Ladew Belting Strength Computer Circular Slide Rule by Whitehead and Hoag

Leather belting produced from cowhide tanned in a solution with ground oak bark had been manufactured in New York City from the 19th century. By the end of the century, the firm of Fayerweather & Ladew in Glen Cove, N.Y., had developed methods of waterproofing leather belting so that it could be used in wet and humid conditions. After the death of Edward R. Ladew in 1905, the firm operated as Estate of Edward R. Ladew. It was renamed Edw. R. Ladew Co., Inc., about 1919, and in 1920 it was sold to Graton & Knight Manufacturing Co. of Worcester, Mass.

To publicize its products, the company began distributing the Ladew Belting Strength Computer in 1914. This tan circular slide rule was made by the Whitehead & Hoag Company of Newark, N.J., under a June 6, 1905, patent for printing on pyroxylin (celluloid). It has a rotating disc and another rotating circular segment, pivoted about a metal rivet and attached to a rectangular celluloid base. The logarithmic scales allow computation of the horsepower a leather belt of known quality will transmit, given the width of the belt, the diameter of the pulley, and the rate of revolution of the pulley. The scales also make it possible to calculate the working strain of the belt, according to the kind of belt used and the horsepower transmitted. Instructions are provided on the back of the instrument.

For a linear slide rule for computations relating to cloth belting, see the Computer for Belting and Computer for Shafting made by J. A. & W. Bird & Co. of Boston (1988.0323.02). For information on Whitehead & Hoag, see 1984.1080.01.

References: Frank R. Norkross, A History of the New York Swamp (New York: The Chiswick Press, 1901), 103–107; Richard E. Roehm, "Process of Printing Upon Pyroxylin Materials" (U.S. Patent 791,503 issued June 6, 1905); Library of Congress, Catalogue of Copyright Entries, part 1, group 2, n.s., vol. 11, no. 8 (Washington, D.C., 1914): 754; "Ladew Belt Mill Sold," New York Times (February 13, 1920), 23; "Business Changes," Steam 25, no. 4 (May 1920): 145; accession file.

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