECLERC DU TREMBLAY) (1577-1638)

Joseph See also:

• PERRY
• PERRY (from Fr. Moire, from poire, a pear)
• PERRY, MATTHEW CALBRAITH (1794–1858)
• PERRY, OLIVER HAZARD (1785-1819)

Perry observed at .

Salute Islands, See also:

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

French See also:

• GUIANA (Guyana, Guayana')

Guiana, and obtained some photographs of value . The effort cost him his See also:

• LIFE

life, for he died of malarial See also:

• FEVER (Lat. febris, connected with fervere, to burn)

fever five days after the eclipse . The •eclipse of April 16, 1893, was observed by See also:

• BRITISH

British and French parties in Africa and See also:

• BRAZIL
• BRAZIL, or BRASIL

Brazil, and by Professor J . M . Schaeberle of the Lick Observatory in Chile . The Chile photo-. graphs of the corona were taken with a See also:

• LENS
• LENS (from Lat. lens, lentil, on account of the similarity of the form of a lens to that of a lentil seed)

lens of 40 f t. See also:

• FOCUS (Latin for " hearth " or " fireplace ")

focus, and are extremely See also:

• FINE

fine . They show a faint comet near the sun . No great extensions to the corona were shown on any of the negatives, or seen visually, though they were specially looked for by British parties . The neighbourhood of the sun was carefully examined by G . Bigourdan without finding any planet . The spectrum of the corona was the usual one . The following lines were photo-graphed in slitless spectroscopes, and undoubtedly belong to the corona: W .

L . 3987; 4086; 4217; 4231; 4240; 4280; 4486; 5303 (the last number is the wave-length of the green coronium line) . All of these have been seen in slit spectroscopes also . It is possible that two lines observed by Young in 1869, namely, W . L . (See also:

• ANGSTROM, ANDERS JONAS (1814-1874)

Angstrom) 5450 and 5570, should be added to the list of undoubted coronal lines . It is not likely that helium or hydrogen or calcium vapour forms part of the corona . The wave-lengths of some 700 lines belonging to the chromosphere and prominences were determined by the British parties . The eclipse of August 9, 1896, was total in See also:

• NORWAY
• NORWAY (Norge)

Norway, Novaya Zemlya and Japan . The See also:

• DAY (O. Eng. dreg, Ger. Tag; according to the New English Dictionary, " in no way related to the Lat. dies")
• DAY, JOHN (1574-1640?)
• DAY, THOMAS (1748-1789)

day was very unfavourable as to weather, but See also:

• GOOD, JOHN MASON (1764-1827)

good photographs of the corona were obtained by See also:

• RUSSIAN

Russian parties in Siberia and See also:

• LAPLAND, or LAPPLAND

Lapland . Shackelton, in Novaya Zemlya, with a prismatic See also:

• CAMERA (a Latin adaptation of Gr. Kagapa, an arched chamber)

camera obtained a photograph of the reversing-layer at the beginning of totality . This photograph completely confirms Young's discovery, and shows the prominent See also:

• FRAUNHOFER, JOSEPH VON (1787-1826)

Fraunhofer lines bright, the bright lines of the chromosphere spectrum being especially conspicuous .

At the solar eclipse of January 22, 1898, the shadow of the moon traversed India from the western See also:

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

coast to the See also:

• HIMALAYA

Himalaya . The duration of totality was about 2 M . The eclipse was very fully observed, more than too negatives of the corona being secured . The See also:

• EQUATORIAL

equatorial See also:

• EXTENSION (Lat. ex, out ; tendere, to stretch)

extension of the visible corona was See also:

• SHORT, FRANCIS JOB (1857– )

short and faint, and the invisible (spectroscopic) corona was also veryfaint . The spectrum of the reversing-layer was successfully photographed; one set of negatives shows the polarization of one of the longest streamers of the corona, and proves the presence of dust particles reflecting solar light . The bright-line spectrum of hydrogen in the chromosphere was followed to the thirtieth point of the series, and the wave-lengths were shown to agree closely with Balmer's See also:

• FORMULA
• FORMULA (Lat. diminutive of forma, shape, pattern, &c., especially used of rules of judicial procedure)

formula (see See also:

• SPECTROSCOPY (from Lat. spectrum, an appearance, and Gr. a-sore y, to see)

SPECTROSCOPY) . The wave-length of coronium was found to be 5303 (not 5317 as previously supposed), and the brightness of the corona was measured . E . W . Maunder made the curious observation of coronal See also:

• MATTER

matter enveloping a prominence in the form of a See also:

• HOOD,
• HOOD, JOHN BELL (1831–1879)
• HOOD, SAMUEL HOOD, VISCOUNT (1724–1816)
• HOOD, SIR SAMUEL (1762-1814)
• HOOD, THOMAS (1799-1845)
• HOOD, TOM (1835–1874)

hood . Observations of the eclipse of May 28, 1900, were favoured in a remarkable degree by the See also:

• ABSENCE (Lat. absentia)

absence of clouds . The photographs of the corona obtained by W .

