ON THIS DAY in 1838, Sir Mortimer Throttle first demonstrated his Arithmetical Engine, a mechanical computer so complex that it had taken Sir Mortimer and the village blacksmith more than thirty years to construct. The machine was made mostly of iron, which did not admit of very precise mechanics; it was therefore very large, and occupied a great barn behind the main house at Throttleworth, Sir Mortimer’s ancestral home. The local villagers had long since come to the conclusion that Sir Mortimer was mad—an opinion which he did nothing to discourage, since it tended to keep stray villagers out of his way. Nevertheless, a fair number of them showed up to view the demonstration, which was also attended by most of the Royal Society and a certain number of curiosity-seekers from London.

A local brass band played “When Last the Sukebind Bloom’d Aloft,” and everything was done to make the affair a gay occasion. Everyone waited with gleeful anticipation to see the machine perform its first addition. Sir Mortimer, meanwhile, was poring over the details of what he called his “operating system,” a booklet of instructions for the correct manipulation of the many thousands of parts in the machine. At the appointed moment, Sir Mortimer, with the assistance of the blacksmith, adjusted the switches, lubricated the pinions, and carefully placed the muppocks over the joints; then he set the first of the machine’s enormous dials to the number 2, and the second to the number 2 as well. When everything was set to his satisfaction, and he had placed a small tick mark beside each step in his operating system, Sir Mortimer and the blacksmith, working together and using all their strength, turned the great crank that set the machinery in motion. The hand of the third dial began to move, and it continued to move slowly until it came to rest at the number 5.

This was not quite the result they had hoped for; but every subsequent trial produced the same result. No matter how much oil Sir Mortimer used in the lubrication, or how forcefully he and the blacksmith turned the crank, the Arithmetical Engine remained convinced that 2 + 2 = 5.

After this public humiliation, Sir Mortimer gave up the project in disgust and devoted the rest of his life to breeding irises. Eventually the resourceful blacksmith turned the Arithmetical Engine into a combine harvester, the first machine of its kind and the foundation of a gigantic industry from which he profited enormously.

Nevertheless, although the Arithmetical Engine was itself a failure, the operating system invented by Sir Mortimer Throttle was passed down from one mathematician to another, adapted in digital form, and eventually formed the basis of the Unix operating system still in use on some computers today. Curiously enough, the computation “2 + 2” still yields the answer “5” even in up-to-date Unix systems; but in the current academic climate this is no longer considered a liability.