Ebony frame with brass index arm and fittings, inlaid ivory plate on the back of the frame. Tangent screw and clamping screw on the back of the index arm. Three shades (red, red, green); three horizon shades (red, red, green). Index glass adjustment by screw; horizon glass by screw, lever, worm gear and clamping screw. Sight vane missing, pencil head and pencil are missing from the crossbar. Stepped oak box with penciled calculations inside the lid, lock and 1 latch hook.
Materiaal
Signed on the inlaid ivory plate on the crossbar: Simpson & Roberts 34 Strand St Liverpool
