Diff — Charles Babbage

Babbage's first great project was a machine to compute and print mathematical tables automatically, ending the era of error-ridden hand-calculated tables that cost lives at sea — navigational tables with mistakes were a documented cause of shipwrecks, and Babbage had personally found errors in official tables. Begun around 1822 with generous British government funding — ultimately some £17,000, roughly the cost of a warship — the Difference Engine ground gears to produce polynomial tables by the **method of finite differences**: if you know the first few values of a polynomial, every later value falls out of repeated addition, and addition is something brass wheels do well.

It was never finished. Disputes with his engineer Joseph Clement — who legally owned the specialized machine tools — spiraling costs, a move of the workshop that stalled progress for a year, and Babbage's own uncompromising temperament burned through the money and the government's patience. A completed Difference Engine No. 2, built from his plans by the Science Museum in London in **1991**, worked exactly as designed — vindication 120 years late.

Abandoning the single-purpose Difference Engine, Babbage designed something far greater: the [[Analytical Engine]], a *general-purpose* machine controlled by the [[Punched card|punched cards]] of the [[Jacquard Loom|Jacquard loom]]. With a memory store, an arithmetic "mill," conditional branching, and printed output, it was a computer in every modern sense — designed before the light bulb.

It was for this machine that [[Ada Lovelace]] wrote her famous notes in 1843, and it was Babbage's failure to build it that left her [[Bernoulli numbers|program]] — and his design — waiting nearly a century for hardware that could run them.

Babbage held the Lucasian Chair of Mathematics at Cambridge — Newton's chair — for eleven years (and never once lectured). He founded the Astronomical Society, helped found the Royal Statistical Society, worked on cryptography — he cracked the supposedly unbreakable **Vigenère cipher** in the 1850s and never published it — pioneered operational economics with *On the Economy of Machinery and Manufactures* (1832), and designed railway recorders, lighthouse signaling, and an ophthalmoscope.

He was brilliant, combative, and famously unable to suffer fools: he waged a documented war on London's street musicians, who responded by serenading his house — sometimes a hundred players at once. He died in 1871 with the Analytical Engine unbuilt; half his preserved brain rests at the Science Museum.

- "Babbage's complaint" — *"I wish to God these calculations had been executed by steam"* (1821) — is the founding gripe of all automation.

- [[Herman Hollerith]]