Barometer store in England features reproduction of a "Tempest Prognosticator," a.k.a "Leech Barometer"

Joshua Foer is a guest blogger on Boing Boing. Joshua is a freelance science journalist and the co-founder of the Atlas Obscura: A Compendium of the World's Wonders, Curiosities, and Esoterica, with Dylan Thuras.


Barometer World is a store in Okephampton, England that specializes in the sale and repair of instruments that determine atmospheric pressure. After two years of research, its proprietor built a reproduction of one of the most whimsical weather-forecasting devices of all time, the "Tempest Prognosticator," a.k.a. the "Leech Barometer," a.k.a. the "Atmospheric Electromagnetic
Telegraph." The instrument, which uses fresh water leeches to predict incoming storms, was first exhibited at the Great Exhibition in London in

A contemporary account of the invention described it as an
"elaborate and highly ornate apparatus… evolved by a certain Dr.
Merryweather (no epigram intended) who had observed that during the
period before the onset of a severe storm, fresh water leaches tended
to become particularly agitated. The learned Doctor decided to harness
the physical energy of these surprisingly hysterical aquatic
bloodsuckers to operate an early warning system. On the circular base
of his apparatus he installed glass jars, in each of which a leech was
imprisoned and attached to a fine chain that led up to a miniature
belfry–from whence the tinkling tocsin would be sounded on the
approach of a tempest."

The more bells that rang, the greater the likelihood of an impending storm.

UPDATE: The above photograph is of the other Tempest Prognosticator reproduction, built in 1951 for the Whitby Museum in North Yorkshire.

Barometer World & Museum [Atlas Obscura]

Barometer World web site