On Continuous Observation of Gravity

Abstract

Change of gravity with time is generally divided into two branches. One is a periodic variation and the other non-periodic. The periodic variation of gravity is phenomena caused by the tide-generating forces due mainly to the sun and the moon and caused also by other origins with periodicities, and its variation is regular. The non-periodic change of gravity, if existing, is regarded to be related with rapid or gradual change of gravity caused by the change of state or motion of the ground material, the fluctuation of rotation speed of the earth, the crustal movement and the like. In the present paper, there are some comments about observations of the time change of gravity made by means of gravimeters. Method of calibration for the gravimeters and that of data treatment are also discussed briefly.