Webb Adder

This two-wheeled stylus-operated non-printing adding machine is made of silver-colored metal. It has one large wheel with the numbers from 00 to 99 stamped around the edge. The second, smaller wheel has the numbers from 0 to 49 stamped evenly around its edge. A ring of holes is just inside each ring of numbers. A metal frame and plate cover the back and outer edges of the two wheels, revealing numbers in a small window between the wheels. Numbers are added by rotation of the wheels, up to sums of 4999. The frame is serrated around the edge. There is no stylus. The large wheel is marked: The Adder (/) C.H. WEBB. The plate is marked: PAT’D NOV 5TH 12TH 1889. The serial number stamped on the back is: 5136.
Charles Henry Webb of New York first patented an adding machine in 1868. This improved version of the device is described in a patent he took out on November 12, 1889, and in one obtained by Lester C. Smith on November 5 of that year. This example was used by the civil engineer Chauncey B. Schmeltzer who taught at the University of Illinois.
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. Kidwell, “The Webb Adder,” Rittenhouse, 1 (1986) 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 16.1 cm x 11.1 cm; 9/32 in x 6 11/32 in x 4 3/8 in
place made
United States: New York, New York
place patented
United States: New York, New York
ID Number
accession number
catalog number
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Adding Machines
Data Source
National Museum of American History, Kenneth E. Behring Center


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