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24 July 2021

Inventor, self-taught mathematician.

Girsh Ioffe was a self-taught mathematician from the town of Petrovichy, Klimovichy district, Mogilev province.

All counting devices that appeared in the middle of the XIX century were the intermediary between the abacus and computing machines. In Russia, in addition to the device of Slonimsky and modifications of the Kummer arithmetical device, the so-called counting bars invented in 1881 by Ioffe were quite popular; the latter were made up the same as the Slonimsky cylinders.

The idea of this device was taken up from the “Napier sticks” known from the XVI century – the counting instrument proposed by the Scottish mathematician, the inventor of logarithms John Napier.

Their working principle is based on the Slonimsky theorem. The Ioffe device consisted of 70 tetrahedral bars placed in a special box. This mechanism allowed quick performance of four arithmetic functions. This, in turn, made it possible to place 280 columns of the Slonimsky table on 280 faces. Each bar and each column was labeled, for which the Arabic and Roman numbers and the Latin alphabet were used. Latin letters and Roman numbers served to indicate the order in which it was necessary to place bars to get a product of the multipliers. The obtained products (and their number equals to that of discharges in the multiplier) were added (in the same way, as if using a counting device of Slonimsky) with a pencil and paper. Although it was not quite convenient, but in the XIX century people reasoned otherwise. There were almost no effective and reliable arithmometers (the mass production of Odhner-machines began in the 90s), and such a prominent author as Bool comes to the following conclusion in 1896: “Bars used by Ioffe simplify the multiplication of numbers even more than Napier sticks and their modifications. After simple bars of Luke and Janoy this is the best arithmetic device for multiplication”.
The invention of G.Ioffe was shown at the All-Russian exhibitions in 1882 (honorary review) and 1896. In Nizhniy Novgorod “Support Tools for Scientific Goals” by G.Ioffe were demonstrated in the class “Precision Tools for Scientific Goals”.

Sourced from the database of the Republican Library on Science and Technology.