they are all at right angles to be radius of the earth.”[1] Fig. 44 shows this on a meridional section between the pole (P) and the equator (A). The interrupted line concave to the pole is the line of force of gravity or plumb-line of the place O. C is the centre point of the earth.
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Fig. 44.—Level-surfaces and curved plumb-line.
Now the centre of buoyancy of a floating body is situated in the centre of gravity of the medium displaced; that of its weight, on the contrary, in its own centre of gravity; and the direction of each force is at right angles to the horizontal plane at the point of application. Their directions are thus not in opposition, but give a small resultant, which, if the buoyancy point lies under the centre of gravity, is directed towards the equator. Both forces are not perpendicular to the horizontal plane at the surface of the block, since its centre of gravity lies far below, but are somewhat bent in the same direction,[2] the buoyancy, however, more than the weight of the block. These principles must apply to all floating bodies, the centre of gravity of which lies above the buoyancy point, and in the same way the forces must have a resultant directed towards the pole, if the centre of gravity lies under the buoyancy point; the principle of Archimedes is then only strictly correct on a revolving earth if both points coincide.”
- ↑ W. Köppen, “Ursachen und Wirkungen der Kontinentalverschiebungen und Polwanderungen,” Peterm. Mitt., pp. 145–149 and 191–194, 1921; see especially page 149.—“Über Änderungen der geographischen Breiten und des Klimas in geologischer Zeit,” Geografiska Annaler, pp. 285–299, 1920.—“Zur Paläoklimatology,” Meteorologische Zeitschr., pp. 97–101, 1921 (with another figure).
- ↑ That is towards the equator.
