121. George Merryweather’s Tempest Prognosticator

21 May

The 19th Century was the true birth of weather in Europe. People now were acknowledging the importance of knowing what might happen with the weather, so devices were designed. One of the most effective and bizarre was the grandly named ‘Tempest Prognosticator’ designed and tested by George Merryweather during 1850.

It was a grand construction, consisting of twelve pint bottles arranged in a circle around the centrepiece, like some bizarre Merry-Go-Round. Out of their tops came a small chain, which fed up through a pulley and each continued towards its own respective, miniature hammer. Between all the hammers was a bell. This bizarre contraption was powered by a not common source of weather knowledge, the Leech.

Into each of the twelve vessels was poured one and a half inches of rainwater, and a single leech. The pint bottles were made of clear glass so as to spare the leeches “the affliction of solitary confinement”. George Merryweather realised that during the conditions which preceded a storm all leeches would climb to a higher spot, away from water. So this effect was utilised fully. The necks of the bottles were obscured by a piece of whalebone connected to the bottom end of a chain. George Merryweather then described the workings as such:

“When influenced by the electromagnetic state of the atmosphere a number of leeches ascended into the tubes; in doing which they dislodged the whalebone and caused the bell to ring.”

How the Tempest Prognosticator works

So a single leech forcing its way out would cause the bell to be struck once. The more times the bell was struck,  the greater the chance of a storm. Merryweather described the Leeches as being his “jury of philosophical councilors” –  surely one of the grander titles bestowed upon the simple organism, although it may have been warranted.

Although it may sound impractical it was proven to function. He constructed one full Tempest Prognosticator himself and whenever the bells tolled he wrote of the impending storm and sent news to his colleagues. 28 of his predictions are kept in the library of the Whitby Museum. I his essay Mr Merryweather touted the high success rate of his Tempest Prognosticator. That was not enough though; he envisioned a full network though, not just his solitary unit. He produced six designs ranging in cost, size and number of leeches. It was his hope to establish a wide Leech network encompassing the totality of Great Britain and all her Isles.

Unfortunately it was not to be. He campaigned for the devices, including giving a three-hour essay to the Philosophical Society lengthily entitled “Essay explanatory of the Tempest Prognosticator in the building of the Great Exhibition for the Works of Industry of All Nations.” He was a great proponent of the further proliferation of his constructions but to no avail, a cheaper and Leech-free alternative was found and distributed.

The Tempest Prognosticator was a brilliant if contrived construction. A brilliant and bizarre piece – one of kind. The original was the only one ever to be constructed. Two replicas have since been constructed for its 100th anniversary in 1951. Once described by Merryweather himself as a “mousetrap contrivance” the only working replica today stands, gathering dust in the halls of Barometer World, near Okehampton, England. An odd footnote in the annals of Meteorology.


Posted by on May 21, 2011 in Articles, Trivia


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2 responses to “121. George Merryweather’s Tempest Prognosticator

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