dem i circle

An instrument for measuring and indicating angles. It resembles a protractor, and has sights at each end of its diameter, also sights at each end of a rule or alidad a, which has an axis over the center of the circle, so as to sweep the graduated arc. A given object being observed from a station, through the sights, the alidad a is adjusted so that the other object is observable through the sights. The point of the rule then indicates the angle. In the middle of the instrument is a compa to show the magnetic bearings. By providing the instrument with telescopes, a considerable degree of accuracy may be attained, and more distant points conveniently observed. It is a modest substitute for a theodolite. The plane of the instrument is placed horizontally for taking distances, and vertically for heights. ( Knight.) *dem i-coronal, s. A half-coronet. "Marquis Dorset, bearing a scepter of gold, on his head a dem i -coronal of gold."-Shakesp.: Henry VIII., iv. 1 (Stage directions). *dem i-cro , s . An instrument for taking the altitude of the sun and stars.