| A torr is a physical unit of measure for pressure. The Torr is named after Italian scientist Evangelista Torricelli (1608-1647). One torr is defined as the pressure exerted by a one millimeter column of mercury:
1 torr = 1 mm Hg = 1/760 atm = 144.32 Pa
The torr is commonly used for measuring very low pressures (vacuum science). | 
