Barometric pressure was discovered in about 1644 when physicist and inventor Evangelista Torricelli invented the first mercury barometer. Torricelli was an assistant to Galileo Galilei who suggested that Torricelli try using mercury in his vacuum experiments. As Torricelli experimented, he realized the height of the mercury varied from day to day because of changes in atmospheric pressure, thus discovering the principle of the barometer.Continue Reading
Italian astronomer Gasparo Berti and French scientist René Descartes also experimented with atmospheric pressure slightly before Torricelli's discovery, but they did not solve the problem. In 1646 Blaise Pascal and Pierre Petit replicated Torricelli's experiments. Pascal carried the experiments one step further by studying barometric measurements taken at various heights above sea level. The barometer showed lower numbers the higher it went, proving that air weighs less at higher altitudes.
Further experiments by Otto von Guericke resulted in the first air pump, which Robert Boyle used to study the physiological effects of reduced barometric pressure. Another big step forward in the study of barometric pressure came in 1843 when French physicist Lucien Vidie invented the first aneroid barometer, which measured barometric pressure without using any liquids, instead registering air pressure changes by analyzing the shape of a metal cell made of phosphor bronze or beryllium copper.Learn more about Inventions