Details
A late 18th-century brass theodolite,
signed on the horizontal plate Ramsden London and further engraved Tangents in 100ths of the radius, the upper telescope with sliding eyepiece tube focusing engraved with cross-wires, object glass with slight green tint, screw-on lens cap, and bubble level, located with two clamps on the half vertical circle, with external rack gear, the shaped frame with axis raised on two shaped supports, the half vertical circle engraved on one side 80°-0-80°, with vernier engraved on the pinion mounting, the other wide with two scales, the upper divided 30°-0-30°, the lower 100°-0-100°, the horizontal plate with compass box, the silvered dial with finely engraved star to the cardinal points, the plain bar needle with cap, the silvered dial divided in four quadrants, the upper stepped horizontal circle divided 0-360°, with level and cross-bubble, the horizontal circle adjusted by internal rack and pinion gear, the upper face with large vernier divided 100°-0-100°, the tripod or staff mounting incorporating the lower telescope which divides into two sections, the trunnion mounting with fine vertical clamp adjustment, the instrument -- 13¼in. (33.6cm.) high, contained in a fitted pine carrying case with swan-neck brass carrying handle -- 16in. (40.7cm.) high
See Colour Illustration and Detail
signed on the horizontal plate Ramsden London and further engraved Tangents in 100ths of the radius, the upper telescope with sliding eyepiece tube focusing engraved with cross-wires, object glass with slight green tint, screw-on lens cap, and bubble level, located with two clamps on the half vertical circle, with external rack gear, the shaped frame with axis raised on two shaped supports, the half vertical circle engraved on one side 80°-0-80°, with vernier engraved on the pinion mounting, the other wide with two scales, the upper divided 30°-0-30°, the lower 100°-0-100°, the horizontal plate with compass box, the silvered dial with finely engraved star to the cardinal points, the plain bar needle with cap, the silvered dial divided in four quadrants, the upper stepped horizontal circle divided 0-360°, with level and cross-bubble, the horizontal circle adjusted by internal rack and pinion gear, the upper face with large vernier divided 100°-0-100°, the tripod or staff mounting incorporating the lower telescope which divides into two sections, the trunnion mounting with fine vertical clamp adjustment, the instrument -- 13¼in. (33.6cm.) high, contained in a fitted pine carrying case with swan-neck brass carrying handle -- 16in. (40.7cm.) high
See Colour Illustration and Detail