Pocket sextant made by Charles Augustus Schmalcalder, London, about 1830. Lacquered brass frame and limb, the detached screw-in handle is missing. Signed on the index arm: Schmalcalder | London. Polished brass scale from -2° to 134° every 30', measuring to 120° (digits are read from the pivot). Brass vernier to 1', zero at the left. There is no tangent or clamping screw; the index arm is moved by hand, by a milled knob. No shades. Index- and horizon-glass adjustment by screws and a fixed milled screw. Sight vane with one pinhole. A mahogany keystone box.
Details
- Category:
- Surveying
- Collection:
- Sir Henry Wellcome's Museum Collection
- Object Number:
- 1981-113
- Materials:
- brass (copper, zinc alloy), glass and wood (unidentified)
- type:
- pocket sextant
- credit:
- On loan from the Wellcome Trust
