ON THE M1-COMPONENT OBTAINED BY GRAVIMETRIC TIDAL OBSERVATION (SCREENING OF GRAVITATIONAL FORCES)

Abstract

Absorption of gravitational forces has mainly been investigated during periods of solar eclipse by several investigators, and it has been established that the absorption effect of gravitation, if it exists, does not exceed the noise level. The mass of the earth is larger than that of the moon and therefore the gravitational absorption due to the earth's mass itself should be larger than that due to the moon's mass. In the present paper, a trial to detect the absorption effect of the lunar gravitational forces by the earth's mass is described by using data obtained with an Askania gravimeter No. Ill, installed at Kyoto, during a period of one year. By the present investigation, it is ascertained that the gravitational absorption due to the earth's mass is about 4 ugal and that its value reaches a maximum two hours after the instant when the moon transited the meridian of the observation station. The value of amplitude obtained by observation is in good agreement with that predicted by theoretical calculation. But concerning the phase, there exists a difference of about 180° compared with that expected by theoretical calculation.