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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