A late 18th-Century lacquered brass graphometer, signed on the alidade Jecker A Paris, the semi-circle divided 0°-180° (X 2) with 2 fixed sights and compass box, with engraved silvered circle, the needle with clamp, the alidade with 2 verniers and twin sights, with universal ball and socket staff mounting, in carrying case - 14ins. (35.5cm.) wide.