From Mary Bellis,
Your Guide to Inventors.
FREE Newsletter. Sign Up Now!

Barometer - Pronunciation: [b u rom´ u t u r] - a barometer is an instrument for measuring atmospheric pressure. Two common types are the aneroid barometer and the mercurial barometer (invented first). Evangelista Torricelli invented the first barometer, known as the "Torricelli's tube".

Biography - Evangelista Torricelli

Evangelista Torricelli was born October 15, 1608, in Faenza, Italy and died October 22, 1647 in Florence, Italy. He was a physicist and mathematician. In 1641, Evangelista Torricelli moved to Florence to assist the astronomer Galileo.

The Barometer

It was Galileo that suggested Evangelista Torricelli use mercury in his vacuum experiments. Torricelli filled a four-foot long glass tube with mercury and inverted the tube into a dish. Some of the mercury did not escape from the tube and Torricelli observed the vacuum that was created.

Evangelista Torricelli became the first scientist to create a sustained vacuum and to discover the principle of a barometer. Torricelli realized that the variation of the height of the mercury from day to day was caused by changes in the atmospheric pressure. Torricelli built the first mercury barometer around 1644.

Evangelista Torricelli - Other Research

Evangelista Torricelli also wrote on the quadrature of the cycloid and conics, the rectifications of the logarithmic spiral, the theory of the barometer, the value of gravity found by observing the motion of two weights connected by a string passing over a fixed pulley, the theory of projectiles and the motion of fluids.

Lucien Vidie - Aneroid Barometer

In 1843, the French scientist Lucien Vidie invented the aneroid barometer. A aneroid barometer "registers the change in the shape of an evacuated metal cell to measure variations on the atmospheric pressure." Aneriod means fluidless, no liquids are used, the metal cell is usually made of phosphor bronze or beryllium copper.

Related Instruments

An altimeter is an aneroid barometer that measures altitude. Meteorologists use an altimeter that measures the altitude with respect to sea level pressure.

A barograph is an aneroid barometer that gives a continuous reading of atmospheric pressures on graph paper.