ABSTRACT
This chapter is devoted to description of levels and covers principles from the classic bubble-based mechanical levels to the most advanced microelectromechanical systems (MEMS) technology, which enables automatic levels including modern laser plane systems. The cornerstone of any surveyor's leveling instrument is a device that creates a horizontal line, or a surface perpendicular to a plumb line. Ancient pendulum and hydraulic leveling systems have been useful for several thousand years. However, those systems have reached the limits of their technological accuracy. Earlier, a tubular level was used with diopters, known from Ancient Greece. The direct image realization of the Kepler telescope was a final step toward modern devices. Modern dumpy levels have various appliances to supervise the tubular level bubble position. The elementary of them is a clapper-type mirror. Automatic levels compensators have magnetic or air dampers. The influence of electromagnetic industrial fields and the Earth's magnetic field may affect the magnetic damper levels.
