Patent Model Adder by Milton W. Hinkle

This patent model for an adder has wooden sides and a brass strip that covers the front, bottom, and back. The top of the instrument is curved at the front to the shape of two wheels that rotate inside it. A strip of wood between the wheels has the digits from 1 to 9 marked on it. Each wheel has the digits from 0 to 9 marked on it three times. A pin protrudes from the wheel between each digit, and each tenth pin is slightly longer than the others. The spacing of the digits is the same as that on the case. The large wheels are linked to two smaller toothed wheels at the back of the instrument. These wheels are marked with the numbers from 0 to 13, and are meant to move forward every time the large wheel passes a “10” pin, recording numbers that should be carried. There are no separate wheels for registering results.
A mark on the right side reads: Milton W. Hinkle (/)] INVENTOR (/) Memphis Tenn (/) 1877. Another mark there reads: 27-101.
Compare to Burns addometer (MA*308911) and Ballou adding machine (MA*309323).
There was a Milton Washington Hinkle Jr., born January 8, 1848, in Carrollton, Carroll County, Kentucky, with parents Jacob and Nancy Kennedy Hinkle. Whether this is the same Milton Washington Hinkle is unclear.
This machine was once in the collection of L. Leland Locke and was exhibited at the Museums of the Peaceful Arts in New York City.
References: U.S. Patent 200911, January 11, 1878. Munn & Co. attorneys for patent.
William Sumner Junkin, Minnie Wyatt Junkin, The Henckel genealogy. . ., New Market, Va., Henckel Family Association, 1964, p. 109.
Currently not on view
Object Name
date made
Hinkle, Milton W.
Hinkle, Milton W.
Physical Description
wood (overall material)
brass (overall material)
overall: 9.6 cm x 3 cm x 13.5 cm; 3 25/32 in x 1 3/16 in x 5 5/16 in
place made
United States: Tennessee, Memphis
place patented
United States: Tennessee, Memphis
ID Number
accession number
catalog number
Science & Mathematics
See more items in
Medicine and Science: Mathematics
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of L. Leland Locke
Additional Media

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