This white plastic chart was designed for the U.S. Army Signal Corps. It is a nomogram for finding the range correction in yards of a weapon, by lining up the meteorological correction as a percentage of the range and the range.
On the left is a scale marked “Range Correction in Yds.” On the right is a scale marked “Percentage Meteorological Correction” and on the diagonal between the two is a scale marked “Range in Yds.” According to a label received with the object and stored in the accession file, the object was made in 1945.
The meteorological correction is found from the temperature and wind speed using a related chart called a “sound velocity corrector” (for an example, see 1977.1141.42) .
A mark on the object reads: Range Correction Chart PT-63/TSS-1.
For an explanation of the mathematical theory of this kind of nomogram, see Lipka. For a similar device used for another purpose, see 1985.0636.01.
References:
Joseph Lipka, Graphical and Mechanical Computation. Part I. Alignment Charts, New York: John Wiley & Sons, 1921, pp. 65–
67.
Accession file.
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