in Geometry, a quantity extended in length only, without any breadth or thickness. It is formed by the flux or motion of a point. See FLUXIONS, and GEOMETRY.

the art of war, is understood of the disposition of an army ranged in order of battle, with the front extended as far as may be, that it may not be flanked.

Line of Battle, is also understood of the disposition of a fleet in the day of engagement; on which occasion the vessels are usually drawn up as much as possible in a straight line, as well to gain and keep the advantage of the wind as to run the same board. See Naval Tactics.

Horizontal Line, in Geography and Astronomy, a line drawn parallel to the horizon of any part of the earth.

Equinoctial Line, in Geography, is a great circle on the earth's surface, exactly at the distance of 90° from each of the poles, and of consequence bisecting the earth in that part. From this imaginary line, the degrees of longitude and latitude are counted.—In astronomy, the equinoctial line is that circle which the sun seems to describe round the earth on the days of the equinox in March and September. See Astronomy and Geography.

Meridian Line, is an imaginary circle drawn through the two poles of the earth and any part of its surface. See Geography Index.

Ship of the LINE, a vessel large enough to be drawn up in the line, and to have a place in a fight.

in Genealogy, a series or succession of relations in various degrees, all descending from the same common father. See DESCENT.

also denotes a French measure containing the 12th part of an inch, or the 144th part of a foot. Geometricians conceive the line subdivided into fix points. The French line answers to the English barley-corn.

Fishing LINE. See FISHING Line.

LINES, in Heraldry, the figures used in armories to divide the shield into different parts, and to compose different figures. These lines, according to their different forms and names, give denomination to the pieces or figures which they form, except the straight or plain lines. See HERALDRY.