A barometer measures atmospheric pressure. Evangelista Torricelli built the first mercury barometer in 1643-44, filling a glass tube with mercury and inverting it into a dish, and correctly concluded that the changing height of the mercury column tracked changes in the weight of the air above it.
Facts
Invented Year Operating PrincipleA column of mercury in a sealed tube is balanced against the weight of the atmosphere pressing on an open mercury reservoir, so the mercury column rises and falls as air pressure changes. 1 Operating RangeAverage atmospheric pressure varies between about 940 and 1040 hectopascals (millibars) at sea level; mercury barometers typically read between about 670 and 800 millimeters of mercury. 1 Open Questions
ResolutionNot stated as a numeric figure in the cited source.
No explicit resolution or precision figure is given by the cited source for the barometer. Classification
Instrument ClassMeasurement or Metrology Instrument 1 Connections
Invented By
Built the first mercury barometer in 1643 to 44, following a suggestion from Galileo, producing the first sustained vacuum.
Source Mercury Barometer (Britannica)
Used In
Source Mercury Barometer (Britannica)
Source Mercury Barometer (Britannica)
Sources
1. Barometer (Wikipedia)
WikipediaIntroduction
A barometer is a scientific instrument that is used to measure air pressure.
Mercury barometers section
Mercury in the tube adjusts until the weight of it balances the atmospheric force exerted on the reservoir.
Introduction / Mercury barometers section
The average atmospheric pressure on the Earth's surface varies between 940 and 1040 hPa (mbar).
Lede, instrument class
A barometer measures atmospheric pressure.
View the Source 2. Mercury Barometer (Britannica)
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