Comprising two glass tubes, one closed at the top and other tube open. Their lower ends are drawn out and connected together by 1meter of rubber tubing. Both tubes are mounted on sliding brackets which may be locked in any position on the metal supporting rods. Seasoned wood board approximately 44″ high carries a meter scale graduated from 0 to 100 cm fitted on heavy iron base with levelling screws. Supplied without mercury and rubber tube.