What device measures atmospheric pressure by balancing a column of mercury?

The device that measures atmospheric pressure by balancing a column of mercury is indeed the mercury barometer. This instrument operates based on the principle that the weight of a column of mercury is balanced against atmospheric pressure. A glass tube filled with mercury is inverted into a reservoir of mercury, creating a vacuum at the top of the tube. The height of the mercury column in the tube then indicates the atmospheric pressure, usually measured in millimeters of mercury (mmHg).

Mercury barometers are highly accurate for measuring air pressure, and they have been used historically in meteorology to forecast weather based on changes in atmospheric pressure.

Other devices mentioned have different mechanisms or purposes. For instance, an aneroid barometer uses a sealed metal chamber that expands and contracts with pressure changes rather than a mercury column. A digital pressure gauge typically measures physical pressure in various applications but not specifically in the manner of balancing a mercury column. A manometer, while it measures pressure difference, often involves measuring liquid columns other than mercury and is used primarily in laboratory settings rather than for atmospheric pressure measurement.