GLOBE, a sphere, a round solid body, generated by the revolution of a semi-circle about its diameter. Globe, or artificial globe, in geography and astronomy, is more particularly used of a sphere made of metal, plaster or pasteboard, on the surface of which is drawn a map or representation of either the heavens or the earth, the former being called a celestial and the latter a terrestial globe. The oldest example of a terrestrial globe known is that constructed at Nuremberg in 1492. One of the earliest to contain both hemispheres is that in the New York Public Library, and is of date 1506-07.
The celestial globe is intended as a represen tation of the heavens, on which the stars are marked according to their several situations. The terrestrial globe is an artificial represen tation of the earth, exhibiting its great divi sions. The axis of the earth is an imaginary line passing through its centre, and the wire on which the artificial globe turns represents this line. The poles of the earth are the ex tremities of this axis. The brazen meridian is the circle in which the artificial globe turns, divided into 360 degrees. A degree of a great circle in the heavens is a space nearly equal to twice the apparent diameter of the sun, or to twice that of the moon when considerably elevated above the horizon. A degree on the equator of a terrestrial globe represents 60 geographical miles or 69.2 English miles.
Great circles, such as the equator, ecliptic and the colures, divide the globe into two equal parts; small circles, as the tropics, polar circles, parallels of latitude, etc., divide the globe into two unequal parts. Meridians, or lines of longitude, are semi-circles cutting the equator at right angles. In English maps and globes the first meridian is a great circle supposed to pass through the Royal Observatory at Green wich. The equator, when referred to the heavens, is called the equinoctial, because when the sun appears in it the da_ys and nights are equal all over the world. The declination of the sun, stars and planets is counted from the equinoctial north and south. The ecliptic is a
great circle in which the sun makes his ap parent annual progress among the fixed stars; it is the real path of the earth around the sun. The zodiac on the celestial globe is a space which extends about 8 degrees on either side of the ecliptic. Within this belt the motions of the planets are performed. The ecliptic and zodiac are divided into 12 equal parts called signs, each containing 30 degrees; and the sun makes his apparent annual progress through the ecliptic at the rate of nearly a degree In a day. The colures are two great circles of the celestial sphere, one of which passes through the celestial poles and the equinoxes, and the other through the solstices and the celestial poles. The tropics are two smaller circles, each 28' from the equator, with which they are parallel; the northern is called the tropic of Cancer, the southern the tropic of Capricorn. The polar circles are two small circles parallel to the equinoctial, at the distance of 66° 32' from it, and 28' from the poles.
Horizon when applied to the earth is either apparent or real. The sensible or visible hori zon is the circle which bounds our view, where the sky appears to touch the earth or sea. It extends only a few miles. The real or true horizon is an imaginary plane passing through the centre of the earth parallel to the sensible horizon. The wooden horizon circumscribing the artificial globe represents the true horizon on the earth; it is divided into several con centric circles arranged in the following order: One containing the 32 points of the compass divided into half and quarter points; another with the 12 signs of the zodiac, with figure and character of each sign; and another having the days of the month answering to each degree of the sun's place in the ecliptic, and the 12 calendar months. The cardinal points of the ecliptic are the equinoctial and the solstitial points, which mark out the four seasons of the year.