An early 19th-century brass 'Troughton' pattern double frame sextant, signed on the arc with platina scale : Mackenzie & Swygart 15 Cheapside London, with adjustable telescope mounting socket, seven shades and two mirrors, the index arm with platince vernier scale -- 8in.radius; magnifier and tangent screw adjustable, the braced frame with rosewood handle, with three telescope and a trade label for the successons to Crichton Brothers, in shaped mahogany case