Model of Babbage's Difference Engine No. 1 - Replica

This is a replica of the portion of a difference engine built by Charles Babbage in 1832. Babbage, an English mathematician, hoped to compute and to print astronomical tables by machine. He proposed to estimate the value of functions using polynomials, and to use the method of finite distances to compute results.
Babbage never completed either a difference engine or a more complex, programmable instrument he dubbed an analytical engine.
The machine has three columns of discs. The leftmost column has six discs, each with the numbers from 0 to 9. The middle column has seven discs. The six lower ones each have the digits from 0 to 9. The uppermost disc is marked as indicated. The rightmost column has five discs numbered from 0 to 9. Above these are four discs, similarly numbered, that are immediately adjacent to one another. On the top of the machine are a gear train and a handle. The machine has a metal framework and a wooden base. The replica has containers for springs, but no springs.
The overall dimensions include the handle. Without it, the dimensions are: 59 cm. w. x 43.5 cm. d. x 72 cm. h.
The replica was built for display in the first exhibition devoted to mathematics and computing at the Museum of History and Technology (now the National Museum of American History). A similar replica is in the collections of IBM Corporation.
The original on which this replica is based is at the Science Museum in London. That museum also displays a more recent attempt to build a working version of Babbage’s difference engine.
Merzbach, Uta C., Georg Scheutz and the First Printing Calculator, Washington, D.C.: Smithsonian Institution Press, 1977.
Swade, Doron. The Difference Engine: Charles Babbage and the Quest to Build the First Computer, New York: Viking, 2000.
Object Name
difference engine
date made
ca 1963
date received
Daniel I. Hadley & Associates
Physical Description
metal (overall material)
wood (overall material)
overall: 72 cm x 74 cm x 49 cm; 28 11/32 in x 29 1/8 in x 19 9/32 in
ID Number
accession number
catalog number
Computers & Business Machines
Calculating Machines
See more items in
Medicine and Science: Mathematics
Calculating Machines
Fantastic Worlds
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of International Business Machines Corporation
Additional Media

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