Double sounding sextant made by Thomas Jones, London, about 1830. Two polished brass sextant frames and limbs connected parallel to each other by pillars and a brass plate; two wooden handles, one the front the other on the back of the frames. Signed on the limb of the upper sextant: Thomas Jones 62 Charing Cross London. Marked on the crossbar of the upper sextant: D.170. Two inlaid silver scales, each from -2° to 143° every 20', measuring to 128°. Two silver verniers both to 30". Two index arms, the tangent screw and clamping screw is on top of the upper arm; the lower tangent screw and clamping screw are on the back of the lower frame. No shades. Adjustment of the index and horizon glasses by square-headed screws and a detached key (not found). The magnifier on the upper sextant is on a 80-mm swivelling arm; that on the lower sextant is on a 100-mm swivelling arm mounted on the back of the frame. Threaded telescope bracket in two parts, fitted for correcting collimation error; the bracket is fixed between the two frames. Telescope (165 mm) with a shade (red), erect image. Sight tube (155 mm). The limb of the lower sextant is fitted with a greatest angle clamp (see notes). Box not seen, WMB. A trade label for Thomas Jones, London taken from the box.
Brass double sounding sextant with two sets of divided scales, by Thomas Jones, London, without mahogany case.
Trade card for brass double sounding sextant by Thomas Jones, London.
Accessories for double sounding sextant made by Thomas Jones, London, about 1830. Including six screws and a broken disk.
