As Hayford ellipsoid that Erdellipsoid is called, the John Fillmore Hayford (1868-1925), an American surveyor, 1905-1909, calculated from global survey data. Hayford Erddimensionen

Are compared to other ellipsoids to find about the Bessel ellipsoid of 1841, in the table of important reference ellipsoid. From the international geoscientific umbrella organization IUGG in 1924 they were taken over as the International ellipsoid 1924.

In contrast to the older, optimal for Eurasia Bessel ellipsoid, the data of numerous surveying networks in the area of North America are included, to a lesser extent also those of other continents and several island groups. Moreover, the data of geophysical reduction according to the hypothesis of isostasy were subjected to such that the Lotabweichungs influences could be reduced to the deep crust.

This Hayford Ellipsoidachsen are largely adjusted by a continental geological effect, which has led the Bessel and other early ellipsoids with an axis shortening from an ideal Erdellipsoid with global data distribution.

Since 1967, the Lucerne ellipsoid and 1980 with the GRS 80 each a more accurate " international ellipsoid " was defined, it was common place "International Ellipsoid (1924 ) " simply by " Hayford ellipsoid " to speak.

After more modern results Hayford equatorial axis at 251 m is too long and its too shallow flattening at the poles to 90 m. One of the reasons for this is the fact that in Eurasia the great mountains mainly run east-west, in America, however, north-south.