Rotating Multiplication Table

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This device is a rotating multiplication table, probably intended as a currency converter.
The wooden box contains a cylinder that is rotated by turning a metal wheel on the left side. A lid at the front of the box opens to reveal a paper strip with a horizontal row of numbers pasted to the box, a window below that shows a row of numbers on a paper pasted to the cylinder, and a paper strip with three horizontal rows of numbers pasted to the box below the window. The leftmost number on the cylinder increases as it is turned from 1 to 30. Numbers on the row of numbers above this window increase from 2 to 11, including intermittent values such as 2/3, 2/6, and 2/9.
Supposing that these numbers are in feet and inches, the product shown on the cylinder is given in fathoms [1 fathom = 6 feet = 72 inches]. Supposing that these numbers are in Massachusetts shillings and pence (6 shilling = $1 in 1818), the tables give the dollar and cents equivalents of multiples of Massachusetts currency.
The three rows of numbers below the window are labeled 1/4, 1/2, and 3/4. They give fractional values of the numbers in the top row, in the converted units (e.g. if the numbers in the top row represent shillings, they give values of fractions of that number of shillings, in cents).
The device is marked faintly in pencil on the bottom. This mark reads in part: May 1814.
According to the Ethnology catalog card, this object is American. It came with a large collection of Americana, particularly with school apparatus from New England.
Compare MA.328416.
Zacariah Jess, The American Tutor’s Assistant, Philadelphia, 1818, p. 18.
Currently not on view
date made
Physical Description
wood (overall material)
metal (overall material)
paper (overall material)
overall: 9 cm x 43 cm x 13 cm; 3 17/32 in x 16 15/16 in x 5 1/8 in
ID Number
catalog number
accession number
Credit Line
Gift of Dr. and Mrs. Arthur M. Greenwood
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Mathematical Charts and Tables
Data Source
National Museum of American History


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