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.

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 John William Christopher Draper and James Christopher Draper

Data Source: National Museum of American History

Id Number: MA.335358Accession Number: 304826Catalog Number: 335358

Object Name: adding machine

Physical Description: brass, nickel-plated (overall material)steel (overall material)Measurements: overall: .7 cm x 16.2 cm x 12.5 cm; 9/32 in x 6 3/8 in x 4 29/32 in

Guid: http://n2t.net/ark:/65665/ng49ca746a4-f526-704b-e053-15f76fa0b4fa

Record Id: nmah_690286

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