Wales Model 10 Series Adding Machine

This full keyboard manually operated printing adding machine has a metal frame painted black, with glass sides and front, and a glass panel in front of the number dials. There are nine columns of plastic keys, with the keys colored according to the place value of the digit represented by the column. The keyboard is covered with green felt. To the left of the keyboard is total key, above the number keys are red plastic repeat and error keys, and behind the numeral dials are non-print and non-add keys. These nine dials are behind the keyboard, with divisions for U.S. currency indicated.
The metal crank for operating the machine is on the right. At the back of the machine is the printing mechanism and a 13-inch (33 cm.) movable carriage. The machine is extremely heavy. The case must be removed to replace the ribbon.
The machine is marked on the front: WALES. It is marked above the keyboard: WALES (/) Visible (/) Adding (/) and Listing (/) Machine (/) THE ADDER MACHINE COMPANY (/) WILKES-BARRE, PA.,U.S.A.. It is marked on a list of 17 patents on the back of the machine with the first patent date: DEC. 1. 1903. The last patent date given there is: NOV. 23. 1909.
The Wales adding machine is based on patents of the inventor Charles Wales, a native of Maryland who had a long career as an inventor of adding machines. He first applied for an adding machine patent in 1902 as a resident of Detroit. By 1903, he was assigning his patents to the Adder Machine Company. That company moved manufacture from Detroit to Pennsylvania in 1906. From the first, Wales was interested in designing machines in which the results of computations were visible to the operator (this was not true on Burroughs adding machines of the time). Wales adding machines featured visible printing of results. Wales soon left the company that bore his name to work for Burroughs, and patented a visible printing mechanism used in their machines. He later designed the Federal adding machine, which was manufactured by the Colt Fire Arms Manufacturing Company of Hartford.
This Wales adding machine is from the collection of Felt & Tarrant Manufacturing Company, a rival firm of Wales.
J. H. McCarthy, The American Digest of Business Machines, Chicago: American Exchange Service, 1924, pp. 544-545.
Currently not on view
date made
Adder Machine Company
place made
United States: Pennsylvania, Wilkes-Barre
Physical Description
plastic (overall material)
rubber (overall material)
glass (overall material)
metal (overall material)
felt (overall material)
overall: 27 cm x 42 cm x 58 cm; 10 5/8 in x 16 17/32 in x 22 27/32 in
ID Number
accession number
catalog number
Credit Line
Gift of Victor Comptometer Corporation
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Adding Machines
Data Source
National Museum of American History


I have a Universal Adder that has all metal sides. The only glass is in the window where the register numbers are showing. The cover lifts straight up off of four pins in the bottom frame. You have to remove the ribbon cartridge first and you may have to remove three pushbuttons on the left hand side to clear them.
Does anyone know how to lift the cover to clean the inside of the machine?

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