A cathetometer is a scientific instrument that is used to measure vertical distances or heights. It is commonly used in physics, engineering, and cartography. In some fields, it may also be referred to as a levelling instrument or a height gauge. Other synonyms for cathetometer include clinometer, square, or spirit level. These similar tools may be used for similar tasks, but each has its unique benefits and limitations. Choosing the right tool for the job depends on the specific requirements and preferences of the user. Whatever the name or design, these measuring tools are essential for accurate and reliable vertical measurement in a variety of scientific and technological applications.