Leeches Rang Bells Before Storms

In 1850, British physician George Merryweather developed the tempest prognosticator, a leech-powered barometer that used 12 leeches to warn of approaching storms. Each leech lived in its own bottle and, when disturbed by atmospheric conditions, tried to climb into a metal tube, dislodging a piece of whalebone that made a hammer strike a bell. The more often the bell rang, the more likely Merryweather considered a storm. He displayed an elaborate version at London's Great Exhibition in 1851, but the British government chose Robert FitzRoy's storm glass instead.

Previous Fact Next Fact