K2 PerformanceClass Horse Race Wagering Calculator

K2 Performance/Class Horse Race Wagering Calculator

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Usage conditions apply
This plastic circular slide rule has a white base, with three concentric logarithmic scales, all numbered from 1 to 50. The outer scale is labeled “SHOW (3rd)”; each unit has six subdivisions. The middle scale is labeled “PLACE (2nd)”; each unit has three subdivisions. The innermost scale is labeled “RACES WON”; units are not subdivided. There is a clear plastic hairline indicator.
A smaller gold disc lies atop the white one. It is pivoted at the center and has a logarithmic scale, running from 1 to 95 and marked: TOTAL RACES ENTERED. Two more logarithmic scales are visible through a window in the gold disc. These provide the total purses of the races the animal had entered and, finally, the performance-class factor rating. According to the donor, if F=number of first place finishes of a horse, S=number of seconds, T = number of thirds, R = number of races entered, and M= the total money won, the scale calculates the number [[100F + 33.333S + 16.666T]/R] + 1.12 M.
The gold disc is marked: K2 (/) PERFORMANCE/CLASS CALCULATOR (/) COPYRIGHT 1972 K2 PUBLISHING CORP. Accompanying the calculator are a paper instruction booklet, a sheet of paper giving the formula calculated by the machine, and a computer printout showing a similar calculation. The 20-page booklet was also copyrighted in 1972 and indicates the method can be used for thoroughbred, harness, and greyhound racing. K2 Publishing Corporation was located at 475 Northern Blvd., Great Neck, N.Y., where an office building was built in 1967.
Everything is stored in a black plastic case with a clear plastic front. Another slide rule for handicapping horse races is 1998.3050.02.
Reference: Tom Wyman, "More About Slide Chart Devices," Journal of the Oughtred Society 16, no. 2 (2007): 15–18.
Currently not on view
Object Name
calculating rule with instructions
slide rule with instructions
date made
K2 Publishing Corp.
place made
United States: New York, Great Neck
Physical Description
metal (part material)
plastic (overall material)
paper (part material)
overall: 16 cm x 16 cm x.3 cm; 6 5/16 in x 6 5/16 in x 1/8 in
ID Number
nonaccession number
catalog number
Credit Line
Gift of Edward C. Klauck
Rule, Calculating
Horse Racing
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Slide Rules
Data Source
National Museum of American History
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