This one-sided, five-inch steel linear slide rule is painted white. The scales are not lettered, but on the base they are equivalent to A and D scales and on the slide they are the equivalent of B, CI, and C scales. The bottom of the base is marked: GUEDON. CAMDEN. NEW JERSEY. It is also marked: PATENT PENDING and MADE IN U. S. A.
The base has grooves along the top and bottom of both the front and the back. The front grooves hold a celluloid indicator with concave curves on both sides. The back grooves hold a piece almost as wide as the base that serves as a support for the slide. The slide is a narrower metal piece, hooked to the support at both ends. The front of the support has a table for converting fractions to decimals; on the back are scales of 12.5 cm, divided to millimeters, and of 5 inches, divided to 32nds of an inch. The rule fits in a cardboard sleeve coated with brown synthetic leather.
According to a letter in the Keuffel & Esser collection at the MIT Museum, the Guedon company was making rules of this type in 1943 and selling them wholesale for 50 cents.
Reference: International Slide Rule Museum, "Miscellaneous USA," http://sliderulemuseum.com/MiscUSA.htm.
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