A practical manual introduces atmospheric principles and explains how air pressure varies, then shows methods for using barometric measurements to determine altitude. It describes the design and mechanics of aneroid instruments, gives guidance on selecting and operating them, and provides worked examples and systematic procedures for field measurements. The book includes supporting reference tables—altitude conversions, logarithms, metric tables, corrections for mercurial instruments, and boiling-point correspondences—and offers advice on instrument care and interpretation of readings for both meteorological and surveying purposes.