II. On periodic disturbance of level arising from the load of oceanic tides

• Published in: Philosophical Transactions of the Royal Society of London. Series A, Containing Papers of a Mathematical or Physical Character
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 1918
• Subjects: Tilting; North Atlantic
• Online Access: http://dx.doi.org/10.1098/rsta.1918.0002; https://royalsocietypublishing.org/doi/pdf/10.1098/rsta.1918.0002

In his important observations on the lunar deflection of gravity, Dr. O. Hecker has pointed out that the force acting on the pendulum at Potsdam is a larger fraction of the moon’s force when it acts towards the east or west than when it act towards the north or south. Various explanations of this anomaly have been proposed; among them one, suggested by Prof. A. E. H. Love, is that a possible cause may perhaps be found in the attraction of the tide wave in the North Atlantic. Recently Prof. A. A. Michelson has found a similar result in his arduous task, successfully achieved, of obtaining a continuous record of the lunar perturbation of a very long water-level at Chicago. Prof. Sir J. Larmor kindly suggested to me a query, whether the excess-pressure of the tide in the North Atlantic would affect much the measurement of water-level at Chicago, owing to the elastic depression of the earth’s surface that it would produce. In the present paper the calculation is undertaken in order to ascertain to what extent the consideration of tilting of the ground is important for the explanation of this geodynamical discrepancy, on the assumption that the earth consists of elastic matter of uniform density and of uniform invariable elastic constants, and that the North Atlantic may be represented roughly as a circular basin and that the tide in it is uniform or else elliptic. The curvature of the earth is neglected, which is, of course, admissible for a first estimation.