Ebony and brass octant.

Octant made by William and Samuel Jones, London, about 1860. Ebony frame and limb with a brass index arm and fittings; an inlaid ivory plate on the crossbar. Signed at the bottom of the index arm: W & S, Jones | 30 Holborn London. Inlaid ivory scale from -2° to 98° every 20', measuring to 90°. Ivory vernier to 1', zero at the right. The tangent screw and clamping screw are on the back of the index arm. Three shades (two red, one green); two horizon shades (both red). Index-glass adjustment by screw; adjustment of the horizon glass by screw, lever, tangent screw and a milled screw. Sight vane with two pinholes and a swivelling shade (red). A capped pencil or screwdriver is missing from the crossbar. An unidentified part is missing. Stepped oak keystone box, painted brown on the outside, containing a MS note about the mean corrections of the instrument, dated January 1889.