Images(4)

Case for Aneroid barometer

Date1800-1899

Object number00050194

NameCase

MediumTimber, glass, bronze

DimensionsOverall: (Empty)72 x 165 x 175 mm, 827 g

ClassificationsTools and equipment

Credit LineANMM Collection

Terms

DescriptionResponding to changes in air pressure acting on a sealed metal chamber which moved a needle on a dial, the aneroid barometer was a robust instrument for measuring changes in air pressure. It was particularly useful for predicting changes in weather. The term aneroid comes from the Greek meaning "without liquid" and the aneroid barometer offered significant advantages over the earlier technology of mercury barometers. HistoryThe barometer was developed in the second half of the 17th century. This consisted of a glass tube containing mercury. The mercury rose or fell with changes in atmospheric pressure and it was soon realised that these changes were associated with improving or worsening weather. Barometers were increasingly available for domestic use by 1700. A glass tube filled with mercury, even when mounted on a rigid wooden backplate, was a fragile object vulnerable to damage by the motion of a ship at sea. But by restricting the bore of the glass tube, the rate of movement of the mercury could be slowed, reducing the risk of the tube being broken. The first marine barometers were produced in the 1770s and were reasonably standardised by the early 19th century. The first commercially viable aneroid barometer was produced in 1844 by Lucien Vidie in France. This worked by air pressure acting on a sealed metal chamber, the movement operating a needle on a dial. The term aneroid comes from the Greek meaning "without liquid" and the aneroid barometer offered significant advantages over the earlier technology of mercury barometers. Edward John Dent (1790-1853) is most famously remembered as a maker of fine clocks, watches and chronometers in the 19th century. From 1830 to 1840 he was in partnership with John Roger Arnold, one of the leading chronometer makers in London. Dent's work was highly regarded and his firm produced the Standard Clock for the Greenwich Observatory (being the universal reference for Greenwich Mean Time until replaced by an electronic clock in 1946), and the great clock (Big Ben) for the Houses of Parliament. After his death the company was continued by his successors under various names, all retaining the name 'Dent'.SignificanceThe invention of the aneroid barometer in the 19th century represented a significant step in the evolution of the barometer and went some way to assisting mariners to predict changes in weather.