An 18th Century brass and ebony framed octant signed on the maker's bone plaque CHAs. JONES MAKER LIVERPOOL with double 'pin-hole' sight and slide, five shades, mirrors, the index arm with framed vernier scale, tangent screw and clamp, the arc with bone scale divided 0°-95°,on three brass pillar feet in stepped wooden case - 13½in(34.3cm)wide