Alexander E. Braun

Ruminations on What Might Have Been
June 12, 2008

Over the weekend I went to the Computer History Museum, here in Silicon Valley. They currently have on exhibit one of the two existing Difference Engines No. 2, designed by Charles Babbage. I stood in silent stunned admiration before the glorious array of 8,000 dazzling bright gears, cams, and assorted parts harmoniously working together in a formidable five-ton frame, 11 feet long and seven feet high. When one of the docents turned the crank and operated it, its various components—made of brass, iron, and steel—seemed to spin in three-quarter time, closely engaged in an elegant mathematical waltz. (Video)



Difference Engine No. 2

It felt as if I were looking at something out of a Victorian science-fiction story. Had I been brought face to face with Captain Nemo’s Nautilus, or Wells’ time machine, the feeling would have been no different. The soft whirring of the gears induced me to think of possible multiverses.

Charles Babbage (1791-1871) was an inventor and mathematician. In 1821, while going over log tables that had been calculated by hand (in those days, “computer” referred to a person who did that sort of mathematical calculation for a living), he became frustrated over the fact that these tables, used for astronomy, navigation, engineering, etc., were plagued with errors. His famous exclamation, “I wish to God these calculations had been executed by steam!” (meaning done infallibly, by machine), charted the course of the rest of his life, along a path of frustration.



Charles Babbage

Babbage invented what he called a “Difference Engine,” a calculating machine to generate flawless scientific tables. It was not designed for basic arithmetic, but to calculate a series of numerical values and print the results. It used what was termed the “method of finite differences,” which eliminated the need for multiplication and division in calculating polynomials. The Engine uses only addition—simpler to mechanize than multiplication and division. Babbage convinced The Royal Society of its worth and was awarded £1,500 to fund it. Although the prototype was supposed to have been ready in three years, Babbage ran into many of the problems that people ahead of their time often do. He began work during an era that was starting on the transition from artisan’s workshop to machine shop, and almost every component required special hand-made jigs and tools to be produced. Also, as the work proceeded, he’d come up with modifications and enhancements for his machine, which often required retooling.

After investing enough funds on Babbage’s device to have built a battleship, the British government withdrew its support. Undaunted, in 1834, Babbage began the design of his far more ambitious Analytical Engine, which he described as “a machine of the most general nature.” Unlike calculating devices built during the period, the Analytical Engine was not designed for a specific application; its design included practically all the essential logical features of a modern digital computer. It was programmable using punched cards. It had a “store” (memory) where 100 40-digit numbers and intermediate results could be held, and a separate “mill” (CPU) where the arithmetic processing was performed. The Analytical Engine could be “looped” (repeat the same operation sequences a predetermined number of times), and was capable of conditional branching (IF— THEN— statements); that is, it could automatically take alternative courses of action depending on a calculation’s result.

Ada Byron, Countess of Lovelace, a friend of Babbage’s, was one of the few to understand the Analytical Engine’s potential, comparing it to the period’s state-of-the-art Jacquard loom: “The Analytical Engine weaves algebraic patterns just as the Jacquard loom weaves flowers and leaves,” she said. In fact, she wrote a description of the machine and worked on manipulating symbols according to rules—to operate the machine—making her the first programmer.

It is fitting that the Analytical Engine was to have been steam-driven, as it would have been incredibly complex and about the size of a locomotive. It is interesting to speculate what direction our timeline would have taken, had it been built. As with the Difference Engine, there is little doubt that the Analytical Engine would have performed as designed. What would the world look like had the principles of true computing been proven practically a century ago and developed further over that time? The thought boggles the mind. Imagine a series of these devices across the British Empire and the rest of the world, connected via telegraph, forming a primitive network, working in unison to solve intractable problems and keep track of things.

Until 2002, 150 years later, when the first complete, full-size Differential Engine No. 2 was built by the Science Museum in London, all that existed of the concept were Babbage’s drawings and small, working sections of what would have been the whole. It has often been stated that these machines weren’t built because the technology of the time was not up to providing the tolerances required for the components. This was disproven by the Science Museum when it successfully undertook to build Babbage’s first brainchild using only the techniques and technology of the inventor’s period.

Considering the many technologies that date back to that time—electricity and the electric light, refrigeration, sound recording—it’s obvious that the Analytical Engine could have been built. If there only had been a National Cash Register (NCR) or International Business Machines (IBM) complex of corporations then that might have taken on the development work as it often happens today, Charles Babbage and his Analytical Engine would be on a par with Edison and Shockley, instead of just being a curious footnote in the history of technology.

When the demonstration ended and the gears stopped, the spell broke. I left, shaking my head and muttering, “What if?”

Posted by Alexander E. Braun on June 12, 2008 | Comments (8)