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A large late 18th-Century English lacquered-brass theodolite
細節
A large late 18th-Century English lacquered-brass theodolite
signed W. & S. JONES, 30 Holborn LONDON, the 16-inch long telescope with undermounted bubble level, rack and pinion adjustment to the objective and sliding focusing to the eyepiece with sliding dust-cover, mounted over the vertical half-circle, one side with a 30°-0-30° Diff. of Hypo & Base scale, the other with silvered 90°-0-90° scale and vernier with magnifier, raised on two A-frame suports with finescrew adjustment over the 8-inch diameter horizontal circle with twin bubble levels, glazed compass with engraved windrose, engraved circumference scales 1-360° and in four quadrants, edgebar needle and clamp, the edge with chamfered and silvered degree scale with twin verniers and magnifier, finescrew adjustment and clamp, raised on a threaded four-screw tripod mounting with finescrew adjustment and clamp
14in. (35.6cm.) high
signed W. & S. JONES, 30 Holborn LONDON, the 16-inch long telescope with undermounted bubble level, rack and pinion adjustment to the objective and sliding focusing to the eyepiece with sliding dust-cover, mounted over the vertical half-circle, one side with a 30°-0-30° Diff. of Hypo & Base scale, the other with silvered 90°-0-90° scale and vernier with magnifier, raised on two A-frame suports with finescrew adjustment over the 8-inch diameter horizontal circle with twin bubble levels, glazed compass with engraved windrose, engraved circumference scales 1-360° and in four quadrants, edgebar needle and clamp, the edge with chamfered and silvered degree scale with twin verniers and magnifier, finescrew adjustment and clamp, raised on a threaded four-screw tripod mounting with finescrew adjustment and clamp
14in. (35.6cm.) high