History
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The decisions, accidents and people that shaped now.
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How one doctor's map traced a cholera outbreak to a single pump
In 1854 most doctors blamed cholera on bad air. When it tore through Soho, killing hundreds in days, John Snow went door to door asking one question: where did…
How a 9th-century scholar cracked secret codes by counting letters
For roughly nine centuries after Julius Caesar, swapping each letter for another was a perfectly good way to keep a secret. Then, in 9th-century Baghdad, the…