Webb Adder

This two-wheeled stylus-operated non-printing adding machine is in a wooden frame. The large brass wheel has a ring of holes and the numbers 00 to 99 stamped around the edge. The numbers 0 to 99 also are stamped around the window for the larger wheel. Numbers are added by rotation of the wheels. Answers are recorded on a pedometer-like dial that has separate windows for ones, tens, hundreds, and thousands. The frame is screwed to the cover plate. There is a stylus. The large wheel is marked: C.H.WEBB. N.Y. It is also marked: “THE ADDER" PATD MARCH 10TH 1868. The back has the serial number: C1053. The dial is a modification of the instrument. It is marked on paper attached over the small wheel: N.Y.STANDARD WATCH COMPANY.
Charles Henry Webb (1834-1905) was a journalist, playwright, poet, and roamer. He patented a second version of this device in 1889. This example was owned by the Draper family of New York.
C. H. Webb, “Improvement in Adding Machines,” U.S. Patent 75322, March 10, 1868.
“Machine for Addition,” Journal of the Franklin Institute, 60 (1870): pp. 8-9.
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
date made
Webb, Charles H.
Webb, Charles H.
place made
United States: New York, New York
place patented
United States: New York, New York
Physical Description
glass (overall material)
brass (overall material)
brass, nickel-plated (overall material)
paper (overall material)
wood (overall material)
overall: 2.5 cm x 17.3 cm x 12.2 cm; 31/32 in x 6 13/16 in x 4 13/16 in
ID Number
accession number
catalog number
Credit Line
Gift of John William Christopher Draper and James Christopher Draper
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Adding Machines
Data Source
National Museum of American History


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