A theodolite is an instrument for making accurate and precise measurements of angles. It consists of a telescope mounted on swivels and a baseplate that has a scale for measuring the angle. In use, the theodolite is leveled and the telescope is used to sight a remote target. The angle is noted, and the telescope is swiveled to sight a second target. The angle is noted again, and the difference provides the measure of the angle between the targets. The technique is used for triangulation.