Millimeter of mercury or mmHg was a unit used to measure atmospheric pressure, measured on an instrument called a barometer or more advanced sensor. The atmospheric pressure of the planet Taurus II was measured at 70 mmHg. (TOS: "The Galileo Seven" ) The unit was also displayed on medical monitors measuring the blood circulation of a person among other vital signs. (TNG: "We'll Always Have Paris" , "The Neutral Zone" )