W . Campbell extended four diameters of the sun on the west side . The sun's edge was photographed with an See also:

• OBJECTIVE, or OBJECT GLASS

objective-See also:

• PRISM (Gr. rrpivµa, properly a thing sawn, Irpii"ety, to saw)

prism spectrograph composed of two 60° prisms in front of a telescope of 2 in. See also:

• APERTURE (from Lat. aperire, to open)

aperture and 6o in. focus . A fine photograph, 6 in. long, of the bright- and dark-line spectra of the sun's edge at the end of totality was thus obtained . It shows 600 bright lines sharply in focus besides the dark-line spectrum, to which the bright lines gave way as the sun re-appeared . The coronal material radiating the green light was found to be markedly heaped up in the sun-spot regions . No dark lines were found in the spectrum of the inner corona . G . E . Hale and E . B . See also:

• FROST (a common Teutonic word, cf. Dutch, vorst, Ger. Frost, from the common Teutonic verb meaning " to freeze," Dutch, vriezcn, Ger. frieren; the Indo-European root is seen in Lat. pruina, hoar-frost, cf. prurire, to itch, burn, pruna, burning coal, Sans
• FROST, WILLIAM EDWARD (1810–1877)

Frost also photographed the combined bright.-and dark-line spectra of the solar cusps at the instants before and after totality .

On one photograph showing no dark lines 70 bright lines could be measured between 4070 and 4340 . On another were 70 bright lines between Hb and Hs . On a third were 266 bright lines between 4026 and 4381, and some dark lines . These lines show a marked dissimilarity from the solar spectrum .. (S . N.) The eclipse of May i8, See also:

• LOOT

loot, was observable in See also:

• MAURITIUS

Mauritius with 32 minutes of totality, and in See also:

• SUMATRA

Sumatra with 62 minutes . Unfortunately there was cloudy weather in Sumatra, which at some stations prevented observations entirely and at others neutralized the advantages promised by the long duration of totality . Thus spectroscopic observations for the detection of motion of the corona, for which the long totality gave a See also:

• SPECIAL

special opportunity, failed owing to 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; and the search for intra-Mercurial planets had only a negative result, though stars down to magnitude 8.8 were photographed on the plates . But though no particular step in advance was taken, successful records of the eclipse were obtained, which will enable comparison to be made with other eclipses and will contribute their See also:

• SHARE (O. Eng. scearu, chiefly in compounds, e.g. land-scearu, a share of land, from sceran to cut; cf. " shear" )

share to the discussion of the whole series . These include photographs of the corona, showing that it was of the sun-spot minimum type, and available for' measures of its brightness; photographs of the spectra of the chromosphere and corona which are of the same See also:

• GENERAL
• GENERAL (Lat. generalis, of or relating to a genus, kind or class)

general character as those obtained at previous eclipses; photographs showing the polarization of the corona, available for quantitative measures of polarization at different points . Photographs of the spectrum of the outer corona taken by the Lick Observatory party show a strong Fraunhofer dark-line spectrum, consistent with the view that the light is reflected sunlight . At Mauritius there was no cloud, but the definition was poor .

Successful photographs of the corona were obtained for comparison with those taken in Sumatra one and a See also:

• HALF

half See also:

• HOURS, CANONICAL

hours later, but nothing of great See also:

• INTEREST

interest was revealed by the comparison . The eclipse of August 30, 1905, offered a duration of 31 minutes in Spain, the track See also:

• RUNNING

running from Labrador through Spain to North Africa, and affording excellent opportunities for observers: who flocked to the central line in great See also:

• NUMBERS, BOOK OF
• NUMBERS, PARTITION OF

numbers . Unfortunately it was cloudy in Labrador, so that the special advantages of the long line of possible stations were lost . Exceptionally good weather conditions were enjoyed in See also:

• ALGERIA
• ALGERIA (Algerie)

Algeria and See also:

• TUNISIA (Regency of Tunis)

Tunisia, and full advantage was taken of them by H . F . Newall, C . Trepied and others at Guelma, by the party from See also:

• GREENWICH

Greenwich and G . Bigourdan at See also:

• SFAX (Arabic Asfakis or Safakus, the cucumbers)

Sfax . That G . Newall's spectroscopic photographs for rotation of the corona again gave no result is a clear indication of the. faintness of the corona at 3' from the limb; but F . W . Dyson at Sfax obtained two new lines at 5536 and 5117 in the spectrum of the corona; and a very large number of photographs of the corona (including many in polarized light on several different plans), of its spectrum, and of the spectrum of the chromosphere, were obtained by the various parties, which will afford copious material for discussion .

