ClipArt ETC
"Sextant. An important instrument of navigation and surveying, for measuring the angular distance of two stars or other objects, or the altitude of a star above the horizon..." a, handle; b, c, mirrors; d, ring; e, telescope; f, arm; g, reading-lens; h, arc; i, screw; j, tangent screw. -Whitney, 1911

Sextant

"Sextant. An important instrument of navigation and surveying, for measuring the angular distance of…

An instrument, variously constructed, used especially in surveying.

Theodolite

An instrument, variously constructed, used especially in surveying.