Dr. George Merryweather’s 19th-century weather forecasting machine consisted of 12 glass jars, each containing a live leech that could ring a bell when a storm was approaching.
Some animals have an instinctive ability to predict changes in the weather. For example, when a storm is imminent, frogs croak, birds return to their nests, and cattle, sheep, and ants become restless.
A replica of the storm forecasting machine at the Whitby Museum, Whitby, England. (Photo: Badobadop/Wikimedia).
George Merryweather, a 19th-century English doctor and inventor, noticed that his medicinal leeches exhibited unusual behavior as the weather worsened. When placed in small glass jars filled with water, the leeches would relax at the bottom during good weather. However, a few hours before the skies turned gloomy and the winds began to blow, the leeches showed signs of agitation. If rain was imminent, they would crawl out of the water, and if a storm was approaching, they would curl up into a ball and remain in that state throughout the storm. Once the weather stabilized, the leeches would return to the bottom of the jar.
Merryweather decided to harness this ability of the leeches by creating a storm forecasting device described as an “Atmospheric Electromagnetic Telegraph, Controlled by Animal Instincts”, commonly referred to as the “Storm Forecasting Machine.”
The storm forecasting machine consisted of 12 glass jars, each containing a leech swimming in approximately 3.8 cm of water. The tops of the glass jars had a piece of whale bone positioned at the neck, connected by a wire to a small hammer used to strike a large metal bell. The 12 jars were arranged in a circular formation around the bell.
As a storm approached, changes in atmospheric pressure prompted the leeches to crawl out of the water towards the neck of the jar, displacing the whale bone and ringing the bell. Multiple bells ringing in succession indicated that the machine was forecasting an impending storm.
In a description of the device, Merryweather stated that the leeches were placed in the glass jars in a circular formation to prevent them from feeling distressed when confined alone. Around 1850, he spent over a year testing the device and wrote to the president of the Whitby Philosophical and Literary Society each time the “Leech Advisory Board” forecasted a storm. Merryweather later lobbied the government to use his design along the British coastline, but they opted for Robert FitzRoy’s glass tube storm forecasting system instead.
Merryweather’s storm forecasting machine did not gain the popularity he had hoped for. In fact, the original device displayed at the Great Exhibition in 1851 was even lost. A replica of this weather forecasting machine is currently on display at the Whitby Museum in England.
