Leonardo da Vinci designed a clinometer for measuring the angle of a slope.
A clinometer, also called an inclinometer, determines the angle of elevation or depression relative to the horizontal. Leonardo’s interest in such instruments connected with surveying, architecture, military engineering, and the study of inclined surfaces.
The device should not be confused with a magnetic compass. A compass indicates direction, while a clinometer measures inclination. A level checks whether a surface is horizontal, but a clinometer can quantify a slope’s angle.
Leonardo’s notebooks contain many measuring devices because his engineering work depended on translating physical observations into geometry. Later clinometers became important in construction, mining, navigation, and field surveying.