Definition

An instrument consisting essen­tially of a circle graduated in DEGREES, to which is attached one fixed arm and two arms pivoted at the centre and provided with clamps so that they can be set at any angle to the fixed arm, within the limits of the instrument. It is used for finding a ship's POSITION, when the angles between three fixed and known points are measured. In British terminology, a perspex (or transparent plastic) device used when the MARKS are too close for the use of a STATION POINTER. This instrument has replaced the CUST PROTRACTOR.