LONDON.- A rare Georgian clock, capable of recording changes in air pressure and used at the dawn of climate science, has been acquired for the nation by the Science Museum. The acquisition of this exceptional clock was made possible by a grant from Art Fund and was purchased through Sotheby's.

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.

Following 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'.

Inside the imposing 7ft 2in-high decorated case, thought to be made by famed London cabinet maker Thomas Chippendale, is a barograph mechanism used for measuring air pressure. The barograph 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.

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.

Ian Blatchford, Director of the Science Museum Group, said of the acquisition "Nothing beats the marriage of an exquisite object and an enquiring mind. We are delighted to have been able to save the barograph clock so that we can share the story of Luke Howard’s contribution to climate science with future generations."

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, and in fact the first barograph clock that Cumming constructed was commissioned by King George III as a prime example of his pursuit of Enlightenment.