For thousands of years, leeches have been used for medicinal purposes, but did you know that they were once used to predict the weather? In 1851, an English surgeon named George Merryweather created a device made of glass, silver, and brass that he called the “Tempest Prognosticator." Twelve glass bottles encircled the device, each one containing a leech and a few inches of rainwater. Merryweather observed that the leeches would become agitated whenever a storm was approaching. They would slide upwards towards the necks of the bottles, which in turn would trigger a wire connected to a central bell of the “Tempest Prognosticator.” The surgeon believed that the likelihood of a storm was predicted by the number of leeches that would ring this bell.
Dr. Merryweather tested the legitimacy of his claims for several months. He wrote letters to the Whitby Philosophical Society telling them of his discovery. While he believed leeches could be used to predict the weather, he admitted that they could not predict a storm’s direction or time of arrival.
Merryweather’s device earned him some positive reviews and fame, however fleeting. In 1851, he went on tour with the “Tempest Prognosticator,” and it was featured at the Great Exhibition in London's Hyde Park. The surgeon had grand ideas for his invention, including building a “Tempest Prognosticator” next to the largest bell in London’s St. Paul’s Cathedral. However, by 1854, the British government had deemed the idea impractical.
The strangest weather predictor:
- Although the original “Tempest Prognosticator” has been lost, three non-working replicas were made. Photographs and plans of these replicas were then used to recreate two working ones.
- Dr. Merryweather purposefully designed his “Tempest Prognosticator” to include glass bottles arranged in a circle so that the leeches wouldn’t feel the affliction of “solitary confinement.”
- Dr. Merryweather’s invention was inspired by a poem he read by Edward Jenner, creator of the smallpox vaccine.