Why instrument is called spherometer?

A spherometer is called so because it is designed to measure the curvature of spherical surfaces. The term "sphero-" refers to a sphere, while "-meter" indicates a measuring device. By using a three-point support system and a central measuring probe, a spherometer can accurately determine the radius of curvature of a spherical object. This makes it particularly useful in fields such as optics and engineering where spherical surfaces are common.