Gerlach leveller

A leveller is a land survey instrument allowing measurement of the difference in height (geometric levelling) between points in the field. The instrument has the form of a horizontal tube with a scope and a spirit level, which allows horizontal positioning of the device. A leveller is mounted on a tripod base, on which the whole device is mounted on a tripod. The altitude difference read out involves observing values, using the horizontal leveller, on the so-called level staffs set vertically in the targeting axis of the instrument. Modern, automatic levellers do not require very precise manual levelling, as they are equipped with a mechanic/optical system called the compensator. Its purpose is to maintain a horizontal cause of the targeting axis in case of minuscule deviations of the instrument. Manufacturer: Specjalna Fabryka Instrumentów Geodezyjnych i Rysunkowych G. Gerlach, 1920s – 1930s Inv. No.: MIM906/XI-47 Model prepared on the basis of photogrammetric measurements. Licence: CC BY-NC-SA