The historical aspects of the development of geodesic instrument construction: Instruments for geometric leveling

Abstract

Leveling is the most common type of topographic-geodetic work, which is performed to determine elevations between points on the physical surface of the Earth or their heights relative to the accepted starting surface. Geometric leveling is the most accurate method of all leveling methods. In geometric leveling, a horizontal sighting beam is used, which is obtained mainly with the help of geodetic devices, which are called levels. In general, this type of work is performed with equipment, which includes a tripod, a pair of rails, and a level, which, of course, is the main part of the set. An optical level is the simplest and most common geodetic device designed to measure elevations of one point of terrain over another. Their diversity is due to a wide range of areas of application: from construction and installation of equipment to the creation of state leveling networks. Devices are used to determine the difference in height of points. According to accuracy, these devices are divided into technical levels, accurate, and high-precision levels. Most modern optical levels are equipped with an automatic compensator (for automatic setting of the sighting axis in a horizontal position), have a direct image, and a horizontal limb (the price of a division of 1°). Some models of levelers have a special device to protect the compensator mechanism from accidental shocks and damage when carrying the leveler in a case. Readings are taken using special leveling rails. The difference between the readings gives an excess on the terrain.In this work, the evolutionary development of geodetic instrumentation is analyzed from a historical perspective using the example of devices for performing geometric leveling: from the Roman trowel to the automatic optical leveler with a compensator and internal focusing. The importance of constructive improvements of geodetic instruments and their influence to the development of modern electronic levels is emphasized.