Alexander Calculating Machine


This is the U.S. Patent Office model for a lever-set non-printing adding machine. It has a wooden case with a curved metal front and back, and somewhat resembles an early cash register. It contains eight cogged wheels that rotate vertically on a common crosswise shaft. Each wheel is linked to a lever that extends from the front of the machine and is rotated upward to enter a number. The digits from 1 to 9 are stamped on the front of the case next to the opening for each lever, to indicate the digit being entered. Each large cogged wheel is linked to two smaller wheels. One turns forward, and gives the total entered. The second rotates in the opposite direction, and indicates differences. Each of the small wheels has the digits from 0 to 9 indicated around the edge.

The results recorded by these wheels are visible through two rows of windows at the top of the case. Each of these windows has a hinged cover. Every tenth tooth on a large wheel has a spring cog that drives the adjacent wheel, causing carrying and borrowing as needed. Multiplication is carried out by repeated addition. A row of keys at the front of the machine is used in division. There is a crank on the left side for zeroing the wheels associated with these keys. There is supposed to be a zeroing crank for the upper wheels, but none is on the model.

The machine is marked on the front at the base: IMPROVED CALCULATING MACHINE (/) INVENTED BY DR. J.B. ALEXANDER. It is marked on a paper tag attached to the left side: J.B. Alexander (/) Calculating (/) Machine (/) Received (/) 17th Decr (/) ‘63.

The physician Joseph Bell Alexander was born in North Carolina in about 1823. When he patented this adding machine, he was living in Baltimore. Alexander then moved to Washington, D.C., where he took out several other patents before his death in about 1872.


Joseph B. Alexander, “Improvement in Calculating Machines,” U.S. Patent 41898, March 15, 1864.

Date Made: 1864

Patentee: Alexander, Joseph B.Maker: Alexander, Joseph B.

Location: Currently not on view

Place Made: United States: Maryland, BaltimorePlace Patented: United States: Maryland, Baltimore

Subject: Mathematics

See more items in: Medicine and Science: Mathematics, Adding Machines, Science & Mathematics


Exhibition Location:

Data Source: National Museum of American History

Id Number: MA.309340Accession Number: 89797Catalog Number: 309340

Object Name: adding machineObject Type: Patent Model

Physical Description: copper (overall material)brass (overall material)paper (overall material)wood (overall material)Measurements: overall: 20 cm x 14 cm x 19 cm; 7 7/8 in x 5 1/2 in x 7 15/32 in


Record Id: nmah_690855

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