Usual methods of tidal analysis, developed by Darwin, Doodson, Lecolazet, Pertzev, Lennon and others, have been used for analyzing earth tidal data. With the recent remarkable progress of electronic computers, the least square method and Fourier analysis are also used widely for the same purpose. In the present article, results of the analysis of earth tidal data by means of the least square method are presented. The data were obtained with an Askania gravimeter No. 111 at Kyoto. The results thus obtained were in good agreement with those by the usual methods. A program for the least square method was written with the FORTRAN II and it is available for analyzing not only the earth tidal data but also for any periodic phenomena.

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Gravimetric and tiltmetric records of one year duration, observed at Kyoto and Akibasan (Wakayama), respectively, have been analyzed by the Fourier transform method, to get the spectral structure of the earth tides and related phenomena. The obtained spectral features are in excellent agreement with those predicted from tidal theory. The amplitude and phase for 8 principal constituents of diurnal and semidiurnal tides are determined for their proper periods, and compared with those by the method of least squares. The comparison between them shows satisfactory agreement. Some spectral peaks with periods of 11.1, 11.9, 16.2, 18.5 days and others, as well as for the fortnightly constituents Mf (13.66 days) and MSf (14.77 days), are also found in longer period ranges.

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Polar orbit has usually been represented by a smoothed curve, but a considerably large irregularity which seems to be beyond the smoothing is sometimes found in polar motion suggesting an abrupt change of its tendency. The corelation between abnormal change in the polar motion and that in tidal variation of gravity is investigated in the present article, showing considerably close relation. Origins of the abnormal change in the polar motion are not yet precisely known.

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[in Japanese]

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As a preliminary step to set up the Japan gravity standardization line, two series of observations were carried out under the cooperation of the U. S. Army Map Service Far East and the Geographical Survey Institute by using La Coste and Romberg geodetic gravity meters which had been calibrated along the North American calibration line. The established standardization line consists of 21 stations distributing from Wakkanai, northern Hokkaido, to Kagoshima, southern Kyushu, via Tokyo and Kyoto and has the gravity range of 1175 mgals. The first series of observations was made in May, 1963, with one gravity meter, G-4, whereas four meters, G-19, G-24, G-55, and G-69, were used for the second series in July, 1964. The instruments were transported mostly by air and partly by train. Combining the results of the both series of observations, gravity values at these stations were determined based on that at G. S. I., Tokyo, 979.7770. These values are the most accurate ones at the present time and can be used for calibrating gravity meters as well as for standardizing the gravimetric network in Japan until final values are obtained from simultaneous adjustment of pendulum and gravity meter data. Observations with a similar gravity meter, La Coste and Romberg G-29, which belongs to the Geographical Survey Institute and has been used for domestic survey were made at the same time and a correction factor, +56/100, 000, applicable to the calibration table given by the maker was obtained.

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