Ball recording sextant with case.

Ball recording sextant with brass and alloy frame and plastic handle in rectangular fitted wooden box with a leather strap, made by the Mergenthaler Linotype Company, Brooklyn, New York, USA, 1944. Consists of scale (0° to 90°), on reverse, with 1°’ divisions and micrometer (1’), day and night telescopes (236mm) and no filter shades. In use, the celestial body is viewed directly and instead of a plumb bob, a falling steel ball records the altitude on a screen, and is read off the scale and micrometer.