Monday, July 28, 2014

Barometric bloodsuckers

On display at the Great Exhibition in the Crystal Palace in London in 1851 was a strange-looking device (REPLICA ABOVE). It was invented by English physician George Merrywether, who originally referred to it as "An Atmospheric Electromagnetic Telegraph, conducted by Animal Instinct." He had been inspired by the lines of a poem entitled Signs of Rain by fellow physician Edward Jenner:

The leech disturbed is newly risen

Quite to the summit of his prison.

Since leeches do in fact become agitated by an approaching storm, Merrywether harnessed 12 of them in separate bottles. When the barometric pressure changed they tried to climb out of the bottles, triggering small hammers to strike a bell. The more times the bell was struck, the greater the likelihood of a storm. The tempest prognosticator remains Merrywether's main legacy, even though the device failed to catch on.


Thanks, Sue!

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