Willgodt Theophil Odhner (1845~1905) Odhner sold his patent rights to Grimme, Natalis & Co. A.G. only for sale in Germany and some neighboring countries and produced himself Original Odhner calculators in St. Petersburg, Russia. Most of them remained in Russia are not too common now. After the Russian revolution the children of Odhner moved the production to a Göteborg, Sweden.

Who was Leon Bollee? Leon Bollee (1870~1913) was French inventor of the first calculating machine. Leon Bollee who was a son of the most important pioneer of steam road vehicles in France; Amedee Bollee pere. Here is the German Patent 82963 awarded to Leon Bollee in 1895. Leon Bollee in Le Mans (Frankreich) Rechenmaschine. Bollee’s machine was one of the earliest of its type and was a direct multiplier with a built-in multiplication table.

The Millionaire Calculator was designed by a Frenchman, Leon Bollee, in 1892 and a German Patent was granted in 1895. 4 Years after a machine is introduced by a Swiss Otto Steiger and built by Hans W. Egli of Zurich, from 1899 to 1935, the “Millionaire” was the first machine capable of direct multiplication. Previous to this, multiplication had been accomplished by successive additions. The Millionaire did away with this repetitive operation and could multiply two numbers with a single turn of the crank.

G. Charpentier of France The Calculimetre was invented in 1890 by G. Charpentier of France and made by H.Morin, 11 Rue Dulong, 75017 Paris France. The Calculimetre, a metal circular slide rule, about 60mm in diameter. Circular Slide Rule

William S. Burroughs (1857~1898) William S. Burroughs, of St. Louis, got his idea of building a calculator while working with Frank Stephen Baldwin, another inventor of calculating machines. He patents an adding machine. He started the construction in 1882; he resigned from a bank were he worked at that time in order to be able to fully dedicate his time towards the development of the adding machine. He invents a machine similar to Felt’s but more robust, and this is the one that really starts the office calculator industry.

Dorr Eugene Felt (1862~1930) This was the original rough model that Dorr Eugene Felt created over the year end holidays in 1884. It was a remarkable implementation of a conjoured design that simply “all came together” at a certain critical point. The Comptometer was the first practical key-driven calculator with sufficient speed and reliability to bring significant economic benefits to the processing of business data. Prior key-driven design efforts had failed to solve the twin problems of over rotation (tendency of a dial to spin past its intended stop) and carry (incrementation of the next higher order on overflow).

In 1878 Ramón Silvestre Verea García,, a Spaniard living in New York, patented a direct-multiplying machine. Verea received a U.S. patent No 207918 for the machine. He manufactured two prototypes, one of them sent together with the patent application to the US Patent Office and another one was exposed and won a medal of the World Inventions Exhibition in Matanzas, Cuba. RAMON VEREA Adding Machine

Victor Mayer Amedee Mannheim (1831~1906) Although slide rules existed before Mannheim’s time, invented by Oughtred and Gunter and others, it was Mannheim who standardised the modern version of the slide rule which was in common use until pocket calculators took over a few years ago. It was while he was a student at Metz that the ideas for this slide rule came to Mannheim. The modern standard Mannheim-type rule typically has scales that allow you to perform multiplication, division, squares, square roots, logs, sine, cosine, and tangent calculations.