An oxidised brass tulip frame vernier sextant signed on the arc 'J. Sewell Liverpool Maker to the Admiralty' with silvered scale, swivel magnifier, the index arm with tangent screw and clamp -- 8½in. (21.5cm.) radius, seven shades, two telescopes and mirrors, in wooden case with trade label for Andrew Christie 27 Clyde Place Glasgow

細節
An oxidised brass tulip frame vernier sextant signed on the arc 'J. Sewell Liverpool Maker to the Admiralty' with silvered scale, swivel magnifier, the index arm with tangent screw and clamp -- 8½in. (21.5cm.) radius, seven shades, two telescopes and mirrors, in wooden case with trade label for Andrew Christie 27 Clyde Place Glasgow