Grade Measurement (Paperback)

High Quality Content by WIKIPEDIA articles! Grade measurement is the geodetic determination of the local radius of curvature of the figure of the Earth by determining the difference in astronomical latitude between two locations on the same meridian, the metric distance between which is known.The first known grade measurement was performed by Eratosthenes (240 BC) between Alexandria and Syene in what is now Egypt, determining the radius of the Earth with remarkable correctness. The Dutch geodesist Snellius ( 1620) repeated the experiment between Alkmaar and Bergen op Zoom using more modern geodetic instrumentation.