Webb Adder

This is a two-wheeled steel and nickel-plated brass adding machine. It is stylus-operated and non-printing. The large wheel has 00 to 99 stamped around the edge. The smaller wheel has 0 to 49 stamped around its edge. A ring of holes is inside each ring of numbers. A metal plate covers the outer edges of the two wheels, revealing sums in a small window between them. The numbers 0 to 99 also are stamped around the window for the larger wheel. Numbers are added by rotating the wheels, up to sums of 4999. The carry mechanism is that patented by L. C. Smith (patent 414335). The frame is serrated around the edge, and smooth on the back. A metal piece is attached to the frame at the top. There is a stylus. The machine is marked: “THE ADDER.” It has serial number 549. There are no references to any patent numbers on the device, nor is Webb mentioned. The example comes from the Draper family of New York.
C. H. Webb, “Adding-Machine,” U.S. Patent 414959, November 12, 1889.
Lester C. Smith, “Adding-Machine,” U.S. Patent 414335, November 5, 1889.
P. A. Kidwell, “The Webb Adder,” Rittenhouse, 1 (1986), pp.12-18.
E. Martin, The Calculating Machines (Die Rechenmaschinen), trans. P. A. Kidwell and M. R. Williams, Cambridge: MIT Press, 1992, p. 63.
Currently not on view
Object Name
adding machine
date made
ca 1890
Webb, Charles H.
Physical Description
brass, nickel-plated (overall material)
steel (overall material)
overall: .7 cm x 16.2 cm x 12.5 cm; 9/32 in x 6 3/8 in x 4 29/32 in
place made
United States: New York, New York
place patented
United States: New York, New York
ID Number
accession number
catalog 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 John William Christopher Draper and James Christopher Draper
Additional Media

Visitor Comments

Add a comment about this object

**Please read before submitting the form**

Have a comment or question about this object to share with the community? Please use the form below. Selected comments will appear on this page and may receive a museum response (but we can't promise). Please note that we generally cannot answer questions about the history, rarity, or value of your personal artifacts.

Have a question about anything else, or would you prefer a personal response? Please visit our FAQ or contact page.

Personal information will not be shared or result in unsolicited e-mail. See our privacy policy.

Enter the characters shown in the image.