A late 18th Century brass graphometer signed Benneke a'Berlin 1792, the semi-circle divided 0°-180°(x2), with two fixed folding sights, the alidade with silvered compass box divided 0°-180°, with needle and engraved compass rose, signed Benneke a'Berlin and attached to alidade by four'butterfly'nuts, with two folding sights and framed verniers, on staff mounting with universal ball and socket mounting - 14in.(36cm)wide