What instrument is essential for measuring vertical angles in surveying?

The essential instrument for measuring vertical angles in surveying is a theodolite. A theodolite is specifically designed for precise angle measurements in both the horizontal and vertical planes. It uses a rotating telescope to measure angles with high accuracy, making it a fundamental tool in surveying tasks where vertical angle determination is critical, such as in the construction of buildings, bridges, and other engineering projects.

An inclinometer is primarily used for measuring the angle of inclination or slope of an object relative to a reference plane, often in applications related to geotechnical engineering or for measuring tilt in structures. While it provides valuable information about angles, it is not the primary instrument used for surveying vertical angles like a theodolite.

A spirit level is employed to determine the horizontal plane in small-scale measurements or construction applications. It does not measure angles and therefore cannot fulfill the role needed for measuring vertical angles.

A total station is a versatile instrument that combines the features of a theodolite with an electronic distance measuring device. While it can measure vertical angles, its primary function is broader, encompassing distance measurements and coordinate calculations. It is certainly advanced in its capabilities, but the classic instrument dedicated solely to vertical angle measurement remains the theodolite.