An instrument used to measure horizontal changes and elevations is a ________?

The instrument used to measure horizontal changes and elevations effectively is the dumpy level, also known as a builder's level. This instrument is designed specifically to establish a horizontal line of sight, allowing surveyors and construction workers to achieve accurate leveling over distances. The dumpy level operates using a telescope mounted on a leveling base, which can be adjusted and stabilized, ensuring precise measurements of both horizontal distances and elevation differences.

When utilizing the dumpy level, surveyors take readings from a staff or leveling rod placed at various locations. By setting the level at a known height and taking measurements, they can determine the elevation of other points relative to the baseline. This functionality makes the dumpy level essential for grading projects, where maintaining consistent elevation across a site is crucial for proper drainage and site usability.

Other options serve different specific purposes and do not provide the combination of horizontal and elevation measurement capabilities that the dumpy level offers. A surveying rod, for instance, is primarily a scale for height measurement, but lacks the mechanism for establishing a horizontal plane. Laser levels can also measure elevations but are typically used for specific tasks rather than providing comprehensive surveying capabilities. A tape measure is most suited for measuring linear distances rather than surveying elevations or establishing levels.