overall: .2 cm x 26 cm x 7 cm; 3/32 in x 10 1/4 in x 2 3/4 in
United States: Illinois, Maywood
By the mid-20th century, rules distributed by manufacturers to ease calculations relating to their products had become quite common. The three logarithmic scales on this rectangular white, yellow, and blue cardboard instrument determine the load (in pounds), size (in inches), and pounds per inch deflection for metal springs, given the PSI, mean diameter of the wire, and number of coils. Six metal rivets hold the rule together. The front top left corner is marked: BARNES • GIBSON • RAYMOND (/) DIVISION OF ASSOCIATED (/) SPRING CORPORATION (/) DETROIT AND ANN ARBOR (/) MICHIGAN. The front top right corner is marked: SPRING (/) DATA (/) COMPUTER. The back left end is marked: Copyright 1943 (/) Associated Spring Corp. (/) Bristol, Conn. The back right end is marked: Mfd. Perry Graf Corp. (/) Maywood, Ill. U.S.A. The instrument fits in a tan paper envelope.
Wallace Barnes (1827–1893) began manufacturing springs for clocks and hoop skirts in Bristol in 1857. His firm expanded into springs for bicycles and automobiles after his death and became Barnes-Gibson-Raymond in Detroit in 1922 as a result of acquisitions. It was renamed Associated Spring Corporation in 1923 and became a public company in 1946. The name Barnes Group was adopted in 1976, and by 2012 the headquarters were again located in Bristol. For more on Perrygraf, see 1979.3074.03.
References: Tom Wyman, "Slide Chart Calculators—A Modest Proposal," <i>Journal of the Oughtred Society</i> 13, no. 1 (2004): 6–10; "History," <i>Barnes Group, Inc.</i>, http://www.bginc.com/about_history.php; Carlyle F. Barnes, <i>Associated Spring Corporation</i> (New York: Newcomen Society in North America, 1963).