Charles Babbage

Charles Babbage (December 26 1791 – October 18 1871) was an English mathematician, analytical philosopher and (proto-) computer scientist who originated the idea of a programmable computer. Parts of his uncompleted mechanisms are on display in the London Science Museum. In 1991, working from Babbage's original plans, a difference engine was completed, and functioned perfectly. It was built to tolerances achievable in the 19th century, indicating that Babbage's machine would have worked.

Design of computers

In recognition of the high error rate in the calculation of mathematical tables, Babbage sought to find a method by which they could be calculated mechanically, removing human sources of error. This idea may have come to him as early as 1812. Three different factors seem to have influenced him: a dislike of untidiness; his experience working on logarithmic tables; and existing work on calculating machines carried out by Wilhelm Schickard, Blaise Pascal, and Gottfried Leibniz. He first discussed the principles of a calculating engine in a letter to Sir Humphrey Davy in 1822.

Related Topics:
1812 - Logarithmic tables - Wilhelm Schickard - Blaise Pascal - Gottfried Leibniz - Humphrey Davy - 1822

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Difference engine

(See also Difference engine)

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Babbage presented a model of what he called a difference engine to the Royal Astronomical Society on June 14, 1822 and in a paper entitled "Note on the application of machinery to the computation of astronomical and mathematical tables."http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Babbage.html It calculated polynomials using a numerical method called the differences method. The Society approved the idea, prompting the government to grant £1500 for its construction in 1823.

Related Topics:
Difference engine - Royal Astronomical Society - June 14 - 1822 - Polynomial - Differences method - 1823

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Babbage converted one of the rooms in his home to a workshop and hired Joseph Clement to oversee construction of the engine. Every part had to be formed by hand using custom machine tools, many of which Babbage himself designed. He took extensive tours of industry to better understand manufacturing processes. Based on these trips and his experience with the difference engine, Babbage published On the Economy of Machinery and Manufacturehttp://www.gutenberg.org/etext/4238 in 1832. It was the first publication on what we would now call operations research.

Related Topics:
Joseph Clement - 1832 - Operations research

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The death of Georgiana, Babbage's father, and an infant son interrupted construction in 1827. Work had already taxed Babbage heavily and he was on the edge of a breakdown. John Herschel and several other friends convinced Babbage to take a trip to Europe to recuperate. He passed through the Netherlands, Belgium, Germany, and Italy visiting universities and manufacturing facilities.

Related Topics:
1827 - John Herschel - Netherlands - Belgium - Germany - Italy

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In Italy he learned he had been named the Lucasian Professor of Mathematics. He initially wanted to turn down the position but several friends convinced him to accept. He moved to 1 Dorset Street upon returning to England in 1828.

Related Topics:
Lucasian Professor of Mathematics - 1828

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The difference engine project had come under fire during Babbage's absence. Rumours had spread that Babbage had wasted the government's money; that the machine did not work; and that it had no practical value if it did. John Herschel and the Royal Society publicly defended the engine. The government continued its support, advancing £1500 on April 29, 1829, £3000 on December 3, and £3000 on February 24, 1830. Work continued, but Babbage would have continual difficulty getting money from the treasury.

Related Topics:
John Herschel - Royal Society - April 29 - 1829 - December 3 - February 24 - 1830

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Babbage's problems with the treasury coincided with numerous disagreements with Clement. Babbage had built a two-story, 50 foot long workshop behind his house. It had a glass roof for lighting, and a fireproof, dust-free room to contain the machine. Clement refused to move his operations to the new workshop and demanded more money for the difficulty of travelling across town to oversee construction. In response, Babbage suggested that Clement draw his pay directly from the treasury. Before then, Babbage would get money from the government that he would use to pay Clement. He often had to pay Clement out of his own pocket when the bureaucracy lagged behind Clement's pay schedule. Clement refused the request and stopped working.

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Clement further refused to turn over the drawings and tools used to build the difference engine. After an investment of £23000, including £6000 of Babbage's own money, work on the unfinished machine ceased in 1834. Charles wrote, "The drawings and parts of the Engine are at length in a place of safety—I am almost worn out with disgust and annoyance at the whole affair." In 1842 the government officially abandoned the project.

Related Topics:
1834 - 1842

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Analytical engine

(see also: Analytical engine)

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While he was separated from the difference engine, Babbage began to think about an improved calculating engine. Between 1833 and 1842 he tried to build a machine that would be programmable to do any kind of calculation, not just ones relating to polynomial equations. The first breakthrough came when he redirected the machine's output to the input for further equations. He described this as the machine "eating its own tail". It did not take much longer for him to define the main points of his analytical engine.

Related Topics:
1833 - 1842

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The mature analytical engine used punched cards adapted from the Jacquard loom to specify input and the calculations to perform. The engine consisted of two parts: the mill and the store. The mill, analogous to a modern computer's CPU, executed the operations on values retrieved from the store, which we would consider memory. It was the world's first general-purpose computer.

Related Topics:
Jacquard loom - CPU - Memory - Computer

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A design for this emerged by 1835. The scale of the work was truly incredible. Babbage and a handful of assistants created 500 large design drawings, 1000 sheets of mechanical notation, and 7000 sheets of scribbles. The completed mill would measure 15 feet tall and 6 feet in diameter. The 100 digit store would stretch to 25 feet long. Babbage constructed only small test parts for his new engine; a full engine was never completed. In 1842, following repeated failures to obtain funding from the First Lord of the Treasury, Babbage approached Sir Robert Peel for funding. Peel refused, and offered Babbage a knighthood instead. Babbage refused. He would continue modifying and improving the design for many years to come.

Related Topics:
1835 - 1842 - Robert Peel

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In October 1842, Federico Luigi, Conte Menabrea, an Italian general and mathematician, published a paper on the analytical engine. Augusta Ada King, Countess of Lovelace, a longtime friend of Babbage, translated the paper into English. Charles suggested that she add notes to accompany the paper. In a series of letters between 1842 and 1843, the pair collaborated on seven notes, the combined length of which was three times longer than the actual paper. In one note Ada prepared a table of execution for a program that Babbage wrote to calculate the Bernoulli numbers. In another, she wrote about a generalized algebra engine that could perform operations on symbols as well as numbers. Lovelace was perhaps the first to grasp the more general goals of Babbage?s machine, and some consider her the world's first computer programmer. She began work on a book describing the analytical engine in more detail, but it was never finished.

Related Topics:
1842 - Federico Luigi, Conte Menabrea - Augusta Ada King, Countess of Lovelace - 1843 - Bernoulli numbers

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Second difference engine

Between October 1846 and March 1849 Babbage started designing a second difference engine using knowledge gained from the analytical engine. It used only about 8000 parts, three times fewer than the first. It was a marvel of mechanical engineering.

Related Topics:
1846 - 1849

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Unlike the analytical engine that he continually tweaked and modified, he did not try to improve the second difference engine after completing the initial design. Babbage made no attempt to actually construct the machine.

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The 24 schematics remained in the Science Museum archives until a full-size replica was built 1985-1991 to celebrate the 200th anniversary of Babbage?s birth.http://www.sciencemuseum.org.uk/on-line/babbage/page4.asp. It measured 11 feet long, 7 feet high and 18 inches deep, and weighted 2.6 tonnes. The limits of precision were restricted to those achievable by Babbage.

Related Topics:
Science Museum - 1985 - 1991

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