Mathematical Table, Young Rule For Calculating Interest

This United States patent model has a rectangular wooden frame with five grooves, each of which holds a bar (made from a different kind of wood) that slides crosswise. Two flat wooden pieces cover much of the bars on the left side, with a gap between them. Each bar has a set of 12 evenly spaced holes that are numbered from 11 down to 1 (the “0” holes are not numbered). Each bar also is indented at the top to hold a slip of paper that slides under the top of the machine. There are 11 further, unnumbered, holes to the right of each slip of paper. Setting up a number on the rods (to represent an amount of money or a length of time) reveals a number on the paper slips that represents an amount of tax or interest.
A piece of paper glued to the top of the device reads: S.S. Young’s Tax and (/) Interest Rule (/) Red March 18th 1851. The “d” in this mark is a superscript.
Samuel S.Young of Eaton, Ohio, took out three patents for computing devices. This is the patent model for the second, a rule for calculating interest, patented September 2, 1851 (U.S. Patent 8323). The first was an add to addition or adder, patented July 24, 1849 (U.S. Patent 6602), the third an arithmetical proof rule, patented October 26, 1858 (U.S. Patent 21921). The U.S. Census for 1850 lists an S. S. Young of Eaton, Ohio, who was forty years old that year and living with his wife and two children. His occupation is given as “gardener.” Apparently by 1860 he had moved to the nearby town of Washington and is listed as being a “horticulturalist” by profession. Young assigned his patent to John R. Stephen of Eaton, who is listed in the 1860 Census as a farmer.
Compare to the model for the first of his inventions, MA*252680.
S. S. Young, “Rules for Calculating Interest,” U.S. Patent 8329, September, 1851.
U. S. Census Records
Robert Otnes, “Sliding Bar Calculators,” ETCetera, #11, June, 1990, p. 6.
P. A. Kidwell, “Adders Made and Used in the United States,” Rittenhouse, May, 1994, p. 80.
Currently not on view
Object Name
mathematical table
date made
Young, Samuel S.
Young, Samuel S.
Physical Description
wood (overall material)
paper (overall material)
overall: .8 cm x 35.4 cm x 4.1 cm; 5/16 in x 13 15/16 in x 1 5/8 in
place made
United States: Ohio, Eaton
place patented
United States: Ohio, Eaton
ID Number
catalog number
accession number
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Mathematical Charts and Tables
Data Source
National Museum of American History, Kenneth E. Behring Center


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