Earth Tides and Ocean Tides

Abstract

IN some respects notable progress has been made in the problem of the earth tides since 1862, when Lord Kelvin directed attention to the difference between the observed amplitudes of the fortnightly oceanic tides and their theoretical amplitudes on a perfectly rigid earth and based on this fact an estimate of the earth's modulus of rigidity. On the instrumental side, the interferometer apparatus of Michelson and Gale¹ represents a notable advance over the horizontal pendulum. On the theoretical side, the investigations of Herglotz, Schweydar, Love and Hoskins² have enabled us to deal with an earth which, so far as the physical properties of its interior are concerned, resembles the actual earth much more closely than does the homogeneous, incompressible sphere with uniform rigidity throughout treated by Lord Kelvin.