Editing Mechanical calculator (section)

===Prototypes and limited runs===
[[File:Arithmometer - Detail of Multiplier pre 1851.jpg|right|thumb|<div align="center">Arithmometers built from 1820 to 1851 had a one-digit multiplier/divider cursor (ivory top) is on the left. Only prototypes of these machines were built.</div>]]
* In 1820, [[Thomas de Colmar]] patented the Arithmometer. It was a true four operation machine with a one digit multiplier/divider (The [[The Millionaire (calculator)|''Millionaire'' calculator]] released 70 years later had a similar user interface<ref>A notable difference was that the Millionaire calculator used an internal mechanical product lookup table versus a repeated addition or subtraction ''until a counter was decreased down to zero and stopped the machine'' for the arithmometer</ref>). He spent the next 30 years and 300,000 Francs developing his machine.<ref>[http://www.arithmometre.org/Bibliotheque/BibNumerique/AmiDesSciences1856/AmidesSciences1856.pdf L'ami des Sciences 1856, p. 301] www.arithmometre.org (page. Retrieved 22 September 2010)</ref> This design was replaced in 1851 by the simplified arithmometer which was only an adding machine.
* From 1840, Didier Roth patented and built a few calculating machines, one of which was a direct descendant of [[Pascal's calculator]].
* In 1842, Timoleon Maurel invented the [[Arithmaurel]], based on the Arithmometer, which could multiply two numbers by simply entering their values into the machine.
* In 1845, [[Izrael Abraham Staffel]] first exhibited a machine that was able to add, subtract, divide, multiply and obtain a square root.
* Around 1854, [[Andre-Michel Guerry]] invented the Ordonnateur Statistique, a cylindrical device designed to aid in summarizing the relations among data on moral variables (crime, suicide, etc.)<ref>Larousse, P. (1886), ''Grand dictionnaire universel du XIX siècle'', Paris, entry for A-M Guerry</ref>
* In 1872, [[Frank Stephen Baldwin|Frank S. Baldwin]] in the U.S. invented a [[pinwheel calculator]].
* In 1877 [[George B. Grant]] of Boston in the United States began producing the Grant mechanical calculating machine capable of addition, subtraction, multiplication and division.<ref>[[#CYBERSPACE|Hook & Norman]] p.252 (2001): "Grant developed two models of his calculating machine: a ''Barrel model'', which he exhibited at the Centennial Exposition along with his difference engine; and a ''Rack and Pinion'' model, of which he was able to sell 125 examples.  Although Grant never made much money from his calculating machines, his experiences in designing and constructing them led him to establish the highly successful ''Grant Gear Works'', which helped to pioneer the gear-cutting industry in the United States."</ref> The machine measured 13x5x7 inches and contained eighty working pieces made of brass and tempered steel. It was first introduced to the public at the 1876 Centennial Exposition in Philadelphia.<ref>''"Improved Calculating Machine"'', "Scientific American" Vol. XXXVI, No. 19, 12 May 1877 p.294 New York: Munn &Company (Publisher)</ref>
* In 1883, Edmondson of the United Kingdom patented a circular stepped drum calculator.<ref>[http://www.ami19.org/BrevetsFrancais/1883Edmonson/1883Edmonson.pdf Patent application in French] from www.ami19.org scanned by Valéry Monnier (retrieved on 12 January 2012)</ref>

{|
| [[File:Detail of a Roth Calculating machine.png|thumb|Detail of an early calculating machine invented by Didier Roth around 1840.  This machine is a direct descendant of [[Pascal's calculator]].]]
| [[File:Grant mechanical calculating machine 1877.jpg|thumb|left|Grant's Barrel, 1877]]
|}