sentences:  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/m³) = 102 kPa.