Periodic disturbance of level arising from the load of neighbouring oceanic tides
In Hecker’s observations on the lunar deflection of gravity, the force apparently acting on the pendulum at Potsdam is a larger fraction of the moon’s direct attraction when it acts towards east or west than when it acts towards north or south. A similar result has been found by Michelson in his obs...
| Published in: | Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character |
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| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
The Royal Society
1917
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1098/rspa.1917.0044 https://royalsocietypublishing.org/doi/pdf/10.1098/rspa.1917.0044 |
| Summary: | In Hecker’s observations on the lunar deflection of gravity, the force apparently acting on the pendulum at Potsdam is a larger fraction of the moon’s direct attraction when it acts towards east or west than when it acts towards north or south. A similar result has been found by Michelson in his observations of the lunar perturbation of water-level at Chicago. A calculation is here made to ascertain to what extent the tilting of the ground caused by the excess pressure of the tide in the North Atlantic is important for the explanation of this geodynamical discrepancy. Replacing the North Atlantic by a circular basin of radius 2000 kilom., taking the position of Chicago to be 1000 kilom. from the coast, and the rigidity of the earth to be 6 × 10 11 C. G. S., it is found that the attraction effect of a uniform tide per metre of height is about 0·0024", while its tilting effect is as much as 0·0069", the maximum of the direct lunar attraction being 0·017". If the surface of tide is ellipsoidal, shelving towards the coast, nearly the same result is reached for the same mean tidal height. |
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