細節
A 19th-Century French-pattern brass graphometer,
unsigned, the compass with silvered scale and edge-bar needle on jewelled pivot, the horizontal plate with engraved scale 0°-180° -180°-0°, with two fixed sights, the rotating alidade with twin vernier scales and two sights, the underside with ball-and-socket staff mounting, in fitted pine case with brass carrying handle -- 12½in. (31.8cm.) wide
See Illustration
unsigned, the compass with silvered scale and edge-bar needle on jewelled pivot, the horizontal plate with engraved scale 0°-180° -180°-0°, with two fixed sights, the rotating alidade with twin vernier scales and two sights, the underside with ball-and-socket staff mounting, in fitted pine case with brass carrying handle -- 12½in. (31.8cm.) wide
See Illustration