One of the world’s rarest ‘sign post’ angle barometers – spotted among items in a car boot – has stunned experts at a Derbyshire auction house.
Karl Martin, a valuer at Hansons Auctioneers at Etwall, near Derby, was amazed when he saw the valuable object, used to measure atmospheric pressure to forecast the weather, among objects brought along for free valuation.
The George III mahogany barometer, dated 1766, was made by renowned scientist John Whitehurst of Derby, a leading instrument and clock maker. It’s now set to go under the hammer in Hansons’ Derbyshire Fine Art Auction on September 24 with a guide price of £5,000-£10,000 but could make more.
Charles Hanson, owner of Hansons, said: “The forecast’s bright for this Whitehurst barometer. If the wind is blowing in the right direction it could go off the scale and fetch as much as £20,000.
“Karl was helping a client unload items from their car boot when he spotted it. No one knew this barometer existed. It’s unrecorded but we discovered it had been in the same Derbyshire family for more than 150 years.”
Karl said: “I knew straight away it could be by Whitehurst and that turned out to be the case. Finds like this blow you away. It was so unexpected.”
Only three surviving examples of Whitehurst angle barometers bearing earlier dates are known to exist. One, dated 1747, was sold in New York in 1985 while another, dated 1751, is displayed in a Derbyshire country house. Before the emergence of this new example, a total of 25 Whitehurst angle barometers were known, 11 being dated.
Whitehurst (1713-1788) was a founder member of the influential Lunar Society alongside Erasmus Darwin, and became a leading figure in the Midlands Enlightenment.
Karl Martin with the Whitehurst barometer. Picture: Adrian Kinton
Though he had only a sight formal education, he was brilliantly clever and his scientific innovations were ahead of their time.He pioneered angle barometers among other instruments, such as thermometers, and was a renowned clockmaker, a skill he learned from his father.
Though born in Congleton, Cheshire, he opened a business in Derby in 1736 where he soon distinguished himself. Besides other works, he made a clock for the town hall and was consulted in almost every undertaking in Derbyshire and its neighbouring counties when knowledge of mechanics, pneumatics and hydraulics was required.
He was a keen meteorologist and in the 1740s developed a 0-60 scale to express barometric pressure. He used this in preference to the conventional 28-31 inches of mercury. This anticipated the millibar, a metric unit for pressure used by weather researchers which was introduced more than 150 years later in 1909.The barometer up for auction is marked with Whitehurst’s 0-60 scale, has an inscribed brass reading plate and mercury tube and measures 90cm high and 73cm across.
The angle barometer, lot 555, is due to be sold on September 24 at Hansons, Heage Lane, Etwall, Derbyshire DE65 6LS. To find out more, email [email protected].