Newall also obtained a polarized spectrum of the corona . Altogether no less than eighty stations were occupied . There were English, American, Russian and See also:

• GERMAN
• GERMAN, DUTCH AND SCANDINAVIAN

German observers in Egypt; English and French in Algeria and Tunisia; English in See also:

• MAJORCA (Mallorca)

Majorca; observers of almost all nationalities in Spain; and English and American in Labrador . In Egypt the weather was bright, though the sun was See also:

• LOW, SETH (1850- )
• LOW, WILL HICOK (1853- )

low; in Majorca and Spain there were See also:

• LOCAL

local clouds . Consequently many observations, in addition to those in Labrador, were lost, notably the special spectroscopic observations undertaken by Evershed on the See also:

• NORTHERN

northern limit of totality, and the observations of See also:

• RADIATION, THEORY OF

radiation undertaken by H . L . Callendar . A search for intra-Mercurial planets was conducted on an elaborate See also:

• PLAN
• PLAN (from Lat. planes, flat)

plan, with similar batteries of telescopes, in Egypt, Spain and Labrador, by three parties from the Lick Observatory, but the examination of the plates showed nothing noteworthy . Pending discussion of the greater part of the material, some interesting preliminary results were published in r906 by the French observers . C . E . H .

See also:

• BOURGET, PAUL CHARLES JOSEPH (1852– )

Bourget and Montangerand conclude that there is a marked See also:

• DIVISION (from Lat. dividere, to break up into parts, separate)

division of the chromosphere into two regions or shells, a See also:

• LOWER

lower or "reversing-layer," extending only 1" from the limb, and a chromospheric layer extending to 3" or 4"; and that the coronal light contains less See also:

• BLUE (common in different forms to most European languages)

blue and See also:

• VIOLET

violet, but more green and yellow, than sunlight; while Fabry, by visual methods, obtained measures of the total and intrinsic intensity of the light from the corona dosely See also:

• CON

con-firming recent photographic observations, finding the total brightness about equal to that of the full moon, and the intrinsic brightness at 5' from the limb about one See also:

• QUARTER (through Fr. from Lat. quartarius, fourth part)

quarter of that of the full moon . (H . H . T.) II . Eclipses of the Moon . The physical phenomena attending eclipses of the moon are no longer of a high See also:

• ORDER
• ORDER (through Fr. ordre, for earlier ordene, from Lat. ordo, ordinis, rank, service, arrangement; the ultimate source is generally taken to be the root seen in Lat. oriri, rise, arise, begin; cf. " origin ")
• ORDER, HOLY

order of interest either to the layman or scientific observer . A brief statement of them and their causes will there-fore be sufficient . An observer watching such an eclipse from the moon would see the earth, which has nearly four times the apparent diameter of the sun, impinging on the sun's disk and slowly hiding it . The phenomenon would be quite similar to that of an eclipse of the sun seen from the earth, until the sun was completely covered . During the progress of this partial eclipse the moon would be passing into the earth's penumbra . As the moment of total obscuration approached, a red See also:

• BAND

band of light would rapidly form in the neighbourhood of the disappearing limb of the sun, and gradually extend around the earth . This would arise from the See also:

• REFRACTION
• REFRACTION (Lat. refringere, to break open or apart)

refraction of the sun's light by the earth's atmosphere, and the absorption of its blue rays .

When the light of the sun was completely hidden, a reddish ring of great brilliancy would, owing to this cause, surround the entire dark body of the earth during the period of the total eclipse . The aspect of the moon, as seen from the earth, corresponds to this view from the moon . The fading of the moon's light, due to its entrance into the penumbra, is scarcely noticeable without See also:

• DIRECT

direct photometric determination until near the beginning of the total phase . Then, as the limb of the moon approaches the earth's shadow, it begins to darken . When only a small portion has entered into the shadow, that portion is completely hidden . But, as the total phase approaches, the part of the moon's disk immersed in the penumbra becomes visible by a reddish coppery light—that of the sun refracted through the lower parts of the earth's atmosphere . The brightness of this See also:

• ILLUMINATION

illumination is different in different eclipses, a circumstance which may be attributed to the greater or less degree of cloudiness in those regions of the earth's atmosphere through which the light of the sun passes in order to reach the moon . Its colour is due to absorption in passing through the earth's atmosphere . It has been known since remote antiquity that eclipses occur891 in cycles . These cycles are known now to be determined principally by the motion of the moon's See also:

• NODE (Lat. nodus, a loop)

node and the relations between the revolutions of the earth round the sun and the moon round the earth . Owing to the inclination of the moon's See also:

• ORBIT (from Lat. orbita, a track, orbis, a wheel)

orbit to the See also:

• PLANE

plane of the ecliptic, an eclipse of the sun can occur only when the con-junction of the sun and moon takes place within about 16° of one of the nodes of the moon's orbit . The See also:

• SEA (in O. Eng. sae, a common Teutonic word; cf. Ger. See, Dutch Zee, &c.; the ultimate source is uncertain)
• SEA, COMMAND OF THE

sea oes. eclipse can be total only within about 11° of the node .

