09-039B. English, 1st quarter 20th century, signed on the front face "STANLEY-BOUCHER CALCULATOR PATENT." The 2 1/8" diameter body is made of nickel plated brass, with flat beveled glass faces. The front face is movable, with a moveable cursor needle; the rear face is fixed, with a movable cursor needle and a rotation counter. The slide rule is in very good working condition.
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