Scale cheking in first - order triangulation nets

Abstract

National triangulation nets , if established by angular measurement, require several first-order sides, the lengths of which are exactly known as extension sides of one base extension net each. During the last century a variety of measuring devices had been used for measuring the base line (approximate length 2 - 8 km) with the highest possible accuracy. Depending on the technical development of that time, these measuring procedures not only varied considerably, but also lacked accuracy mainly because the systematic errors had not yet been found.