An eclipse of the moon can occur only when the line sun-moanearth makes an See also:

• ANGLE (from the Lat. angulus, a corner, a diminutive, of which the primitive form, angus, does not occur in Latin; cognate are the Lat. angere, to compress into a bend or to strangle, and the Gr. ayKOS, a bend; both connected with the Aryan root ank-, to

angle less than about rr° with the line of nodes; and the eclipse can be total only within about 8° of the node; the See also:

• AVERAGE

average limiting distances varying 1° or 2° according to the circumstances . These conditions being understood, the cycles of recurrence of eclipses of either See also:

• KIND (O. E. ge-cynde, from the same root as is seen in " kin," supra)

kind can be worked out geometrically from the mean motions of the sun, moon, node and See also:

• PERIGEE (Gr. zrepi, near, 'A', the earth)

perigee by the aid of geometric conceptions shown in their simplest form in fig . 4 . Here E is the earth, at the centre of a circle representing the mean orbit of the moon around it . MN is the line of nodes which is moving in the See also:

• RETROGRADE (from the Lat. retro, backwards, gradiri, to go)

retrograde direction from N towards S1, at a See also:

• RATE

rate of about 19.3° in a See also:

• YEAR

year, making a complete revolution in 18.6 years . Let the sun at the moment of some new moon be in the line ES1, continued . If the angle NES1 is less than 16° there will FIG . 4. probably be an eclipse of the sun, which may be central if the angle is less than 1r° . Let the next new moon take place in the line ES2 a See also:

• MONTH
• MONTH (a common Teutonic word, cf. Ger. Mond, Du. maand, Dan. maaned, &c., and cognate with Lat. mensis, Gr. µi7v, &c., in other branches of the Indo-Germanic family; all ultimately from the root seen in the word for the moon in nearly all those languages

month later . The mean value of the angle S1ES2 is about 29°; but as the node N has moved towards S1 about 1.4° during the See also:

• INTERVAL

interval, the sum of the angles NES1 and NES2 will be somewhat greater than S1ES2 by about 1.6° . The result is that if these two angles are nearly equal there may be two small partial eclipses of the sun, after which no more can occur until, by the See also:

• ANNUAL

annual revolution of the earth, the direction of the sun approaches the opposite Iine of nodes EM, nearly six months later . The result is that there are in the course of any one year two " eclipse seasons " each of about one month in duration, in which at least one eclipse of the sun, or possibly two small partial eclipses, may occur .

One eclipse of the moon will generally, but not always, occur during a See also:

• SEASON (0. Fr. seson, seison, mod. saison, Lat. satio, sowing time, the spring, from serere, to sow; in Late Lat. the word is found with its present meaning, the spring being considered as particularly the season of the year)

season . Owing to the retrograde motion of the node the direction ES of the sun returns to the node at the end of about 347 days, so that a third eclipse season may commence before the end of ,a year . In this way there is a possible but very rare maximum of five eclipses of the sun in a year . Owing to the motion of the line of nodes each eclipse season occurs about 19 days earlier in the year than it did the year before . Another conclusion from the greater eclipse limit for the sun than for the moon is that in the long run eclipses of the sun, as regards the earth generally, occur oftener than those of the moon . But as any eclipse of the sun is visible only from a limited region of the earth's surface, while one of the moon may be seen from an entire hemisphere, more eclipses of the moon are visible at any one place than of the sun . If, starting with a See also:

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

conjunction along some line ES1, we See also:

• MARK
• MARK, CARL (1858– )
• MARK, GOSPEL OF ST
• MARK, ST

mark by radial lines from E the successive conjunctions year after year, we shall find that at the end of 18 years and about 11 days the 223rd conjunction will fall once more very near the line ES1, the angle NES1 being"about 24' greater than before . Successive eclipses will then occur very nearly in the same order as they did 18 years and 11 days before . This period of recurrence has been known from remote antiquity and is called the See also:

• SAROS

Saros . What is most remarkable in this period is that in addition to the distance from the node being nearly the same as before, the See also:

• LONGITUDE (from Lat. longitudo, " length ")

longitude of the sun increases by only 11° and the distance of the moon from its perigee has changed less than 3° . The result of this approach to coincidence is that the recurring eclipse will generally be of the same kind—total, annular or partial—through a number of successive periods . To see the See also:

• LAW
• LAW (0. Eng. lagu, M. Eng. lawe; from an old Teutonic root lag, " lie," what lies fixed or evenly; cf. Lat. lex, Fr. loi)