Surveyor's pocket sextant.

Surveyor's pocket sextant made by William Cary, London, about 1800. Lacquered brass frame, polished limb, a detachable wooden handle. Signed on the crossbar: Cary London. Brass scale from -5° to 150° every 1°, measuring to 125° (digits read from the pivot). Brass vernier to 1', zero at the left. There is no tangent or clamping screw; no shades. Index glass without adjustment; adjustment of the horizon glass by a fixed milled screw. Sight vane with one pinhole. Wooden keystone box containing in the lid a label of the Geological Survey of Great Britain marked in MS: H.W. Bristow | 28 Jermyn Street | SW [and] agenda | 6747. Used for field mapping during the Peninsular War, 1808-1814.