Answer:
a barometer is used to measure atmospheric pressure, and a manometer is used to measure gauge pressure.
Step-by-step explanation:
A barometer measures air pressure at any locality with sea level as the reference.
However, a manometer is used to measure all pressures especially gauge pressures. Thus, if the aim is to measure the pressure at any point below a fluid surface, a barometer is used to determine the air pressure. The manometer may now be used to determine the gauge pressure
The algebraic sum of these two values gives the absolute pressure.