What is Abuey Level in Geography?

Abuey Level in Geography refers to an instrument of surveying, made up of a spirit level mounted over a sighting-tube. Used in measuring the angle of inclination of a line joining an observer to another distant point. If the linear distance between the two points is measured, their difference in height can be calculated by knowing the tangent ratio. This provides a convenient and rapid field-survey method when an accuracy of ± a half-degree is sufficient.