Definition - What does Mercury Barometer mean?
A Mercury Barometer is a barometer with a glass tube that is closed on one end and open on the other side that is lowered in a mercury reservoir at the base. The mercury's weight in the tube creates a vacuum at the top known as a Torricellian Vacuum. The atmospheric force and pressure makes the mercury to adjust accordingly in the tube. The higher the atmospheric pressure is, the more pressure it will put on the mercury reservoir, forcing the mercury to rise up in the column. The atmospheric pressure in the Mercury Barometer can be measured in inches, feet or millimeters.
Petropedia explains Mercury Barometer
A Mercury Barometer is a special barometer that has a mercury filled base at the bottom and a tube with an open end and closed end dipped into it. The Mercury Barometer works under atmospheric pressure which makes the mercury in the reservoir to move up the tube. When the atmospheric pressure is low, the mercury drops to a lower level, with almost no pressure on the reservoir. When the atmospheric pressure is high, there is more force on the reservoir which makes the mercury to rise up in the tube. As the mercury rises, it creates a Torricellian vacuum at the top of the tube.