Stephenson's Adding Machine
Archibald M. Stephenson (1844-1913) of Manteno, Illinois, took out a US patent №137167 for Adding Machine on March 25, 1873 (see the lower patent drawing). Despite its very simple construction and operation, the Stephenson's adder was perhaps actively being sold as late as 1929, a period of 56 years!
The patent drawing Stephenson's adding machine
The original Stephenson's Adding Machine is a four-wheeled stylus-operated adding machine with a rectangular wooden base and an automatic carry, made by wood, paper and brass. Measurements: 2 cm x 26.6 cm x 9 cm.
Four adjacent rotating wheels are inset in the wooden base, with a metal cover that fits over them. The three small wheels on the right each have a metal arm pivoted at their centers and ten evenly spaced indentations around the edge. The digits from 0 to 9 are marked on the cover just outside each of these wheels. The numbers increase counterclockwise going around the first and third wheels and clockwise going around the second wheel. The two middle wheels also have ten pins arranged just inside the indentations. The pins of one wheel are linked to the arm of the wheel to the right of it. The fourth, leftmost, wheel is larger and has 20 indentations and 20 pins. The indentations are numbered from 0 to 19 going counterclockwise. There are no detents shown, which could make the actions erratic.
The patent model of Stephenson's adding machine (© Smithsonian Institution)
Stephenson probably never made any adders of the original design (besides the patent model). For the production devices he modified it heavily, reducing the number of dials to only two, and adding a single detent (to stop the leftmost wheel from turning further than one position when the tooth from the rightmost wheel engages it).
The two-wheeled versions were sold at least up to the end of 1920s under a number of different names (Perfection Adding Machine, Universal Adding Machine, Mindling Vest Pocket Adding Machine, etc.), made by different manufacturers (including the Stephenson's own workshop in Joliet, Illinois), which are sold in the end of 19th and the beginning of 20th century for $1-$2.
In the two-wheeled production version (see the lower photo), the user may enter only single digits in the right wheel. There is also an automatic carry to the left wheel, which registers up to 19, so that the maximum sum is 199. The Stephenson's adder seems to have been an aid for people adding long columns of figures using paper and pencil.
The two-wheeled version of Stephenson's Adding Machine
The device is only 3.5 inches long, 2-3 mm thickness, and is constructed entirely of brass. Numbers are entered by means of a pen. Reverse turn (i.e. subtraction) is not possible. Reset is done by manual forward rotation to 0.
Who was Archibald Stephenson—the inventor of this super-simple adder?
Archibald Stephenson was born on June 2, 1844, near a creek called Brown's Wonder near Lebanon, Indiana, northwest of Indianapolis.
In 1860 his family moved to Tolono, Illinois. In 1863 Stephenson started his career as an agent of Illinois Central Railroad at Peotone, Illinois. Later, he became a clerk. In 1865 he became a travelling salesman and left Illinois, making a complete tour of the US, visiting every state and territory.
Upon returning to Illinois, he established in Beardston and became an agent of Rockford, Rock Island & St. Louis Railroad, meanwhile performing several tours as a travelling salesman.
In 1879 Stephenson left the railroad business and was engaged in newspaper business, which he left in 1892, making another trip, covering every US state and territory.
In 1895 Stephenson setup in Joliet, starting work as a printer, then as a solicitor and again as a travelling agent. In 1906 he established his own printing company.
Stephenson had a wife and 3 children (two daughters and a son, who died early). He belonged to a Masonic Lodge, and was a passionate republican.
Archibald Stephenson died on September 13, 1913, of a stroke at St. Luke's Hospital, Utica, New York, while on one of his selling trips as the representative of an adding machine company, and was buried in Oakwood Cemetery, Joliet.