Can You Predict the Weather with Leeches?

Thursday December 26, 2019 Written by James

Humans have tried to predict the weather for thousands of years, with varying degrees of success. Some, like English Mathematician, Lewis Fry Richardson, came up with complicated algorithms and forecasting formulas (Richardson’s modelling turned out to be handy for predicting war as well).

But 19th century English doctor George Merryweather tried leeches instead.

Merryweather (aptly named) noticed that leeches in his lab behaved oddly when the weather got worse. In sunny conditions, the leeches just relaxed at the bottom of their glass jars – as much as any leech can relax. But before a storm, each leech would climb out of their water and curl into a protective ball, clearly sensing the worst.

To harness the awesome, Nostradamus-like power of the leech, Merryweather in a machine called the Tempest Prognosticator. It consisted of twelve water-filled jars, each holding an individual leech. The jars were connected to bells via whalebone and bits of wire. When storms closed in, the leeches would climb to the top of their jars, disturbing the whalebone and ringing the bell.

That was the idea anyway. The invention never really caught on. Merryweather and his leeches lived out their days in relative obscurity. But you can still catch a replica of his Prognosticator at Whitby Town Museum.