Alco Personal Calculator (Simplex Slide Rule and Adder)

This pocket-sized sheet metal instrument combines a one-sided linear slide rule, an adder, and a rule. The sliding bar adder on the front has six bars. The upper parts are for addition, and the lower parts are for subtraction. Round windows in the middle show the result. A metal stylus moves the bars, and there is a zeroing bar at the top. The adder is marked: ALCO (/) + ADDITION (/) – SUBTRACTION (/) PERSONAL (/) CALCULATOR (/) MADE IN JAPAN. The back of the instrument is a slide rule with A and D scales on the base; B, CI, and C scales on the slide; and a clear plastic frameless indicator. The slide may be removed to reveal a scale of 5.5 inches, divided to 32nds of an inch, and a scale of 14 centimeters, divided to millimeters. The right end of the slide is marked: MADE IN JAPAN. The instrument fits in a clear and blue plastic sleeve.

Metal adders were available from at least the 1920s. Compare 1986.0543.01, 1988.0807.04, 1989.0325.01, 1989.0709.02, and 1994.0208.01. In 1937 Carl Kübler, whose German firm made the famous Addiator adder, filed a U.S. patent application for attaching an adder to a metal slide rule. By the 1950s, an unknown company in Japan made "personal calculators" (such as 1992.0548.01) and sometimes attached slide rules. In 1968 Al Nyman & Son, Inc., of New York, N.Y., took out a trademark for "alco" for drawing compasses and pocket calculators (serial number 72278404). Perhaps the firm distributed this instrument, although the style of "alco" in the trademark does not match the mark on the object. Nyman is known to have sold a Mannheim slide rule under the alco trademark.

References: Carl Kübler, "Means for Mounting an Adding and Subtracting Device on Slide Rules" (U.S. Patent 2,153,089 issued April 4, 1939); David D. McFarland, "Addition and Subtraction With Slide Rules and Allied Instruments, Part I," Journal of the Oughtred Society 12, no. 2 (2003): 27–36; U.S. Patent and Trademark Office, Trademark Electronic Search System.

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