Pinwheel calculators were invented independently by Frank S. Baldwin in the USA (1872) and Wilgott Theophil Odhner in Russia (1874).
History
In Russia, Odhner's arithmometers were mass-manufactured first in 1886 by W.T. Odhner, Maschinenfabrik & Metallgiesserei and later in 1891 by the Odhner-Gill factory (фабрика Однера-Гиля) in St. Petersburg. Pinwheel calculators were more popular in Europe (particularly in Germany) than in the United States. In 1924, Felix Dzerzhinsky, the head of the Russian Cheka, initiated the manufacturing of arithmometers. Later they were named arithmometer Feliks and served in the Soviet Union well into the 1970s, popularly known under the name "Iron Feliks".
Operation
"The operation of machines of this type was accomplished by means of pulling levers or knobs to set up the desired number. Addition, subtraction, multiplication, and division were accomplished by means of revolving drums. For addition they revolved in one direction, and for subtraction the direction was reversed. For multiplication the revolutions were repeated in the same direction as for addition, and for division they were repeated in the same direction as for subtraction. Two sets of dials provided a means of reading totals. In one the accumulation of totals appeared; in the other, there appeared the figure which was added, subtracted, multiplied, or divided." (The Office Appliance Manual, p. 88)
