Leavitt Calculating Disc

Printed tables have long offered bankers, businesspeople, and customers a way to calculate interest. This example consists of two interest tables, printed on paper, arranged radially and pasted to the two sides of a pine disc. A slotted piece pivoted at the center of the disc rotates, so that one can select the appropriate column of the tables. The first table gives the interest on sums ranging from 2 cents to $1,000 at a rate of 6 percent, for periods of from 1 to 7 days, 1 to 11 months, and 1 year. The second table gives the total value of an amount compounded at 6% annually for periods of 1 to 6 years.

A mark on the front and the back reads: Entered according to act of Congress, in the Year 1845, by Wm. B. LEAVITT, in the Clerk’s Office of the District Court of New Hampshire. A mark on the front reads: Stereotyped by Morrill, Silsby & Co.

William B Leavitt is probably the astronomer and almanac author William B. Leavitt (1812–1895) of North Grantham, New Hampshire. He studied with his uncle, Dudley Leavitt, and took over Dudley’s popular almanac when he died in 1851. William B. Leavitt carried out the calculations for Leavitt’s Almanac until his own death.

Reference:

“Life Sketches of Leading Citizens of Merrimack and Sullivan Counties, New Hampshire,” Biographical Review vol. 22, Boston: Biographical Review Publishing Company, 1897, p. 475.

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