Hornyak & Kelly slide rule
A prepatent version of an uncommon rule for determining the weight of metals for given dimensions and shape. Hornyak and Kelly, of Philadelphia, applied for a patent on this slide rule in 1913. This example is marked “Patent applied for”. The patent was finally granted on Jan 2, 1917. The body, under the two slides, is marked “Manufactured and Sold by Hornyak & Kelly, 620 South 51st Street, Philadelphia”. Construction is laminated cardboard. Scales are for thickness on upper stock, width and length on upper slide, type of metal (lead, copper, brass, steel, cast iron, aluminum, water) and shape (oval, round, octagon, hexagon, rectangle) on lower stock, and weight in pounds on lower stock. 14” long, 2 5/8” wide, 11/32” thick. Slight loss to the face and some staining, otherwise good cond. The slides work well
closeup of scales
closeup of maker's name on stock under slides
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