What is the primary use of a level instrument?

The primary use of a level instrument is to determine elevations accurately. Level instruments are essential tools in surveying and construction, allowing professionals to find the relative heights of different points on a site. By establishing a horizontal line of sight, a level can help ensure that structures are built to the correct elevation specified in plans and prevent issues related to drainage and grading.

While calculating slope, measuring horizontal distances, and marking locations might be tasks that a surveyor engages in, they are not the primary function of a level instrument. The precise measurement of elevations is crucial for tasks such as foundation setting, road construction, and topographic mapping, making it the key purpose of a level instrument.