The Birthday of Geneviève de Prony (1755) – Human Computing

Gaspard de Prony (born 22 July 1755, sometimes old style) organised the largest pre‑electronic computation: 80 ‘computers’ using difference methods to produce 18‑digit trigonometric tables. He applied Adam Smith’s division of labour: mathematicians derived formulas, ‘technicians’ set up differences, and ‘computers’ (often hairdressers unemployed after the French Revolution) did repeated addition. The tables were never fully published (the project was too big), but the method inspired Babbage’s Difference Engine. De Prony showed that complex calculation can be decomposed into simple steps – a concept essential to modern programming.