Octant, [ebony], ivory/brass/mahogany, Spencer Browning & Rust, London, [1790-1810]
Octant, [ebony], ivory and brass, in mahogany box, Spencer Browning & Rust, London, made for D McGregor Greenock, [1790-1810] (OF). Sextant brought to Australia in 1839 by H J Sloan (SB).
Ivory scale, radius 240mm, divided in graduations of 1-100 (degrees). The horizon is sighted by means of a sighting telescope mounted on one of the radii of the secor, An index arm is pivoted at the centre of the graduated arc and a miror mounted at that pint. A second mirror is mounted apposite the sighting telescope on the opposing radii. There are three shades each for the index and horizon glasses. Inside a mahognay box.
Octant marked "Spencer Browningt & Rust. London. / Made for. D.Mc.Gregor. Greenock"