Compact portable digital multimeter for instantaneous measuring of height differences independently of visibility

A device for instantaneous and exact measurement of height differences and topographical leveling in conditions of difficult visibility as in the night, fog, high thermal refraction of the atmosphere, galleries, tunnels and underground passages of mines, in fields with obstacles such as slopes, etc, said device comprising a single small portable water tank to be placed at a location the height of which is to be measured, said water tank being open to atmospheric pressure, a pressure transducer to be placed at a reference location, a single hose connecting said tank with said pressure transducer, valve means for expulsion of air from said hose, said pressure transducer comprising an elastic diaphragm subjected to hydrostatic pressure transmitted by said hose and a strain gauge bridge coupled with said diaphragm to generate a voltage signal proportional to pressure, and electronic circuit means for amplifying and displaying said voltage signal, said circuit means comprising an operational amplifier for amplifying said voltage signal and digital voltmeter for displaying the amplified signal, said digital voltmeter being calibrated to read in terms of height of location to be measured.