The construction of a geodetic arc is one of the largest in the 19th century. the first half attempts to explore and to determine the size and shape of the Earth. Professor of the University of Tartu, astronomer Friedrich Georges Wilhelm Struve developed a methodology for integrating the land of a meridian - a semicircle connecting the earth northern and southern poles, - to measure the bow. He formed the triangulation (triangular) chain, which consists of 259 triangles with special vertices. Southwest Arc lasted from the Danube River to the Black Sea to the Fugennes Arctic Ocean. The bow is intersecting current states like Norway, Sweden, Finland, Estonia, Latvia, Lithuania, Belarus, Ukraine and Moldova.
XIX century it was the most accurately measured and longest arc of the meridian. His measurement results yet The century has been used to calculate and correct the Earth's ellipsoid - not completely regular in shape ball - parameters. Based on this work by FGW Struv, in 1888, Earth's meridian length Geodesist A. Bonsdorf has calculated.
Currently ten European countries are protected by 34 differently marked Struve geodetic arcs points, three of them in the territory of Lithuania - in the villages of Meshkūniai, Paliepukiai and Gireišiai. Struve geodetic arc is one of the four values of global significance in Lithuania - in 2005 he was Included in the UNESCO World Heritage List. A tower stood at Mount Mayoko in the Molėtai district, The part of the Struve geodetic arc, which measured the sea level.