One fourth of a circle, or an arc of 90 degrees.

园周四分之一(即九十度弧)。

An instrument containing a scale for measuring angles up to 90 degrees, usually in the form of an arc of 45 degrees, with a movable arm, formerly used in navigation, but now replaced by the sextant.

【航】四分仪。

An instrument for measuring the altitude of heavenly bodies.

【天】象限仪(测量天体高度距离之仪器)。

An instrument for raising a cannon to give it the desired range.

【军】升高炮度器。

Area bounded by such an arc and the radii at its extremities.

四分之一圆形区。