Brass circular plates . Signed on the upper plate 'Gilbert & Sons London'. Inlaid silver scale from -5° to 145° by 30', measuring to 129° (digits read from the pivot). Silver vernier to 1', zero at left. Index arm moved by milled knob on the upper plate. Horizon glass adjustment by milled knob shipped in the upper plate. One shade (red), lever operated. Magnifier (single lens) on 45 mm swivelling arm. Sliding shutter with pinhole and shade (red). Radius 1.75'' (44 mm), diameter 67 mm. Two screws to hold the upper plate are missing. Contained in a fitted wooden box with an artificial glass horizon (NAV0019) and a pocket compass (NAV0466).
Belonged to Edward Newell Harrison, clerk of HMS Assistance, went to the Arctic in 1850-52, in search of Franklin, died in the West Indies before 1855.
See artificial glass horizon NAV 0019 which also belonged to him.