Early Pocket Sextant with detachable telescope – Harris London and Hamburg
Early and complete pocket sextant in a fitted leather case lined with vervet. The same instrument can be found in the Greenwich National Maritime Museum (NAV1150) from which the following description is taken.
The sextant consists of circular polished brass plates with a lid that when screwed on the back of the instrument serves as the handle. The index arm is moved by a milled screw on the upper plate. The instrument has two index shades in red and green, which are moved by levers. Horizon-glass adjustment is made by a milled key shipped in the upper plate. Attached to the sextant is a single lens magnifier on a 45mm swivelling arm. The telescope is 65 mm in length with an erect image and an angled bracket for attaching it to the instrument by a milled screw. It has a sliding pinhole shutter. The instrument has an inlaid silver scale from -5° to 170° by 30 arcminutes, measuring to 139° (the digits are read from the pivot). The sextant has a silver vernier, reading to 1 arcminute, with zero at the left.
The eyepiece of the Greenwich instrument is missing.
Date: ca 1850
D compass: 74 mm (2.9 in)
HWL case: 45x115x93 mm (1.8×4.5×3.5 in)
Signed: W. Harris & Co, 50 Holborn London & at Hamburg