History

15 breaks

The decisions, accidents and people that shaped now.

AllBiologyComputingEarth & SpaceEconomicsEngineeringFood ScienceHistoryLanguageMathsMindMusic & SoundPhysics
How a bone tells its own age: carbon-14 and the clock that starts at death Every living thing carries a trace of carbon-14, about one atom in a trillion, topped up with every meal. At death the topping-up stops and the clock starts… History4 min read Why Egyptians poured water on sand: the wet-sand trick for dragging giant stones A wall painting in an Egyptian tomb shows 172 men hauling a colossal statue on a sledge, while one man pours water onto the sand in front of it. In 2014… History4 min read How two royal names in rings cracked hieroglyphs: Ptolemy, Cleopatra and the Rosetta Stone In 1799 a slab was dug up near Rosetta carrying one decree in three scripts, and nobody could read two of them. The first foothold was tiny: royal names sealed… History4 min read How a stick's shadow measured the whole Earth: Eratosthenes, a well and 5,000 stadia Two sticks, one shadow and one distance were enough for Eratosthenes to size the whole planet around 240 BC. On the summer solstice the noon Sun shone straight… History4 min read How a clock found longitude at sea: Harrison's H4 and the £20,000 prize In 1707 a British fleet hit the rocks off Scilly because navigators could not find longitude. Seven years later Parliament offered £20,000 for a method… History4 min read How a map of dots found a cholera pump in 1854: John Snow and Broad Street In late August 1854, cholera tore through a few streets of Soho, killing roughly 600 people in weeks. Almost everyone blamed foul air. John Snow suspected the… History4 min read How a beam with no date gets one: tree rings and crossdating A beam from a ruined house has no date on it, but its rings do. Trees from the same region share the same wide and thin years, so a pattern of ring widths can… History5 min read How a stick and a well measured the whole Earth: Eratosthenes Around 240 BC, the librarian Eratosthenes measured the size of the Earth using a well, a stick and a shadow. At noon on the summer solstice the sun shone… History4 min read Why washing hands saved mothers in 1847: Semmelweis and the two wards In 1846, mothers in one Vienna maternity ward died at four times the rate of mothers in the ward next door. The doctors' ward was losing 11.4% of its patients… History3 min read How a 2,000-year-old bronze machine predicted eclipses with the number 223 In 1901, divers pulled a corroded bronze machine from a shipwreck off the Greek island of Antikythera. One dial ended in the number 223, written in Greek… History4 min read 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… History5 min read 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… History5 min read