Which of the following is a common tool used in land surveying?

A compass is a fundamental tool in land surveying that is used to determine directions relative to the Earth's magnetic poles. It consists of a magnetized needle that can pivot freely, aligning itself with the Earth's magnetic field. Surveyors use compasses to establish bearings and to help orient themselves in the field when taking measurements of land. This is crucial for accurately plotting boundaries and navigating the terrain.

In contrast, the other tools listed serve different purposes and are not typically associated with land surveying. An anemometer measures wind speed, a seismograph detects and records earthquakes, and a thermometer measures temperature. While all four tools are valuable in various scientific fields, only the compass is directly related to the practice of land surveying, making it the correct answer in this context.