Calculating engine, specimen piece, with instructions and engraving, 'Difference Engine No1', bronze / steel / wood / paper, designed by Charles Babbage, parts made by Joseph Clements, assembled by Henry Provost Babbage, England, 1822-1879
More than 150 years ago, the English mathematician, inventor, philosopher and reformer Charles Babbage designed a general-purpose mechanical calculating machine that anticipated the principles and structure of the modern computer.
In 1823 Babbage started working on his Difference Engine No1, a fully automatic machine that calculated and printed the tables used in the burgeoning fields of science, navigation and business. His aim was to relieve people of 'routine mental labour' and eliminate human error in calculations with a perfect machine.
The Difference Engine was designed to produce successive values of a polynomial function using the Method of Finite Differences. This method reduced the calculation to a series of additions. Once the initial values were entered into the machine the operator need only to turn the handle to generate the tables. Most significantly, the operator didn't need to know any mathematics.
Babbage worked on the Difference Engine No1 for 11 years but was never able to complete it. There are a number of factors that contributed to his failure including the strain and expense of having to develop new manufacturing machining techniques, personality clashes especially with his engineer, the death of his wife and several of his children and the general lack of understanding of his project.
He was perhaps also distracted by his conception for a more ambitious machine, the Analytical Engine, a machine capable of finding values for any algebraic function. Like the modern computer, it was to be a general purpose, programmable machine in which the storage of information was a separate function to the processing of information. The Analytical Engine was never built and the ideas he developed had to wait another 100 years to be "rediscovered".
While Babbage did not successfully complete any of his engines, his efforts had profound impact in other ways, particularly in the "mechanical arts" and on the organisation of manufacturing processes.
In 1879 Charles Babbage's son Henry assembled this portion of the Difference Engine from original parts after his father's death. It was one of six specimens constructed to demonstrate the addition and carry mechanism. The Powerhouse Museum acquired it in 1996 and it is on display in Cyberworlds: computers and connections.
The Difference Engine No1 was designed by Charles Babbage between 1822 and 1833 after which the project was abandoned. The mechanism demonstrated in the specimen was probably designed in the early stages. He designed the engine to automatically calculate and print mathematical tables, used at the time for complex calculations relating to navigation, surveying, astronomy, annuities etc.
The engine used the Method of Finite Differences to generate successive values of a polynomial function.
In order to construct the parts new tools and manufacturing techniques had also to be developed. Most of the parts were eventually made but the machine was never assembled.
While he was working on the Difference Engine he started to think about a machine that could be more versatile. When the Difference engine project was abandoned he went on to design most of the Analytical Engine which was in effect a programmable mechanical computer with the same architecture as a modern electronic computer. Certain innovations he developed for the Analytical Engine were late incorporated into a more efficient difference engine, Difference Engine No2.
The parts for the Difference Engine were made by Joseph Clement who was a highly skilled toolmaker and tradesman.
The unassembled parts of the Difference Engine were inherited by Henry Provost Babbage after the death of his father in 1871. In 1879 he assembled 5, 6 or 7 specimen pieces (accounts in the writings of Henry differ). These pieces were to demonstrate the addition and carry mechanism of the engine. One he gave to the Whipple Musuem, Cambridge; one to University College, London (now at the Science Museum); one to Harvard College in America; and one to Charles Whitmore Babbage, Henry's nephew who took it to New Zealand. Others are unaccounted for.
None of Babbages machines was ever completed. But in 1832 he assembled a working portion to demonstate its function to the British Parliment in what was was probably a last attempt to gain continued funding. This portion now at the Science museum was capable of generating, but not printing tables for 2nd degree polynomials. Babbage did generate tables for some functions.
The descendants offered the Engine and related material for auction through Christie's of London on 4 October 1995.