Tempest Prognosticator
Encyclopedia
The Tempest Prognosticator, also known as the Leech Barometer, is a 19th century invention by George Merryweather
in which leech
es are used in a barometer
. The twelve leeches are kept in small bottles inside the device; when they become agitated by an approaching storm
they attempt to climb out of the bottles and trigger a small hammer which strikes a bell. The likelihood of a storm is indicated by the number of times the bell is struck.
of the Whitby Literary and Philosophical Society's Museum, detailed the sensitivity that medicinal leeches displayed in reaction to electrical conditions in the atmosphere. He was inspired by two lines from Edward Jenner
's poem Signs of Rain: "The leech disturbed is newly risen; Quite to the summit of his prison." Merryweather spent much of 1850 developing his ideas and came up with six designs for what he originally referred to as "An Atmospheric Electromagnetic Telegraph, conducted by Animal Instinct." These ranged from a cheap version that he envisaged would be used by the government and the shipping industries to a more expensive design. The expensive design, which took inspiration from the architecture of Indian temples, was made by local craftsmen and shown in the 1851 Great Exhibition
at The Crystal Palace
in London
.
On 27 February 1851 he gave a near three-hour essay to members of the Philosophical Society entitled "Essay explanatory of the Tempest Prognosticator in the building of the Great Exhibition for the Works of Industry of All Nations."
The leech would have difficulty entering the metal tubes but would endeavour to do so if sufficiently motivated by the likelihood of bad weather. By ringing the bell it would signify that that individual leech is indicating that a storm is approaching. Merryweather referred to the leeches as his "jury of philosophical councilors" and that the more of them that rang the bell the more likely that a storm would occur.
In his essay Merryweather also noted other features of the design, including the fact that the leeches were placed in glass bottles placed in a circle to prevent them from feeling "the affliction of solitary confinement".
. Merryweather stated in his essay the great success that he had had with the device.
Merryweather lobbied for the government to make use of his design around the British coastline but they instead opted for Robert FitzRoy
's storm glass
.
. This working version was made from the description in a printed copy of Merryweather's essay and a copperplate drawing of the original. The device was shown in the Dome of Discovery
and given to the Whitby Philosophical Society when the festival ended. Plans and photographs of this replica were then used to create a faithful working model now found at Barometer World
near Okehampton
, Devon
.
George Merryweather
Dr. George Merryweather M.D. was born on 10 April 1794 in Burley in Wharfedale, Yorkshire, England. He married Jane Anderson Loy in 1826. They had four children: Mary, Jane, John and Emily. He then married Hannah Baker in 1844, after the death of his first wife in 1832. Merryweather died on 4...
in which leech
Leech
Leeches are segmented worms that belong to the phylum Annelida and comprise the subclass Hirudinea. Like other oligochaetes such as earthworms, leeches share a clitellum and are hermaphrodites. Nevertheless, they differ from other oligochaetes in significant ways...
es are used in a barometer
Barometer
A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. Pressure tendency can forecast short term changes in the weather...
. The twelve leeches are kept in small bottles inside the device; when they become agitated by an approaching storm
Storm
A storm is any disturbed state of an astronomical body's atmosphere, especially affecting its surface, and strongly implying severe weather...
they attempt to climb out of the bottles and trigger a small hammer which strikes a bell. The likelihood of a storm is indicated by the number of times the bell is struck.
Invention and development
Dr. Merryweather, honorary curatorCurator
A curator is a manager or overseer. Traditionally, a curator or keeper of a cultural heritage institution is a content specialist responsible for an institution's collections and involved with the interpretation of heritage material...
of the Whitby Literary and Philosophical Society's Museum, detailed the sensitivity that medicinal leeches displayed in reaction to electrical conditions in the atmosphere. He was inspired by two lines from Edward Jenner
Edward Jenner
Edward Anthony Jenner was an English scientist who studied his natural surroundings in Berkeley, Gloucestershire...
