BELARUS

A nice UNESCO cover from Belarus, depicting a miniature sheet issued in 2017 on topic "Struve Geodetic Arc". The Struve Geodetic Arc is a chain of survey triangulations stretching from Hammerfest in Norway to the Black Sea, through ten countries and over 2,820 km, which yielded the first accurate measurement of a meridian arc. The chain was established and used by the German-born Russian scientist Friedrich Georg Wilhelm von Struve in the years 1816 to 1855 to establish the exact size and shape of the earth. At that time, the chain passed merely through three countries: Norway, Sweden and the Russian Empire. The Arc's first point is located in Tartu Observatory in Estonia, where Struve conducted much of his research. In 2005, the chain was inscribed on the World Heritage List as a memorable ensemble of the chain made up of 34 commemorative plaques or built obelisks out of the original 265 main station points which are marked by drilled holes in rock, iron crosses, cairns, others. Measurement of the triangulation chain comprises 258 main triangles and 265 geodetic vertices. The northernmost point is located near Hammerfest in Norway and the southernmost point near the Black Sea in Ukraine. This inscription is located in ten countries, the second most of any UNESCO World Heritage after the Ancient and Primeval Beech Forests of the Carpathians and Other Regions of Europe.

ESTONIA

A nice Unesco cover from Estonia, depicting a miniature sheet issued in 2011 on topic "Struve Geodetic Arc".
The Struve Arc is a chain of survey triangulations stretching from Hammerfest in Norway to the Black sea, through 10 countries (including Moldova, of course) and over 2,820 km. These are points of a survey, carried out between 1816 and 1855 by the astronomer Friedrich Georg Wilhelm Struve, which represented the first accurate measuring of a long segment of a meridian. This helped to establish the exact size and shape of the planet and marked an important step in the development of earth sciences and topographic mapping. It is an extraordinary exemple of scientific collaboration among scientists from different countries and of collaboration betweeen monarchs for a scientific cause.

MOLDOVA

A nice Unesco cover from Moldova, depicting a miniature sheet issued in 2016 on topic "Struve Geodetic Arc".
The Struve Arc is a chain of survey triangulations stretching from Hammerfest in Norway to the Black sea, through 10 countries (including Moldova, of course) and over 2,820 km. These are points of a survey, carried out between 1816 and 1855 by the astronomer Friedrich Georg Wilhelm Struve, which represented the first accurate measuring of a long segment of a meridian. This helped to establish the exact size and shape of the planet and marked an important step in the development of earth sciences and topographic mapping. It is an extraordinary exemple of scientific collaboration among scientists from different countries and of collaboration betweeen monarchs for a scientific cause.