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Octant made of ebony and brass

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1830-1835

Octant made by John Smith, London, about 1830. Ebony frame and limb with brass index arm and fittings; an inlaid ivory plate on the crossbar. Signed on the plate on the crossbar: J. SMITH 126 Wapping LONDON. Radius 9 inches. Inlaid ivory scale from -3° to 96°, every 20'. 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); three horizon shades (two red, one green). Index-glass adjustment by screw; adjustment of the horizon glass by a fixed screw and a lever, worm gear and a milled clamping screw. The sight vane is lacking. No box. (B 696)

Ebony and brass octant.

Astronomy

1777-1810

Octant signed ‘Watkins Charing Cross London’, made c. 1800. Ebony frame and limb, brass index arm and fittings, inlaid ivory plates on the crossbar and the back of the frame. The fouled anchor stamp was applied to instruments divided on a dividing engine; in this case either that of Jesse Ramsden (indicated by initials IR) or his apprentice Edward Pritchard (indicated by initials EP). The tangent screw is on the front of the index arm; the clamping screw is on the back. Three socket shades (two red, one green). Index-glass adjustment by screw; adjustment of the horizon glasses by screws, and by levers, wing nuts and milled clamping screws. The sight vane has two pinholes and a swivelling shade (red); the back sight vane has one pinhole. An ivory-capped pencil is fitted in the crossbar. No box.

Ebony and brass octant.

Astronomy

1790-1800

Octant made by Thomas Ripley and Son, London, about 1795. Ebony frame and limb with brass index arm and fittings; inlaid ivory plates on the crossbar and the back of the frame. Signed on the plate on the crossbar: Made by Tho.s Ripley & Son Hermitage Bridge | London. Marked on the scale (stamped) [fleur-de-lis]. Inlaid ivory scale from -2° to 99° every 20', measuring to 89°. Ivory vernier to 1', zero at the right. The tangent screw is on the front of the index arm; the clamping screw is on the back. Three socket shades (two red, one green). Index-glass adjustment by screw; adjustment of the horizon glass by lever and worm gear by square-headed screw and a detached key (missing); adjustment of the back horizon glass by lever, wing nut and clamping screw (missing). The sight vane has two pinholes and a swivelling shutter; the back sight vane has one pinhole. A pencil or screwdriver is missing from the crossbar. No box.

Ivory and ebony octant.

Astronomy

1835-1845

Octant with ebony frame and 9-inch radius limb with brass index arm and fittings and inlaid ivory plates on the crossbar and back; made by S.W. Silver and Co, 66 & 67 Cornhill. London, London, 1835-1845. Fitted with ivory vernier and scales measuring to 92°, with screw adjustment for the index-glass and similar for horizon glass with lever, worm gear, and milled clamping screw. The sight vane has two pinholes and a swivelling shutter. A pencil or screwdriver is missing from the crossbar, box not present