text: A mercury barometer is one of the classic uses of static pressure head. Such barometers are an enclosed column of mercury standing vertically with gradations on the tube. The lower end of the tube is bathed in a pool of mercury open to the ambient to measure the local atmospheric pressure. The reading of a mercury barometer (in mm of Hg, for example) can be converted into an absolute pressure using the above equations.
  If we had a column of mercury 767 mm high, we could calculate the atmospheric pressure as (767 mm)•(133 kN/m) = 102 kPa. See the torr, millimeter of mercury, and pascal (unit) articles for barometric pressure measurements at standard conditions.