Slide RulesIndex by Purpose
While many slide rules were made as general calculating instruments, for multiplying numbers and solving equations with squares, cubes, trigonometric functions, and logarithms, many others were made to ease the calculations associated with a specific task. Click on items in the list below to see rules in the collection with an identifiable specialized purpose. For comparison, a few illustrative examples of all-purpose slide rules are shown under the link to General Calculation.
"Slide Rules - Index by Purpose" showing 1 items.
- This is one of several slide rules designed for use in psychology. It has a white plastic envelope that holds a paper slide. The upper part of the envelope has scales labeled A (a 23-centimeter ruler, divided to millimeters), N (number of cases), PE (probable error, running from 1 to 10), sigma (running from 1 sigma to 10 sigma), and c (probability that an event happened by chance). The top part of the slide has scales labeled r (running from 0.97 down to 0.00, divided logarithmically) and B (logarithmically divided from 0.05 to 0.20).
- The lower part of the envelope has scales labeled sigma (standard deviation) and D (a standard slide rule logarithmic scale for multiplication, running from 10 to 140). The lower part of the slide has scales labeled sigma1.2, sigmaM (standard error of measurement), and C (divided logarithmically and running from 10 to 140). The center of the slide has the line graph r1/2 /III to r1I. The back of the envelope has five more line graphs.
- Instructions are provided on the back of the slide and on a leaflet received with the rule. The lower left corner of the envelope is marked: Designed by Jack W. Dunlap and Albert K. Kurtz. The lower right corner is marked: Copyright 1933 by The Psychological Corporation. James McKeen Cattell, Robert Sessions Woodworth, and Edward Lee Thorndike founded the Psychological Corporation in New York City in 1921 to market psychological tests and educational materials. Jack W. Dunlap (1902–1977) and Albert Kenneth Kurtz (1904–1992) were academic psychologists interested in graphic computation charts. They copyrighted the D-K Statistical Slide Rule again in 1938, after which it was sold as a duplex wooden rule. After World War II, Dunlap went into industrial psychology.
- References: advertisement, Science 79, no. 2041 (February 9, 1934), back matter, 7; Library of Congress Copyright Office, Catalog of Copyright Entries: Part 1, Books, Group 2, Pamphlets, Etc., n.s. 31 (1935): 24; Jack W. Dunlap and Albert K. Kurtz, Handbook of Statistical Nomographs, Tables, and Formulas (Yonkers-on-Hudson, N.Y.: World Book Company, 1932); Albert K. Kurtz, "Obituary: Jack W. Dunlap," American Psychologist 34, no. 6 (June 1979): 538; J. McKeen Cattell, "The Psychological Corporation," Annals of the American Academy of Political and Social Science 110 (November 1923): 165–171.
- Currently not on view
- date made
- Psychological Corporation
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- nonaccession number
- catalog number
- Data Source
- National Museum of American History, Kenneth E. Behring Center