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.

Date Made: ca 1890

Patentee: Webb, Charles H.

Location: Currently not on view

Place Made: United States: New York, New York CityPlace Patented: United States: New York, New York City

Subject: Mathematics


See more items in: Medicine and Science: Mathematics, Adding Machines, Science & Mathematics


Exhibition Location:

Credit Line: Gift of Mrs. Chauncey B. Schmeltzer

Data Source: National Museum of American History

Id Number: MA.317925.01Accession Number: 317925Catalog Number: 317925.01

Object Name: adding machineOther Terms: adding machine; Stylus Operated, Non-Listing

Physical Description: brass, nickel-plated (overall material)steel (overall material)Measurements: overall: .7 cm x 16.1 cm x 11.1 cm; 9/32 in x 6 11/32 in x 4 3/8 in

Guid: http://n2t.net/ark:/65665/ng49ca746a5-008c-704b-e053-15f76fa0b4fa

Record Id: nmah_690283

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