Hart's Mercantile Computing Machine


The instrument consists of three concentric brass discs, a brass marker, a steel stop, and a wooden handle (instrument must be removed from box to find handle). Each brass disc has the numbers from 0 to 99 stamped around the edge. The two inner discs both have a circle of 100 holes just outside the numbers. The inner holes are used to add the last two digits of a number by rotation. Any hundreds value in the sum carries to the second set of holes, which are used to add hundreds and thousands places.

The machine is in a cylindrical wooden case with cover.

According to the Kirksville [Missouri] Democrat for August 2, 1888, by then Hart had sold 3500 of these devices and “he lately ordered one thousand more.”

References: U.S. Patent #199289

P. Kidwell, "Adders Made and Used in the United States," Rittenhouse, 1994, 8:78-96.

Kirksville [Missouri] Democrat, August 2, 1888.

Date Made: 1878

Patentee: Hart, WilliamMaker: Scovill Manufacturing Company

Location: Currently not on view

Place Made: United States: Connecticut, WaterburyPlace Patented: United States: Missouri, Kirksville

Subject: Mathematics


See more items in: Medicine and Science: Mathematics, Adder, Science & Mathematics


Exhibition Location:

Credit Line: Gift of Mrs. Robert T. Kerr

Data Source: National Museum of American History

Id Number: 1993.0510.01Accession Number: 1993.0510Catalog Number: 1993.0510.01

Object Name: adder with carry

Physical Description: steel (overall material)brass (overall material)wood (overall material)Measurements: overall: 5.5 cm x 13.5 cm x 13.5 cm; 2 5/32 in x 5 5/16 in x 5 5/16 in

Guid: http://n2t.net/ark:/65665/ng49ca746a5-0b41-704b-e053-15f76fa0b4fa

Record Id: nmah_690274

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