Slate with Numeral Frame

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This object combines two common tools of 19th-century American teaching: the slate and the teaching abacus or numeral frame. Both the piece of black slate and the wires of the numeral frame fit in a wooden framework. There are two rows of wooden beads, with ten beads in each row. The beads are painted in the colors of the spectrum (red, orange, yellow, green, blue). The unsigned and undated instrument was given to the Museum in 1975.
In the 1870s and 1880s, at least three Americans took out patents for combination slates and abaci. Freeman D’Ossone of Philadelphia proposed a slate with a row of nine numbered beads that moved up and down on a wire in a frame with the slate (US Patent 119,332, dated September 26, 1871). The beads shown in the patent description are spherical.
Henry Stewart of Erie, Pa., proposed an abacus attachment for school slates that fit atop the slate and had two rows of beads with ten beads in each row. The beads are slightly flattened (US Patent 217,749, dated February 6, 1883).
Charlotte Francis Roddey of New York City proposed an “abacus for slates” in which a single row of 25 spherical beads fit into the frame of an abacus (US Patent 339933, dated April 13, 1886). None of these inventions precisely matches this object. It seems likely, however, that this slate with numeral frame dates from about the same period.
Currently not on view
date made
ca 1890
Physical Description
wood (overall material)
metal (overall material)
slate (overall material)
overall: .1 cm x 22.3 cm x 22.3 cm; 1/32 in x 8 25/32 in x 8 25/32 in
ID Number
catalog number
accession number
Credit Line
Gift of Edith R. Meggers
See more items in
Medicine and Science: Mathematics
Learning Arithmetic
Arithmetic Teaching
Science & Mathematics
Data Source
National Museum of American History


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