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Surveyor's pocket sextant.

1795-1805

Pocket brass framed sextant

1785-1795

Brass framed pocket sextant.

1795-1804

Pocket brass framed sextant.

1795-1804

Aircraft bubble sextant.

1942-1947
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.

Pocket brass sextant.

1825-1835
Pocket brass framed sextant, with mahogany keystone box, made by Jesse Ramsden, Piccadilly, London, England, 1785-1795. Polished brass frame and limb, no handle. Signed on the crossbar: ‘Ramsden London’. Brass scale from -2° to 145° every 30', measuring to 125° (digits read from the pivot). Brass vernier to 1', zero at the left. The tangent screw is on the front of the index arm; the clamping screw is on the back. Two shades (both red); no horizon shades. Index-glass adjustment by screw; adjustment of the horizon glass by fixed milled screw and by Dollond's extended lever and clamp, operated from beneath the telescope bracket. Detached telescope bracket, to be fit to the frame by a dovetail mount; perpendicular adjustment by rising-piece and a milled screw. Detached magnifier on a 35-mm swivelling arm. Telescope (62 mm) erect image. Shaded eyepiece (red).

Pocket brass framed sextant

1785-1795