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The barograph clock. Copyright the Board of theTrustees of the Science Museum, London.

A rare Georgian clock, capable of recording changes in air pressure and used at the dawn of climate science, has been acquired by the Science Museum in London. Dated 1766, the barograph clock is one of only four of its type that highly-regarded London clockmaker Alexander Cumming is known to have constructed. It was used by renowned meteorologist Luke Howard to conduct some of the world’s first urban climate studies.  After Cumming’s death in 1814, Luke Howard purchased the clock and used it for observations of atmospheric pressure at his homes in London and Ackworth, a crucial project in the emergence of climate science. The data from the barograph traces, accompanied by notes on global weather events and descriptions of the clock, were published in the book Barometrographia in 1847. Howard’s life’s work has earned him the nickname ‘the father of scientific meteorology’.

A fine example of the technical innovations of the Georgian period, the clock was designed by Cumming using ideas first outlined by Royal Society founding member Robert Hooke. It has featured in previous exhibitions at the Science Museum as a loan, and curators are now planning a permanent display.  The case, thought to be made by famed London cabinet maker Thomas Chippendale, contains a barograph mechanism used for measuring air pressure. This comprises two tubes of mercury in which a float rises and falls as atmospheric pressure changes. This data is recorded on the clock dial, which rotates once a year. The acquisition was made possible by a grant from Art Fund and it was purchased through Sotheby’s.

During the Georgian period, scientific practice was often presented in public as a high-status activity expressed through ornately decorated and very finely constructed instruments such as this. The first barograph clock Cumming constructed was commissioned by King George III as a prime example of his pursuit of Enlightenment.