What is a barometer? This technical term is commonly referred to as a device for measuring atmospheric pressure. The most widely used barometers are of two types. The mercury barometer is used to measure atmospheric pressure mainly at meteorological stations.
It is more cumbersome, but it also gives greater measurement accuracy, which is why scientists prefer it. This type of barometer was invented and built by the Italian scientist Evangelista Torricelli in 1644. The principle of its operation is the balancing of a column of mercury with a column of atmospheric air. Due to the high density of mercury, the height of the column is very small (when they say that atmospheric pressure is 760 millimeters of mercury, this means that atmospheric air at the measurement point is pressed with the same force).
Aneroid barometer is a more complex device. Although the idea of the device was expressed almost simultaneously with the invention of mercurybarometer (this was done in the same seventeenth century by the German scientist Gottfried Leibniz), but the great German's idea was put into practice only two hundred years later. In 1847, the talented French engineer Lucien Vidi created the world's first aneroid barometer. What is the principle of its action?
The barometer received the name "aneroid", that is, anhydrous. With this term, the creator wanted to emphasize that no liquid is used in the device, unlike a mercury barometer, where liquid metal is the sensitive element. slightly shrinks or expands. The system of levers sets in motion an arrow, which on a specially graduated scale indicates atmospheric pressure in millimeters of mercury.
It would seem that nothing complicated, and an aneroid barometer could have been created at the level of technological development both from the time of Torricelli and before him. Why didn't this happen? Most likely, a combination of several factors played a role here. The first and main thing is the lack of need for such a device at that time. In fact, meteorology as a science was only in its infancy, and the dependence of small fluctuations in atmospheric pressure and weather was only realized by scientists of that time. In addition, the lack of a suitable material for the corrugated box may have played a role (it must have acceptable elasticity and not stretch during a longoperation).
As science developed, both the first and second circumstances ceased to prevent the creation of an aneroid.
After the invention of Luien Vidi, the aneroid barometer began to spread rapidly throughout private houses and apartments. There was even a peculiar fashion: the presence of this device in the house emphasized the social and intellectual status of the owner. Such a person, in modern terms, was considered "advanced".
As the international metric system (SI) was adopted by most countries, the graduation of the aneroid scale began to be supplemented by a scale where the pressure was indicated not only in millimeters of mercury (this is not a system unit), but also in pascals. There is also a graduation of the aneroid scale in bars. A bar is also a non-systemic unit, approximately equal to one atmosphere. Sometimes it is more convenient to measure pressure in bars than in millimeters of mercury or in system units.
However, the habit of measuring atmospheric pressure in millimeters of mercury turned out to be very strong. Even now, atmospheric pressure is reported in weather forecasts in these non-systemic units.
