in politics, signifies a change in the constitution of a state, and is a word of different import from revolt, with which it is sometimes confounded. When a people withdraw their obedience from their governors for any particular reason, without overturning the government, or waging an offensive war against it, they are in a state of revolt; when they overturn the government, and form a new one for themselves, they effect a revolution.

That which is termed the revolution in Britain is the change which, in 1688, took place in consequence of the forced abdication of James II., when the Protestant succession was established, and the constitution restored to its primitive purity.

Geometry, the motion of rotation of a line about a fixed point or centre, or of any figure about a fixed axis, or upon any line or surface. Thus, the revolution of a given line about a fixed centre generates a circle; and that of a right-angled triangle about one side, as an axis, generates a cone; and that of a semicircle about its diameter generates a sphere or globe.

Astronomy, is the period of a star, planet, or comet, or its course from any point of its orbit, till it return to the same again.

Rewal, a town of Hindustan, in the province of Gundwana, district of Boghela. The suburbs are large. Under the fort runs the Bichanaddy, which has its source twenty miles to the east. It contains a good citadel, built of stone, and the country in the vicinity is well cultivated. Long. 81° 25'. E. Lat. 24° 27'. N.