A barometer is an instrument that measures atmospheric pressure.
It was during the 17th century that a series of experiments conducted by Italian scientist Evangelista Torricelli resulted in the invention of a basic barometer.
Torricelli was the first to notice that air pressure changes, related to weather changes, indeed caused the water level to rise and fall within a 35 foot tube experiment he set up within his home. He later used mercury in it.
The barometer utilizes the principle that as atmospheric pressure pushes down on the surface of the mercury in the cistern, the mercury in turn, pushes up with an equal pressure in the glass tube.
It wasn’t until about the year 1670 that barometers began to be used as a weather instrument in homes since 1670.
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