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New acquisition: A circular slide rule called an “omnimetre,” invented in 1891
As its name suggests, the omnimetre was designed to carry out numerous operations of arithmetic and trigonometry, says Peggy Kidwell, curator of mathematics at the Smithsonian. “It has scales for multiplication, division and common logarithms, as well as squares, cubes, and fifth powers of numbers.” In his own words, Sexton called his circular invention a “quite useful and inexpensive slide rule.” [...more]