's poem Signs of Rain: "The leech disturbed is newly risen; Quite to the summit of his prison." Merryweather spent much of 1850 developing his ideas and came up with six designs for what he originally referred to as "An Atmospheric Electromagnetic Telegraph, conducted by Animal Instinct." These ranged from a cheap version that he envisaged would be used by the government and the shipping industries to a more expensive design. The expensive design, which took inspiration from the architecture of Indian temples, was made by local craftsmen and shown in the 1851 Great Exhibition
The Great Exhibition
The Great Exhibition of the Works of Industry of all Nations or The Great Exhibition, sometimes referred to as the Crystal Palace Exhibition in reference to the temporary structure in which it was held, was an international exhibition that took place in Hyde Park, London, from 1 May to 15 October...
at The Crystal Palace
The Crystal Palace
The Crystal Palace was a cast-iron and glass building originally erected in Hyde Park, London, England, to house the Great Exhibition of 1851. More than 14,000 exhibitors from around the world gathered in the Palace's of exhibition space to display examples of the latest technology developed in...
in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
.
On 27 February 1851 he gave a near three-hour essay to members of the Philosophical Society entitled "Essay explanatory of the Tempest Prognosticator in the building of the Great Exhibition for the Works of Industry of All Nations."
Method
The Tempest Prognosticator comprises twelve pint bottles in a circle around and beneath a large bell. Atop the glasses are small metal tubes which contain a piece of whalebone and a wire connecting them to small hammers positioned to strike the bell. In his essay Merryweather described the workings of the device:The leech would have difficulty entering the metal tubes but would endeavour to do so if sufficiently motivated by the likelihood of bad weather. By ringing the bell it would signify that that individual leech is indicating that a storm is approaching. Merryweather referred to the leeches as his "jury of philosophical councilors" and that the more of them that rang the bell the more likely that a storm would occur.
In his essay Merryweather also noted other features of the design, including the fact that the leeches were placed in glass bottles placed in a circle to prevent them from feeling "the affliction of solitary confinement".
Accuracy and success
Merryweather spent all of 1850 testing the device, sending a letter to the president of the Philosophical Society and the Whitby Institute, Henry Belcher, to warn him of an impending storm. The results of 28 of these predictions are kept in the library of Whitby MuseumWhitby Museum
Whitby Museum is a private museum in Whitby, North Yorkshire, England, run by Whitby Literary and Philosophical Society, a learned society and registered charity, established in 1823....
. Merryweather stated in his essay the great success that he had had with the device.
Merryweather lobbied for the government to make use of his design around the British coastline but they instead opted for Robert FitzRoy
Robert FitzRoy
Vice-Admiral Robert FitzRoy RN achieved lasting fame as the captain of HMS Beagle during Charles Darwin's famous voyage, and as a pioneering meteorologist who made accurate weather forecasting a reality...
's storm glass
Storm glass
A storm glass is a type of weather forecasting device, composed of a sealed glass container, filled with liquid, that allows the user to forecast the weather by observing the appearance of the liquid in the glass.-Description:...
.
Replicas
The original device has been lost, but at least two replicas have been made. The hundredth anniversary of the invention brought renewed interest as a replica was made for the 1951 Festival of BritainFestival of Britain
The Festival of Britain was a national exhibition in Britain in the summer of 1951. It was organised by the government to give Britons a feeling of recovery in the aftermath of war and to promote good quality design in the rebuilding of British towns and cities. The Festival's centrepiece was in...
. This working version was made from the description in a printed copy of Merryweather's essay and a copperplate drawing of the original. The device was shown in the Dome of Discovery
Dome of Discovery
The Dome of Discovery was a temporary exhibition building designed by architect Ralph Tubbs for the Festival of Britain celebrations which took place on London's South Bank in 1951. The consulting engineers were Freeman Fox and Partners, in particular Oleg Kerensky The Dome of Discovery was a...
and given to the Whitby Philosophical Society when the festival ended. Plans and photographs of this replica were then used to create a faithful working model now found at Barometer World
Barometer World
Barometer World was established in 1979 by Philip Collins, is located in the village of Merton, near Great Torrington, Devon, UK and is the world's largest barometer museum . Barometer World makes, sells and restores barometers of a variety of types.-History:...
near Okehampton
Okehampton
Okehampton is a town and civil parish in West Devon in the English county of Devon. It is situated at the northern edge of Dartmoor, and has an estimated population of 7,155.-History:...
, Devon
Devon
Devon is a large county in southwestern England. The county is sometimes referred to as Devonshire, although the term is rarely used inside the county itself as the county has never been officially "shired", it often indicates a traditional or historical context.The county shares borders with...
.