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The first known arc 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. In the early 8th century, Yi Xing performed a similar survey.
The Struve Geodetic Arc was one of the most precise and largest projects of earth measurement at that time. In 1860 Friedrich Georg Wilhelm Struve published his Arc du méridien de 25° 20′ entre le Danube et la Mer Glaciale mesuré depuis 1816 jusqu’en 1855. The flattening of the earth was estimated at 1/294.26 and the earth's equatorial ...
Eratosthenes described his arc measurement technique, [14] in a book entitled On the Measure of the Earth, which has not been preserved. However, a simplified version of the method has been preserved, as described by Cleomedes. [15]
The arc measurement of Delambre and Méchain was a geodetic survey carried out by Jean-Baptiste Delambre and Pierre Méchain in 1792–1798 to measure an arc section of the Paris meridian between Dunkirk and Barcelona. This arc measurement served as the basis for the original definition of the metre. [1]
The Arc's first point is located in Tartu Observatory in Estonia, where Struve conducted much of his research. [1] Measurement of the triangulation chain comprises 258 main triangles and 265 geodetic vertices. [2] The northernmost point is located near Hammerfest in Norway and the southernmost point near the Black Sea in Ukraine.
As one degree is 1 / 360 of a circle, one minute of arc is 1 / 21600 of a circle – such that the polar circumference of the Earth would be exactly 21,600 miles. Gunter used Snellius's circumference to define a nautical mile as 6,080 feet, the length of one minute of arc at 48 degrees latitude. [24]
After the Struve Geodetic Arc measurement, it was resolved in the 1860s, at the initiative of Carlos Ibáñez e Ibáñez de Ibero, who would become the first president of both the International Geodetic Association and the International Committee for Weights and Measure, to remeasure the arc of meridian from Dunkirk to Formentera and to extend ...
A meridian arc of Jean Picard was extended to a longer arc by Giovanni Domenico Cassini and his son Jacques Cassini over the period 1684–1718. [6] The arc was measured with at least three latitude determinations, so they were able to deduce mean curvatures for the northern and southern halves of the arc, allowing a determination of the ...