C.W. Hergenroeder Adding Machine

This U.S. Patent Office model for an adder has a wooden frame with a round brass top and mechanism. A toothed disc under the top has the digits from 0 to 99 indicated on it in ink. The 99 complement also is indicated, for use in subtraction. To the right of the disc is a series of pins labeled from 1 to 10. An arm extending from the right side of the disc fits between the pins. Pulling the arm forward advances the disc by the amount indicated on the scale. When the disc has advanced a full rotation, it advances a smaller, vertically mounted disc on the left side by one unit. Complementary units are also indicated on the edge of this disc. The device also has a set of nine wooden digit wheels, with paper around the edge, at the front. These are intended for keeping track of numbers used in calculations.
According to the 1900 U.S. Census, Christian W. Hergenroeder was then 36 years old and living in Baltimore. He was born in Germany of German parents, immigrated to the United States in 1882, and was a naturalized citizen. His wife, Sofia, was born August of 1866, also in Germany of German parents, and came to the United States in 1891. She apparently was not naturalized. Their son, Christian Jr., was born November of 1895. Both parents could read, write, and speak English. Christian's occupation was given as laborer. The family lived in a rented house. Hergenroeder was not found in 1880, 1910, 1920 or 1930 U.S. Census records.
Another patent was granted to Christian W. Hergenroeder of Baltimore, for an improvement in music leaf turners. He applied for this patent on January 5, 1882, and was granted it on October 10, 1882 (#265602).
Reference: U.S. Patent No. 263904, September 5, 1882.
Currently not on view
Object Name
adder with carry
date made
Hergenroeder, Christian W.
Hergenroeder, Christian W.
Physical Description
wood (overall material)
brass (overall material)
paper (overall material)
overall: 5 cm x 31 cm x 21.3 cm; 1 31/32 in x 12 7/32 in x 8 3/8 in
place made
United States: Maryland, Baltimore
place patented
United States: Maryland, Baltimore
ID Number
accession number
catalog number
Science & Mathematics
See more items in
Medicine and Science: Mathematics
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of L. Leland Locke
Additional Media

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