Which tool is designed to measure horizontal angles only?

The builder's level, also known as a dumpy level, is specifically designed for measuring horizontal angles. It is a surveying instrument that helps establish a level line or plane across a site by using a telescope that can be rotated horizontally to take readings. This tool allows construction professionals to accurately set and transfer grade levels, making it essential for ensuring that structures are built correctly and maintaining proper drainage.

In contrast, a laser level emits a laser beam to provide a reference line that can be used for both horizontal and vertical alignment. A digital level is equipped with sensors that provide accurate readings of level and slope but are not solely for measuring horizontal angles. A spirit level, while useful for determining if a surface is level, does not measure angles; it relies on bubble indicators to assess levelness. Thus, the builder's level stands out as the appropriate tool for the specific task of measuring horizontal angles.