Object Name: fragment of Babbage's first difference engine
Date: 1822-1834, reassembled in 1886
Inventory Number: 1991-1-0001a
Dimensions: 36 x 40.5 x 43 cm (14 3/16 x 15 15/16 x 16 15/16 in.)
Description: Metal calculating wheels are here mounted on a rectangular wooden base with plastic label reading "Calculating Wheels / Designed By / Charles Babbage / 1834."
These posts, gears, and toothed wheels were assembled by Charles Babbage's son, Henry P. Babbage to illustrate the mechanism for addition used by his father in his first difference engine. The design shown is circa 1822 (not 1834 as labeled).
This sample is made up of fragments prepared by Babbage for his first difference engine, which was never completed in the 1820s because Babbage began work on the design of his second engine.
The German silver ring engraved with numerals was never attached to this piece. It was a sample of a ring showing a digit of a larger numeral.
In its present arrangement, the example will not operate. One half of the assembly is mounted 180 degrees off from the other. It should be turned in order to be correctly placed.
Inscribed: on plaque: Calculating Wheels / Designed By / Charles Babbage / 1834
Function: This mechanical device performed addition.
Historical Attributes: This portion of Charles Babbage's first difference engine is not a piece of the whole (which was never completed) but an assembly of parts from the 1822 design. Babbage went on to design a second engine even as he tinkered with the first design until 1834. The project was partially funded by the British government.
When the project was abandoned in 1842, the fragments were sold by the British government as waste metal. Babbage bought some for his own use. Upon his death in 1871, these parts were passed on to his son, Henry Prevost Babbage.
In 1886, Major-General Henry Prevost Babbage put some of the parts together to illustrate the process of addition. H. P. Babbage sent several such assemblies to a number of universities. Letters in the University Archive detail this gift to Harvard.
On March 13, 1997, this instrument was picked up from Howard H. Aiken Computation Lab along with other instruments. The instruments were transferred to CHSI by Edward P. Jackson, Facilitites Manager in the Division of Engineering and Applied Sciences. They originally were on exhibition in the entrance area adjacent to IBM Mark I computer on the first floor of the Aiken Lab.
Provenance: Charles Babbage; Henry P. Babbage; gift to Harvard in 1886.
Related Works: Science, 252 (1991): 1370-1371.
Scientific American, February 1993, pp. 8-91.
Michael Lindgren, Glory and Failure: The Difference Engines of Johann Muller, Charles Babbage, and Georg and Edvard Scheutz (Stockholm: Royal Institute of Technology Library, 1987).
Published References: I. Bernard Cohen, "Babbage and Aiken: With Notes on Henry Babbage's Gift to Harvard, and to Other Institutions, of a Portion of His Father's Difference Engine," Annals of the History of Computing, 10 (1988): 171-193.