in geometry, a plane figure comprehended by a single curve line, called its circumference, to which right lines drawn from a point in the middle, called the centre, are equal to each other. To find the area of a circle, see PRACTICAL GEOMETRY.

Circles of the sphere. See GEOGRAPHY and ASTRONOMY.

Circles of latitude. See GEOGRAPHY.

Circles of longitude. See GEOGRAPHY.

Horary Circles, in dialling, are the lines which show the hours on dials, though these be not drawn circular, but nearly straight. See DIALLING.

Horary Circle, on the globe. See GEOGRAPHY.

Polar Circle. See GEOGRAPHY.

logic, or logical Circle, is when the same terms are proved in orbe by the same terms; and the parts of the syllogism alternately by each other, both directly and indirectly.

Circles of the empire, such provinces and principalities of the German empire as have a right to be present at diets. Maximilian I divided the empire into six, and some years after into ten circles. This last division was confirmed by Charles V. The circles, as they stand in the Imperial Matricola, are as follows, Austria, Burgundy, the Lower Rhine, Bavaria, Upper Saxony, Franconia, Swabia, Upper Rhine, Westphalia, and the Lower Saxony.