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Compensated barometer
Compensated barometer

Compensated barometer

Datec 1930s
Object number00028677
NameBarometer
MediumCopper alloy, tin, glass, paper, ink
DimensionsOverall: 118 x 118 x 51 mm, 1.1 kg
ClassificationsTools and equipment
Credit LineANMM Collection Gift from Dorothy Sharp
DescriptionThis compensated barometer was manufactured by T Wheeler Scientific Instruments Ltd in the 1930s. The barometer is marked in inches from 24 to 31, measuring up to 6,000 feet. Marked 'compensated,' this barometer is not influenced by changes in temperature.HistoryThe basic cause of weather lies in the property of a gas to rise when heated. As air is a gas, when it is warmed by the sun or by a large hot area like a desert, it rises, producing an area of low pressure. Colder, denser, higher pressure air from the surrounding area rushes in to take its place causing wind. This action causes variations in the atmospheric pressure at sea level. To the navigator, the atmospheric pressure in the ship's vicinity is the most important guide to the likely behaviour of the weather in the immediate future, and a barometer is one of the most accurate means of studying this pressure change. SignificanceThis compensated aneroid barometer, first patented in France in the 1840s, is an example of one of the earlier weather gauges available to a ship's master. Barometers remain an essential instument for mariners today.