SIGN, in astronomy, a portion of the ecliptic or zodiac, containing 30 degrees, or a 12th part of the complete circle.
The first commences at the point of the equator through which the sun passes at the time of the vernal equinox; and they are counted onward, proceeding from W. to E., according to the annual course of the sun, all round the circle. The names of the 12 signs, in the order in which they follow each other, are as follows: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Li bra, Scorpio, Sagittarius, Capricornus, Aquarius, Pisces. It is to be remarked that the above are also the names of the 12 constellations of the zodiac; and in an cient times (more than 200 years before our era), the places of the signs and the constellations were coincident; but owing to the motion of the earth's equator, by which the equinoctial points are carried backward on the ecliptic about 50' 6" an nually, the intersections of the ecliptic and equator, and consequently the com mencement of the signs, now correspond to different stars, the first point of the sign Aries being at present near the be ginning of the constellation Pisces. On
this account care must be taken not to confound the signs of the zodiac, which are fixed in respect of the equinoxes, with the constellations, which are movable in respect of those points.
In algebra, a symbol indicating an op eration to be performed, or a relation sub sisting between two quantities. Of the former kind, those most commonly used are, + for addition, — for subtraction, X for multiplication, for division, V for the square root, 3 1/ for the cube root, n V for the nth root, etc. The sign de noting relations are, = equal to, > great er than, < less than, etc.