Webb Adder

This stylus-operated non-printing adding machine has two brass wheels, one considerably smaller than the other. It sits in a wooden frame. The large wheel adds sums up to 99, and the smaller one is for hundreds and thousands. The numbers 00 to 99 are stamped evenly counterclockwise around the edge of the larger wheel (these numbers are covered by the plate). Inside these is a circle with 100 holes. Inside the holes is a second set of numbers from 0 to 99, displaced by 180 degrees from the first set. The smaller wheel has the numbers from 0 to 49 stamped around it in two concentric circles, with a circle of 50 holes in between. It represents hundreds. The nickel-plated brass plate covers the outermost edges of both wheels, and is screwed to the frame. Over the edge of the larger wheel, the rim of the plate is divided counterclockwise from 0 to 99. Over the smaller wheel, the edge of the plate has marked divisions from 0 to 9. The result appears in a window between the two wheels, and may be as large as 4999. There is a hook at the left side of the instrument that could be used to suspend it.
The instrument is marked on the front: C.H.WEBB. N.Y. It is also marked there: THE ADDER PATD MARCH 10TH 1868. It has serial number A 5353 stamped on the back. The device was given to the Smithsonian in 1956 by Rudolf Schneider of Washington, D.C. A mark on the back reads: R. Schneider (/) 1885.
Charles Henry Webb (1834-1905) was a journalist, playwright, poet, and roamer. He patented a second version of this device in 1889. Rudolf Schneider (1865-1956), the donor of the object, was a German-born mechanic who came to the United States in 1882. From 1885 he worked for the D. Ballauf Manufacturing Company of Washington, D.C. Schneider became owner of the company in 1914 after the death of Mr. Ballauf. In 1944, he sold the firm to two employees, but continued to use a desk and experimental workshop. He gave the Webb adder to the Smithsonian Institution in the year of his death.
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. 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.
“R. Schneider, Proprietor of Factory,” Washington Post, September 4, 1956, p. 26.
Currently not on view
Object Name
adding machine
date made
Webb, Charles H.
Physical Description
steel (overall material)
wood (overall material)
brass, nickel-plated (overall material)
brass (overall material)
overall: 2 cm x 17.8 cm x 12.6 cm; 25/32 in x 7 in x 4 31/32 in
place made
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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