Evangelista Torricelli

] and having studied Ptolemy and seen almost everything of Tycho Brahe Kepler and Longomontanus finally forced by the many congruences came to adhere to Copernicus and was a Galileian in profession and sect". Barometer
Torricelli's chief invention was the mercury barometer which arose from solving a practical problem.

Evangelista Torricelli (Italian: [evandʒeˈlista torriˈtʃɛlli] [About this sound] pronunciation (help·info)) was an Italian physicist and mathematician best known for his invention of the barometer.