Calculating Machines  Difference Engines
Difference Engines
Calculating machines were sometimes used to compute and print the mathematical tables widely used by nineteenth century engineers, mathematicians and scientists. A small number of digital computing machines computed and printed mathematical tables by finding successive values of a function using a mathematical technique known as the method of finite differences. The Englishman Charles Babbage proposed such a “difference engine” in 1820, and built a small section of it. Difference engines actually were built by Georg and Edvard Scheutz in Sweden and by George B. Grant in the United States. These pioneering devices were not widely adopted.

Model of Babbage's Difference Engine No. 1  Replica
 Description
 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.
 References:
 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.
 Location
 Currently not on view
 date made
 ca 1963
 date received
 1963
 maker
 Daniel I. Hadley & Associates
 ID Number
 MA.323584
 accession number
 252309
 catalog number
 323584
 Data Source
 National Museum of American History

Scheutz Difference Engine
 Description
 This is the first printing calculator sold. From ancient times, scientists and mathematicians have calculated numerical tables. These tables were often rife with error, both from incorrect calculations and from errors in reproduction. In the early 1800s, the English mathematician Charles Babbage proposed a machine called a difference engine that would compute and print automatically a large class of tables. Although Babbage's machine was never completed, it inspired the Swedish publisher Georg Scheutz and his son Edvard to build this instrument. It was exhibited at the world's fair held in Paris in 1855 and sold to the Dudley Observatory in Schenectedy, New York. It also was the first computing machine to carry out computations under U.S. government contract.
 For a related object, see 1988.0798.01.
 References:
 Merzbach, Uta C., Georg Scheutz and the First Printing Calculator, Washington, D.C.: Smithsonian Institution Press, 1977.
 Lindgren, Michael, Glory and Failure: The Difference Engines of Johann Mueller, Charles Babbage and Georg and Edvard Scheutz, trans. Craig G. McKay. Linkoping, Sweden: Linkoping University, 1987. Reprinted by MIT Press, 1990.
 Location
 Currently not on view
 date made
 1853
 maker
 Georg and Edvard Scheutz
 ID Number
 MA.323659
 catalog number
 323659
 accession number
 250163
 Data Source
 National Museum of American History

Sheet of Drawings of the Scheutz Difference Engine
 Description
 When the Scheutz difference engine was shipped to the Dudley Observatory in Albany, New York, in 1857, all the instructions provided for its use were this set of drawings and a letter explaining the procedure for converting the machine from operation in one number system to another.
 The frail tan paper sheet has a white cloth backing. On the sheet are 14 drawings labeled Fig. 1 through Figure 14. The figures are similar to but not identical with those in the final specifications for British Patent A.D. 1854, No. 2214, as reproduced in Merzbach. The numbering is somewhat different.
 For a related object, see the Scheutz difference engine, MA.323659.
 Reference:
 Merzbach, Uta C., Georg Scheutz and the First Printing Calculator, Washington, D.C.: Smithsonian Institution Press, 1977.
 Location
 Currently not on view
 date made
 ca 1857
 maker
 Georg and Edvard Scheutz
 ID Number
 1988.0798.01
 accession number
 1988.0798
 catalog number
 1988.0798.01
 Data Source
 National Museum of American History