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Ebony and brass octant.

Ebony and brass octant.

1777-1810
Octant made of ebony and brass

Octant made of ebony and brass

1830-1835
Mahogany and brass octant.

Mahogany and brass octant.

1770-1776
Ebony and brass octant.

Ebony and brass octant.

1815-1825
Ebony octant on pillar stand with artificial horizon.

Ebony octant on pillar stand with artificial horizon.

1750-1760
Ebony and brass octant.

Ebony and brass octant.

1855-1865
Brass framed octant with case.

Brass framed octant with case.

1794-1801
Mahogany and brass octant.

Mahogany and brass octant.

1764
Brass framed octant.

Brass framed octant.

1758-1763
Ivory and ebony octant.

Ivory and ebony octant.

1837-1842
Mahogany and brass octant.

Mahogany and brass octant.

1775-1785
Ivory and ebony octant.

Ivory and ebony octant.

1835-1845
Ebony and brass octant.

Ebony and brass octant.

1855-1860
Ebony and brass octant.

Ebony and brass octant.

1790-1800
Ebony and brass octant.

Ebony and brass octant.

1795-1804
Mahogany and brass octant.

Mahogany and brass octant.

1745-1755
Octant by an unknown English maker, about 1750. Mahogany frame, limb and index arm; brass fittings and a brass stop for the index arm; an inlaid ivory plate in the crossbar (with obliterated text). Inlaid boxwood transversal scale from 0° to 90° and vice versa every 20' (for zenith distance), measuring to 90°. The scale reads to 2' by use of the ivory-lined fiducial edge at the end of the index arm. Two socket shades (red and orange). Index-glass adjustment by screw; adjustment of both horizon glasses by screws, and levers, wing nuts, and milled clamping screws. There is no tangent screw, the clamping screw is on the back of the index arm. The sight vane has two pinholes and a swivelling shutter; the back sight vane has one pinhole. In a stepped oak box.

Mahogany and brass octant

1745-1755
Octant with an artificial horizon patented by John Syeds, London, about 1791, and possibly made by him. Lacquered brass frame, a polished brass limb. Marked on the frame: Ino Seyds | Patentee No 12. Marked on the brass case of the artificial horizon: Iohn Seyds's Patent. Brass scale from -2° to 99° every 20', measuring to 99°. Brass vernier to 1', zero at the right. There is no tangent screw; the clamping screw is on the back of the index arm. No shades found, but holes in the frame suggest there may have been index shades. Index-glass adjustment by screw; adjustment of the horizon glass by a lever, wing nut and a milled clamping screw. Adjustment of the third glass, for reflecting the bubble of the artificial horizon, is by lever, wing nut and milled clamping screw. Sight vane with two pinholes and a swivelling shutter; the vane can be moved along the right strut of the frame over a short distance by a milled screw, and clamped into position by a second milled screw. The horizontal position of the brass case containing the bubble level can be adjusted along the left strut of the octant frame by a milled screw, and clamped into position by a second milled screw. The artifical horizon consists of a bubble level that, when the instrument is held vertically, is reflected by the third glass into the silvered part of the horizon glass, when the horizon is not visible. in box... not seen, WMB

Brass framed octant fitted with bubble artificial horizon and carrying case

1790-1799