See also:

• ASTROLABE (from Gr. liar pop, star, and Aa(3eiv, to take)

ASTROLABE (from Gr. liar pop, See also:

• STAR

star, and Aa(3eiv, to take)  , an See also:

• INSTRUMENT (Lat. instrumentum, from insincere, to build up, furnish, arrange, prepare)

instrument used not only for stellar, but for See also:

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

solar and lunar See also:

• ALTITUDE (Lat. altitudo, from altus, high)

altitude-taking . The principle of the See also:

• ASTROLABE (from Gr. liar pop, star, and Aa(3eiv, to take)

astrolabe is explained in fig . 2 . There were two kinds,—spherical and planispheric . P in the See also:

• PLANE

plane of the circle, the 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 B 0 D will be the angle sub-tended by the two See also:

• OBJECTS

objects P and Q at 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 . The earliest forms were " armillae " and spherical . Gradually, from Eratosthenes to Tycho, See also:

• HIPPARCHUS (fl. 146-126 B.c.)

Hipparchus playing the most important See also:

• PART

part among See also:

• ANCIENT
• ANCIENT (also spelt ANTIENT; derived, through the Fr. ancien, old, from the late Lat. antianum, from ante, before)

ancient astronomers, the complex astrolabe was evolved, large specimens being among the See also:

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

chief observa- -See also:

• ASTROLOGY

ASTROLOGY 795 tory See also:

• INSTRUMENTS

instruments of the 15th, 16th and even r 7th centuries; while small ones were in use among travellers and learned men, not only for astronomical, but for astrological and topographical purposes . Nearly every one of the modem instruments used for the observations of See also:

• PHYSICAL

physical See also:

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

astronomy is a part of the perfected astrolabe . A collection of circles such as is the armillary See also:

• SPHERE (Gr. vclsa?pa, a ball or globe)

sphere, if each circle were fitted with a view-See also:

• TUBE (Lat. tuba)

tube, might be considered a See also:

• COMPLETE

complete astrolabe . Tycho's armillae were astrolabes . In fact the See also:

• MODERN

modern See also:

• EQUATORIAL

equatorial, and the altitude and See also:

• AZIMUTH (from the Arabic)

azimuth circle are astrolabes in the strictest and See also:

• OLDEST

oldest meaning of the See also:

• TERM

term; and Tycho in one of his astrolabes came so near the modern equatorial that it may be taken as the first of the See also:

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

kind . The two forms of the planispheric astrolabe most widely known and used in the r5th, 16th and even 17th centuries were: (r) the portable astrolabe shown in fig .

1 (See also:

• PLATE

Plate) . This originated in the See also:

• EAST
• EAST, ALFRED (1849- )

East, and was in See also:

• EARLY
• EARLY, JUBAL ANDERSON (1816-1894)

early use in See also:

• INDIA
• INDIA, FRENCH

India, See also:

• PERSIA

Persia and See also:

• ARABIA

Arabia, and was introduced into See also:

• EUROPE

Europe by the See also:

• ARABS

Arabs, who had perfected it —perhaps as early as A.D . 700 . It combines the planisphere and armillae of Hipparchus and others, and the See also:

• THEODOLITE

theodolite of See also:

• THEON
• THEON, AELIUS

Theon, and was usually of See also:

• BRASS
• BRASS (O. Eng. braes)

brass, varying in See also:

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

diameter from a couple of inches to a See also:

• FOOT

foot or more . It was used for taking the altitudes of See also:

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

sun, 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 and stars; for calculating See also:

• LATITUDE (Lat. latitudo, latus, broad)

latitude; for determining the points of the See also:

• COMPASS (Fr. corn pas, ultimately from Lat. cum, with, and passus, step)

compass, and 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; for ascertaining heights of mountains, &c.; and for construction of horo- scopes . The instrument was a marvel of convenience and ingenuity, and was called " the mathematical See also:

• JEWEL, JOHN (1522-1571)

jewel." Nevertheless it passed out of use, because incapable of any See also:

• GREAT

great precision . (2) The mariner's astrolabe, fig . 3, was adapted from that of astronomers by See also:

• MARTIN (Martinus)
• MARTIN, BON LOUIS HENRI (1810-1883)
• MARTIN, CLAUD (1735-1800)
• MARTIN, FRANCOIS XAVIER (1762-1846)
• MARTIN, HOMER DODGE (1836-1897)
• MARTIN, JOHN (1789-1854)
• MARTIN, LUTHER (1748-1826)
• MARTIN, SIR THEODORE (1816-1909)
• MARTIN, SIR WILLIAM FANSHAWE (1801–1895)
• MARTIN, ST (c. 316-400)
• MARTIN, WILLIAM (1767-1810)

Martin See also:

• BEHAIM (or BE1?EM), MARTIN (1436?-1507)

Behaim, c . 1480 . This was the instrument used by See also:

• COLUMBUS
• COLUMBUS, CHRISTOPHER [in Spanish CRISTOBAL COLON] (c. 1446, or perhaps rather 1451, -15o6)

Columbus . With the tables of the sun's See also:

• DECLINATION (from Lat. declinare, to decline)

declination then available, he could calculate his latitude by See also:

• MERIDIAN
• MERIDIAN (from the Lat. meridianus, pertaining to the south or mid-day)

meridian altitudes of the sun taken with his astrolabe . The mariner's astrolabe was superseded by 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:

• HADLEY
• HADLEY, ARTHUR TWINING (1856– )
• HADLEY, JAMES (1821–1872)

Hadley's quadrant of 1731 .