Measurement of Atmos. Pressure
	q Mercury Barometers – Height of mercury indicates downward force of air pressure – Three barometric corrections must be made to ensure homogeneity of pressure readings – First corrects for elevation, the second for air temperature (affects density of mercury), and the third involves a slight correction for gravity with latitude q Aneroid Barometers – Use a collapsible chamber which compresses proportionally to air pressure – Requires only an initial adjustment for elevation