Adders - Circular Adders
On some adders, numbers were represented along an arc of a circle. People used their fingers or a stylus to enter numbers. On a few of these instruments, a mechanism allowed one to carry a single digit. These objects are described here as adders with carry. They blur the line between adders and adding machines.
"Adders - Circular Adders" showing 12 items.
Page 2 of 2
C.W. Hergenroeder Adding Machine
- Description
- 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.
- Location
- Currently not on view
- date made
- 1882
- patentee
- Hergenroeder, Christian W.
- maker
- Hergenroeder, Christian W.
- ID Number
- MA*311960
- accession number
- 155183
- catalog number
- 311960
- Data Source
- National Museum of American History, Kenneth E. Behring Center
Prewett Addograf
- Description
- This aluminum device consists of two discs sealed together at the rim, with a rotating disc in between. Various numbers are stamped around the rim of the rotating disc. Openings in the outer discs reveal three numbers on either side at one time. One side of the instrument has the numbers from 1 to 20 stamped clockwise around the scalloped rim of the movable disc. The other side of this disc has the numbers from 21 to 40, also stamped clockwise.
- At the top of the instrument, three alternate numbers are visible (i.e., 1, 3, 5). Three alternate numbers also are visible on the reverse side (i.e., 35, 37, 39). The sum of two numbers on opposite sides of the disc is always 40 (i.e., 1 and 39). Part of the scalloped edge of the movable disc is exposed at the bottom.
- Clay W. Prewett and the Prewett Addograf and System Company (also known as the Prewett System Company) of Los Angeles, California, sold this device. A 1940 brochure describing “The Prewett Addograf and System” indicated that it consisted of not only this instrument but a $10 brochure describing how it worked, a $5 brochure on modern short cuts in multiplication, division, interest, fractions, and mixed numbers; and a $5 multiplication chart. The entire system could be purchased for $15. It was not returnable.
- Location
- Currently not on view
- date made
- 1940
- maker
- Prewett System Company
- ID Number
- MA*155183.28
- catalog number
- 155183.28
- accession number
- 155183
- Data Source
- National Museum of American History, Kenneth E. Behring Center