Details
A rare French 18th-Century circular slide rule,
with silvered inner and outer ring dials, the revolving inner ring with lacquered brass spokes and screw fine adjustment, the outer ring on brass columns on four-branch cast iron base, rotatably mounted on ebonised wood base, the oxidised brass index arm with clamp-screw at centre, fine wire index, screw fine adjustment and provision for scale magnifier, the outer ring with six various scales, the inner ring divided 0-1000, with wood cover -- 18½in. (47cm.) diameter
See Colour Plate
with silvered inner and outer ring dials, the revolving inner ring with lacquered brass spokes and screw fine adjustment, the outer ring on brass columns on four-branch cast iron base, rotatably mounted on ebonised wood base, the oxidised brass index arm with clamp-screw at centre, fine wire index, screw fine adjustment and provision for scale magnifier, the outer ring with six various scales, the inner ring divided 0-1000, with wood cover -- 18½in. (47cm.) diameter
See Colour Plate