Ebony frame with brass index arm and fittings, inlaid ivory plate on the back of the frame (missing). Tangent screw and clamping screw on the back of the index arm. Three shades (two red, one green). Index glass adjustment by screw; horizon glass by screw, lever, worm gear and clamping screw. Sight vane with two pinholes and a swiveling shaded shutter (red). Ivory pencil head, pencil missing. No box.
