Struve Geodetic Arc
The chain was made and used by the German-born Russian scientist Friedrich Georg Wilhelm von Struve in the years 1816 to 1855.  He did this to find the exact size and shape of the earth. At that time, the chain passed through two countries: Union of Sweden-Norway and the Russian Empire. The Arc's first point is in Tartu Observatory.  This is where Struve did much of his research.