Chaim Zelig Slonimski, also known as Hayyim Selig Slonimski, was born on March 10, 1810, in Bialystok, Poland (then Russia), and died on May 15, 1905, in Warsaw. He was a deeply knowledgeable Talmudist and a self-taught mathematician. First in history, he began writing and publishing science books in Hebrew to enlighten the Jewish population in Eastern Europe. He introduced to Hebrew entire vocabulary of technical terms created partly by himself. Later in life, he started publishing a popular science magazine, Hazefirah, 1862, also in Hebrew, which continued after his death, till 1931. He invented several devices and processes of various sorts, including calculating machines. For his inventions, Slonimski was highly respected among well known scientists, such as Wilhelm Bessel, Viktor Bunyakovsky, Karl Gustav Jacobi, and Alexander von Humboldt, whose biography Slonimski wrote himself . He was a son-in-law of another inventor of calculating machines, Abraham Stern, marrying his daughter Sara, in 1842.
Major Contribution: Invention of a multiplication machine (1840) .
How was the machine built and how it operated? Initially, two machines were invented by Slonimski, one for addition and subtraction, and another for multiplication. The one for multiplication was based on a newly discovered theorem from number theory, called the Slonimski Theorem. The operation of the multiplication machine, which is more important, has been described by Slonimski himself in Russian , and in several secondary sources [4-7]. In principle, it was an implementation of multiplication tables, which resulted from application of the Theorem. Since the amount of related numbers was not that large, they were put on the cylinders, which – when moved appropriately – were showing the multiplication results in small windows. Since the original Slonimski source material  is not easily available, we recommend his brief description published in , available at this webpage in Resources.
What exactly was the Slonimski Theorem? This is the Theorem, on which the multiplication machine was based. It turns out that Slonimski did not seem to have published the Theorem at all. He presented it to the St. Petersburg Academy, where it was recorded in the minutes . Moreover, he never proved it himself. However, it is interesting that a German mathematician August Leopold Crelle, who was familiar with the Theorem from Slonimski’s personal communication during his visit to Berlin in 1844, and later published Slonimski’s paper on his machine , took time and proved Slonimski’s Theorem and published the result in his own journal .
Slonimski’s machine got high recognition during his life time. On August 8, 1844  he demonstrated his devices to the Royal Prussian Academy of Sciences. Next year, on April 4, 1845, he presented the machine to the Academy of Sciences in St. Petersburg , and obtained their recommendation for the Demidov Prize, which was awarded to him on June 24, 1845. He was granted patent for this machine on November 24, 1845, for the period of ten years . He also applied for patents in the U.S. and Britain, but apparently unsuccessfully [12-13]. Remarkably, Slonimski’s Theorem was used already a few years after its publication . Slonimski’s most lasting contribution was probably his dedication to the popularization of science in the Jewish culture.
The historical contribution of this project is in finding the source material on Slonimski, which has been published in at least six different languages (English, German, French, Russian, Polish, and Yiddish), organizing it, and making it available – in part – on this website. This includes, in particular, the details of Slonimski’s theorem [9-10] and his patent applications [12-13]. This should form the basis for a more in-depth study by a serious researcher to give some more attention to this incredible inventor. However, one extremely interesting fact has to be noted, more relevant to the history of communications than computing, that Slonimski also invented quadruplex transmission, and published the results in 1859 .
 Ch.Z. Slonimski, Alexander von Humboldt. Eine biografische Skizze. Verlag von Veit & Comp., Berlin, 1858
 M.I. Radovskii, Izobratel arifmeticheskoi mashiny Z.Ja. Slonimskii, Vestnik Akademii Nauk SSSR, Vol. 10, pp. 115-120, 1952
 Z. Slonimskii, Opisanie novogo chislennogo instrumenta, izobretennogo Z. Slonimskim, St. Petersburg, 1845
 I.A. Apokin, The Slonimski Theorem and Its Implementation in Simple Multiplication Devices, pp. 29-31, Computing in Russia, G. Trogemann, W. Ernst, A.Y. Nitussov (Eds.), Vieweg, 2002
 I.A. Apokin, L.E. Maystrov, Razvitsiye vychislitelnykh mashin, Nauka, Moskva, 1974 (Slonimski’s machine, pp. 93-98)
 I.A. Apokin, L.E. Maystrov, Istoria vychislitelnoi tekhniki, Nauka, Moskva, 1990 (Section 2.6. Teoriema Slonimskogo i prostyie mnozhitelnyie ustroistva na eio osnovie)
 Selig Slonimski und sein Recheninstrument, Illustrierte Zeitung, Vol. 5, No. 110, pp. 90-92, 1845
 Ch.Z. Slonimsky, Allgemeine Bemerkungen über Rechenmaschinen und Prospectus eines neu erfundenen Rechen-Instrumente, Journal für die reine und angewandte Mathematik, Vol. 30, pp. 215-229, 1846
 M.I. Radovskii, E. Kolman, Iz istorii vychislitelnykh ustroistv (po materialam arkhiva AN SSSR), Istoriko-matematicheskie issledovania, Vol. 14, pp. 551-585, 1961
 A.L. Crelle, Démonstration d’un théorème de Mr. Slonimsky sur le nombres, avec une application de ce théorème au calcul de chiffres, Journal für die reine und angewandte Mathematik, Vol. 28, pp. 184-190, 1844
 K. Zielnica, Chaim Selig Slonimski und Alexander von Humboldt, Acta historica Leopoldina, Vol. 27, pp. 123-141, 1997
 J. Shatzky, Chaim Zelig Slonimski: Unknown Attempt tp takeout a patent on a Calculating Machine in Washington (in Yiddish), YIVO Bleter – Journal of the Yiddish Scientific Institute, Vol. 38, pp. 342-343, 1954
 Slonimski Patent Application Letters in the USA and Britain, YIVO Bleter – Journal of the Yiddish Scientific Institute, Vol. 38, pp. 343-344, 1954
 H. Knight, Multiplication Tablets Derived from a Theorem of S. Slonimski, Birmingham, 1847
 H. Nussbaum, Ch.Z. Slonimski (in Polish), Izraelita, Vol. 19, No. 16, pp. 127-129 April 13, 1884 (Part 1); No. 17, pp. 136-137, April 20, 1884 (Part 2).
 Ch.Z. Slonimsky, Eine allgemeine Formel für die gesammte jüdische Kalenderberechnung, , Journal für die reine und angewandte Mathematik, Vol. 30, pp. 179-183, 1846
 M. Detlefsen, Polnische Rechenmaschinenerfinder des 19. Jahrhunderts, Wissenschaft und Fortschritt, Vol. 26, No. 2, pp. 86-90, 1976
 Z. Slonimski, Opisaniye sposoba peredachi dvukh razlichnych depesh v tozhe samoe vremia priema dvukh drugikh depesh (in Russian: A Description of a Means of Transmission of Two Different Telegrams at the Same Time of Receiving Two Other Telegrams), M.O. Wolff, St. Petersburg, 1859.