Comptograph Model 3A

This full keyboard printing manually operated adding machine has a metal case painted black, and nine columns of black and white plastic keys, colored to represent cents, dollars up to 999 dollars, thousands of dollars up to 999,0000 dollars, and millions of dollars. Complementary digits are indicated on the keys. A red button is at the base of each column of keys. In front of the keyboard is a row of nine number dials, covered with glass. At the front of the machine is a row of eight metal levers that may relate to subtraction. The total/error/normal, subtotal, and carriage lock levers are along the right of the machine, somewhat below the keyboard. A crank on the right operates the machine. The printing mechanism, wide black metal carriage, and serrated edge for tearing a paper tape are at the back. The machine is extremely heavy.
The machine is marked on the front: Comptograph (/) Co. (/) CHICAGO, U.S.A. It is marked on the back: MODEL 3A (/) PATENTED (/) NOV. 25. 1890. It is also marked there: NOV. 2. 1909. These are the first and last patent dates listed. It also is marked there: OTHER PATENTS PENDING. It is also marked there: PATTERN NO 16.
This model is from the collection of Felt & Tarrant Manufacturing Company.
Currently not on view
Object Name
adding machine
date made
Comptograph Company
Physical Description
iron (overall material)
plastic (overall material)
steel (overall material)
glass (overall material)
overall: 34 cm x 49 cm x 47.5 cm; 13 3/8 in x 19 9/32 in x 18 11/16 in
place made
United States: Illinois, Chicago
ID Number
catalog number
accession number
Science & Mathematics
Adding Machines
See more items in
Medicine and Science: Mathematics
Adding Machines
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Victor Comptometer Corporation
Additional Media

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