Measuring an isotope of carbon to find out how old an organic object is. See 'Some Notes on Archaeology'.
Radiocarbon dating
Fact of the Day
Philip II of France decided on his wedding day that he didn't like his wife. So he sent her to a nunnery and ordered her to stay there.
Quote of the Day
"Total abstinence is so excellent a thing that it cannot be carried to too great an extent. In my passion for it I even carry it so far as to totally abstain from total abstinence itself.
"
~ Mark Twain
On This Day
1284 The future Edward II was born at Caernarfon Castle, Wales. He was the only son from Edward I's first marriage to Eleanor of Castile to outlive his father.
1719 The much-loved Daniel Defoe story Robinson Crusoe was published.
1792 French highwayman Nicolas Jacques Pelletier became the first person to be executed by the guillotine.
1915 Ninety thousand Australian, New Zealand, British and French forces began landing on the Turkish Gallipoli Peninsula. They hoped to secure the northern bank of the Dardanelles, but were forced to withdraw after eight months of intense fighting.
1916 British authorities declared martial law in Dublin for a month, in response to the Easter Rising.
1984 David A. Kennedy, son of Robert F. Kennedy (of the political Kennedy family), died of a drug overdose in Palm Beach, aged 28.
1990 The US shuttle Discovery released the Hubble Telescope into orbit. It remains one of the largest, most versatile and best known space telescopes.