The sextant has a polished brass frame and a wooden handle. The tangent screw and clamping screw are positioned on the back of the index arm. The sextant has four shades, one red, two orange, and one green, as well as three horizon shades, two orange and one green. Index-glass adjustment is made by a screw and on the horizon glass by a thumbscrew and worm gear. Attached to the sextant is a threaded telescope bracket in two parts, fitted for correcting collimation error. It has perpendicular adjustment by a rising-piece and a milled knob. The telescope is 127 mm in length with an inverted image and two parallel cross wires. A second telescope is 58 mm in length with an erect image. The sight-tube is 89 mm in length with a rotating shaded eyepiece and a choice of three red shades. The sextant is contained in a mahogany keystone box, with a trade label in the lid for Henry Hughes and Son, 59 Fenchurch Street, London. There is also a circular handwritten label ‘ETA Helen, Francis, Isabel, Gordon & Pauline gave this instrument to Father on his birthday 8th December 1908’.

The instrument has a b rass scale from -2° to 137° by 30 arcminutes, measuring to 124°. The sextant has a brass vernier measuring to 30 arcseconds, with zero at the right.

Jesse Ramsden (1735-1800) was one of the leading London instrument makers in the late 18th century.