und Phys. Geographie', 1829, s. 5) gives
1/20742d, as the mean of seven measures. Respecting the influence of great
differences of longitude on the polar compression, see 'Bibliotheque
Universelle', t. xxxiii., p. 181, and t. xxxv., p. 50: likewise
'Connaissance des Tems', 1829, p. 290. From the lunar inequalities alone,
Laplace ('Exposition du Syst. du Monde', p. 229) found it, by the older
tables of Burg, to be 1/3245th; and subsequently, from the lunar
observations of Burckhardt and Bouvard, he fixed it at 1/299.1th ('Mecanique
Celeste', t. v., p. 13 and 43).
In accordance with this, the polar radius is 10,938 toises (69,944 feet), or
about 11 1/2 miles, shorter than the equatorial radius of our terrestrial
spheroid. The excess at the equator in consequence of the curvature of the
upper surface of the globe amounts, consequently, in the direction of
gravitation, to somewhat more than 4 3/7th times the height of Mont Blanc,
or only 2 1/2 times the probable height of the summit of the Chawalagiri, in
the Himalaya chain. The lunar inequalities (perturbation in the moon's
latitude and longitude) give according to the last investigations of
Laplace, almost the same result for the ellipticity as the measurements of
degrees, viz.
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