Inventor of one of the most popular portable mechanical calculators the Arithmometer
Royal Institute of Technology Stockholm
Historical Pioneer (Pre-Moderns)
Although calculating machines were quite rare in Russia in those times, it is commonly thought that Odhner must have seen (possibly brought in for some repair) or have read about the Thomas de Colmar arithmometer which was designed in 1822. He thought that he could design a better and more efficient calculating machine. His solution was based on a geared pinwheel mechanism and resulted in the well-known barrel-shaped calculating machines bearing his name. It was ready for demonstration in 1875. In 1878 he submitted an application for the patent on his invention to the United States Patent Office which was awarded three months later; this was soon followed by patents in other countries. From Odhner’s correspondence we know that he saw his new invention as the solution to his permanent shortage of finances. Fortunately Nobel saw the merit of the Odhner machine and asked him to produce 14 machines. He also gave Odhner some space in his factory for the manufacture of these machines and he agreed to carry the costs as well as paying Odhner a salary. The two men agreed they would later split the profits of this endeavour. Although the first model carried only 9-digit results, the next version could handle 10-digit answers and this increased to 11 digits by 1889. The machine had three registers: one to manually set the multiplicand, one to register the result and one to count the revolutions of the crank (i.e. the multiplier). For each manual revolution of the crank the multiplicand would be added to the results register, while the revolution register kept track of the number of revolutions. After having done one decimal position the carriage was shifted one position to the left for the next decimal. Clearing of the registers took place through the use of wing-nuts on either side of the carriage on earlier models, clearly visible in above illustration. In later models the wing-nuts were replaced by crank handles.
Courtesy of Wikipedia