Pocket brass framed sextant.

Pocket sextant made by John Dollond, London, about 1800

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Pocket sextant made by John Dollond, London, about 1800
Science Museum Group
© The Board of Trustees of the Science Museum

Pocket sextant made by John Dollond, London, about 1800. Lacquered brass frame and limb, a hinged wooden handle. Signed on the index arm: Dollond London. Polished brass scale from -2° to 154°

every 30', measuring to 126° (digits read from the pivot). Brass vernier to 1', zero at the left. There is no tangent screw; the clamping screw is on the back of the index arm. Two shades (red and green). Index- and horizon-glass adjustment by screws. Magnifier (single lens) on a 48 mm swivelling arm. Sight vane with one pinhole and a swivelling shade (missing). A fitted square mahogany box.

Details

Category:
Surveying
Object Number:
1907-74
Materials:
brass (copper, zinc alloy), glass, felt, mahogany (wood) and sapele (wood)
Measurements:
overall: 67 mm x 130 mm x 225 mm, .51kg
type:
pocket sextant
credit:
J.C. Stevens (Auction Sales)