John Fillmore Hayford

John Fillmore Hayford ( born May 19, 1868 in Rouses Point, New York, † March 10 1925 in Evanston, Illinois ) was an American engineer and surveyor, who is known primarily for his " Hayford ellipsoid " of 1909.

Hayford was the first of the mass distribution of the interior taken into account in determining the exact figure of the earth - namely, the hypothesis of isostasy to a depth of about 100 km. The continents meet this floating balance, but only at about 90 percent, so the data Hayford Erdachsen differ despite the good methodology by about 300 meters from the modern values ​​. This corresponds to 0.04 per thousand of the earth's radius, which until then had never reached, and was 3 times more accurate than the then prevalent Bessel ellipsoid.

The International Union of Geodesy and Geophysics ( IUGG ) adopted at its Congress in 1924 Hayford results as the International ellipsoid 1924. However, since 1967 and 1981, slightly better International ellipsoids were set, it is called since then most of the " Hayford ellipsoid ".

After Hayford a lunar crater was named.

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