Well dusted and with all brass fittings polished, it is displayed in the first gallery of the "Information Age" exhibit at the National Museum of American History. Though an amplified voice indicates the machine's importance in the history of science, it rarely draws a crowd. Never doubt, though, that the Difference Engine is a link to high-powered intellectual excitement, and to an astonishing man whom the British government has lately honored with his own postage stamp.
He is Charles Babbage, the man who more than years ago first faintly glimpsed today's computer age and strove to reach it. The Difference Engine is a calculator. It prepares numerical tables using a mathematical technique known as the method of difference.
Today such tables — the kind often used in navigation and astronomy — would be computed and stored electronically. Nearly a century and a half ago, the Difference Engine did much the same work, but slowly and mechanically. Each of its long shafts holds disks, and each disk has wheels with ten teeth that correspond to marks in the disks.
A scientist could set the disks with known figures, odd or even, turn a crank, and by reading down on each shaft, find the result of a calculation. This particular "engine" could also print out its answers. Sold to an observatory in Albany, New York, it was given to the Smithsonian in The Scheutzes had no interest in pleasing design. Their device worked well, though, for they had followed to practical completion the concepts of one of the 19th century's most brilliant minds.
Inventor and philosopher, Babbage produced a prototype of the original Difference Engine as early as , then kept adding refinements without ever quite finishing it. He enthusiastically endorsed the work of his friends Georg and Edvard Scheutz. But during the years it took them to complete their machine, the inventor's mind was groping toward a mechanical device that would go far beyond calculation.
It would actually store the data that it produced, then reuse the information to add more. Babbage described this process as "the engine eating its own tail. What he foresaw was a primitive computer. As his biographer, Anthony Hyman, wrote, "Babbage worked by himself, far ahead of contemporary thought. He had not only to elaborate the designs but to develop the concepts, the engineering, and even the tools to make the parts.
Charles Babbage was born in to a Devonshire family of wealth and leisure. He went to a good school, then set out for Cambridge with little inkling of what to expect there except for a warning that it was a bad place to buy wine. Babbage considered using number systems other than decimal including binary as well as number bases 3, 4, 5, 12, 16 and He settled for decimal out of engineering efficiency - to reduce the number of moving parts - as well as for their everyday familiarity.
Babbage began in with Difference Engine No. The design describes a machine to calculate a series of values and print results automatically in a table. Integral to the concept of the design is a printing apparatus mechanically coupled to the calculating section and integral to it. Difference Engine No. From time to time Babbage changed the capacity of the Engine. The design shows a machine calculating with sixteen digits and six orders of difference. The Engine called for some 25, parts shared equally between the calculating section and the printer.
Had it been built it would have weighed an estimated four tons and stood about eight feet high. Work was halted on the construction of the Engine in following a dispute with the engineer, Joseph Clement. Government funding was finally axed in With the construction project stalled, and freed from the nuts and bolts of detailed construction, Babbage conceived, in , a more ambitious machine, later called Analytical Engine, a general-purpose programmable computing engine.
The Analytical Engine has many essential features found in the modern digital computer. It was programmable using punched cards, an idea borrowed from the Jacquard loom used for weaving complex patterns in textiles. The Engine had a 'Store' where numbers and intermediate results could be held, and a separate 'Mill' where the arithmetic processing was performed. It had an internal repertoire of the four arithmetical functions and could perform direct multiplication and division.
By recombining these components, Henry produced the partial fragment held in the Whipple's collection Image 2 in , as a means of demonstrating the feasibility of his father's design. This fragment has only two axles, compared to the seven in the original, so it can only perform very simple calculations.
Indeed, it was used in the s in Cambridge University's computer laboratories to demonstrate the automation of simple addition. Booking is essential, but tickets are free. They are available at the University of Cambridge Museums website. Tickets are available for the subsequent week. Please note that, in line with University of Cambridge guidance, the Whipple Museum requires visitors to continue to wear face coverings unless exempt and maintain social distancing. Search site.
International students Continuing education Executive and professional education Courses in education. Research at Cambridge. Home Explore Calculating Devices. Sutton The 'Incomparable' Mr. Auzoux's Models Dr. Auzoux's Models overview Dr. Charles Babbage's Difference Engine.
Life and work. Difference Engine no. During a meeting with Herschel in to verify calculations made by human computers he lamented, "I wish to God these calculations had been executed by steam. Babbage often required support for the device from his friends in high scientific society, and John Herschel used a seafaring comparison to great rhetorical effect: "An undetected error in a logarithmic table is like a sunken rock at sea yet undiscovered, upon which it is impossible to say what wrecks may have taken place.
References Quoted in: D.
0コメント