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Definition: barometer from Dictionary of Energy

Measurement. an instrument for measuring atmospheric pressure; used in determining height above sea level and predicting changes in the weather.

barometer

From The Columbia Encyclopedia
(bӘrŏm'ӘtӘr), instrument for measuring atmospheric pressure. It was invented in 1643 by the Italian scientist Evangelista Torricelli, who used a column of water in a tube 34 ft (10.4 m) long. This inconvenient water column was soon replaced by mercury, which is denser than water and requires a tube about 3 ft (0.9 m) long. The mercurial barometer consists of a glass tube, sealed at one end and filled with pure mercury. After being heated to expel the air, it is inverted in a small cup of mercury called the cistern. The mercury in the tube sinks slightly, creating above it a vacuum (the Torricellian vacuum). Atmospheric pressure on the surface of the mercury in the cistern supports the column in the tube, which varies in height with variations in atmospheric pressure and hence with changes in elevation, generally decreasing with increases in height above sea level. Standard sea-level pressure is 14.7 lb per sq in. (1,030 grams per sq cm), which is equivalent to a column of mercury 29.92…
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Full text Article barometer

From Philip's Encyclopedia
Instrument for measuring atmospheric pressure. There are two basic types. A mercury barometer has a vertical column of mercury, whose length alters with changes in atmospheric pressure. An aneroid barometer has a chamber containing a partial vacuum, and the chamber changes shape with shifts in…
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The barometer - an instrument for measuring atmospheric pressure - was invented by the Italian philosopher and mathematician Evangelista Torricelli in 1643-4. Torricelli discovered that the height of mercury in a glass tube immersed upside down in a cistern of mercury is dependent on atmospheric…
| 1,347 words
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Full text Article barometer

From The Columbia Encyclopedia
(bӘrŏm'ӘtӘr), instrument for measuring atmospheric pressure. It was invented in 1643 by the Italian scientist Evangelista Torricelli, who used a column of water in a tube 34 ft (10.4 m) long. This inconvenient water column was soon replaced by mercury, which is denser than water and requires a tube…
| 333 words
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Full text Article barometer

From The Penguin Dictionary of Physics
An instrument for measuring atmospheric pressure. Mercury barometers consist of a glass tube about 80 cm long, closed at one end. The tube is filled with mercury and then placed, open end downward, in a reservoir of mercury. As the atmospheric pressure changes, the level of the mercury changes and, …
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Full text Article BAROMETER

From Gaither's Dictionary of Scientific Quotations
No biographical data available We often hear it said that however reliable the fluctuations of the barometer may be in other sections, as indicating the approach of storms, upon the Pacific Coast some exceptional rule or, rather, no rule exists, and that the variations of the barometer really…
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Full text Article barometer

From Britannica Concise Encyclopedia
Device used to measure atmospheric pressure . Because atmospheric pressure changes with distance above or below sea level, a barometer can also be used to measure altitude. In the mercury barometer, atmospheric pressure balances a column of mercury , the height of which can be precisely measured. …
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Full text Article barometer

From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide
Instrument that measures atmospheric pressure as an indication of weather. Most often used are the mercury barometer and the aneroid barometer. In a mercury barometer a column of mercury in a glass tube, roughly 0.75 m/2.5 ft high (closed at one end, curved upwards at the other), is…
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Full text Article Global Corruption Barometer

From The A to Z of Corporate Social Responsibility
→ Corruption , Transparency International www.transparency.org → Transparency International's (TI) Global Corruption Barometer (the Barometer) presents the results of a public opinion survey carried out in many low, middle, and high-income countries. The Barometer seeks to understand how and in what…
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Full text Article barometer

From The American Heritage Student Science Dictionary
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Full text Article barometer

From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide
barometer
| 96 words , 1 image
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