Fuel-Steam Calculator Circular Slide Rule for Norfolk & Western Railway, invented by Fred Q. Saunders

This two-sided white plastic circular slide rule helped railroad procurement officers determine the amount and cost of coal or oil needed to efficiently operate the boiler of a train engine. It consists of three concentric discs, with the two smaller discs on the front and back and one large disc in the middle. The metal fastener holding the discs together is tarnished. On the front, the outer edge of the large disc bears an evenly-divided scale for "Fuel Cost per Million Btu's and Steam Cost per 1000 lbs." The smaller disc has scales for coal cost per ton/oil cost per gallon, BTUs per pound, and evaporation for a high viscosity of fuel. A bell-shaped indicator has a scale for the weight of oil in pounds per gallon.
On the back of the instrument, from the outside in, there are scales and windows for reading the feed water temperature (in degrees Fahrenheit), difference in height (in BTUs per pound), steam pressure (in pounds per square inch), boiler efficiency, the heat value of fuel (in BTUs per pound), a boiler at high pressure, the factor of evaporation and equivalent evaporation, saturated steam pressure (in degrees Fahrenheit), and steam pressure (in pounds per square inch). There is a hairline indicator. The instrument fits into a black leather case.
The front of the device is marked: FRED Q. SAUNDERS (/) RICHMOND, VIRGINIA; FUEL-STEAM CALCULATOR; PAT. 2,328,881. The indicator on the front is marked: N & W (/) Ry. (/) CARRIER OF (/) FUEL SATISFACTION. This is the logo for the Norfolk & Western Railway, which transported coal east from the Pocahontas Coal and Coke Company in the Appalachian mountains. N&W was a relatively small railroad with a significant role in American transportation in the 19th and 20th centuries. It expanded into other activities in 1964 by merging with several other railroads; around this time, it also completed the transition from steam-powered to diesel locomotives. In 1998, the company was merged into Norfolk Southern Corporation.
Inside one of the windows on the back of the instrument is marked: 459; WHITEHEAD-HOAG, NEWARK, N.J. Founded in 1892 and in business until 1959, Whitehead and Hoag was a major producer of paper and plastic advertising novelties. Headquartered in Newark, it had branch offices in about thirty cities around the world. For other slide rules made by this company, see 1987.0221.02 and those described by the MIT Museum and Dick Rose's Catalog for Vintage Instruments (October 2000) at their web sites.
Besides his patent on this device, Fred Q. Saunders of Richmond, Va., copyrighted a "Fuel Steam Calculator Manual" on July 2, 1945 (cit. no. 21463). In 1952, he received patent no. 2,763,873 for a portable, collapsible bath tub to be used on hospital beds.
References: Fred Q. Saunders, "Fuel Engineer's Calculator" (U.S. Patent 2,328,881 issued September 7, 1943); Library of Congress Copyright Office, Catalog of Copyright Entries: Part 1, Books, Group 2, Pamphlets, Etc., new ser. 42 (1945): 397; Mason Y. Cooper, "An Introduction to the Norfolk & Western Railway," Norfolk & Western Historical Society, http://www.nwhs.org/about_nw.html; Thomas W. Dixon, Jr., Appalachian Coal Mines & Railroads (Lynchburg, Va.: TLC Publishing, Inc., 1994); Joseph T. Lambie, From Mine to Market: The History of Coal Transportation on the Norfolk and Western Railway (New York: New York University Press, 1954); "Whitehead and Hoag Collection," Nehushtan Antiques, http://www.nehushtanantiques.com/whitehead_and_hoag.html.
Currently not on view
Object Name
slide rule
date made
Whitehead & Hoag Company
Physical Description
plastic (overall material)
metal (part material)
overall: 15.3 cm x 15.3 cm x .9 cm; 6 1/32 in x 6 1/32 in x 11/32 in
place made
United States: New Jersey, Newark
ID Number
accession number
catalog number
Rule, Calculating
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Slide Rules
Data Source
National Museum of American History, Kenneth E. Behring Center


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