Abstract: There is provided a pressure measuring apparatus, useful as a barometer, comprising a first variable volume vessel containing a gas, said first vessel being extendable and retractable between a first end and a second end thereof, the pressure to be measured acting on said first vessel, a second variable volume vessel containing a substantially incompressible liquid, said second vessel being extendable and retractable between a first and a second end thereof, a means for indicating the pressure acting on said first vessel, a first member joined to said first end of said first vessel and a second member joined to said second end of said first vessel, said first end of said second vessel being joined to open of said members, said second end of said second vessel or said second vessel being joined to the other of said members, said indicating means communicating with the interior of one of said first vessel, said members being relatively movable toward and away from each other in parallel relationship, whereby a