ON THE OBSERVATIONS OF THE TIDAL STRAINS AT OSAKAYAMA OBSERVATORY

Abstract

The studies on the observations of the earth's tidal strains and tiltings have been performed with extensometers, a recording water-tube tiltmeter and rotationmeter chiefly at Osakayama Observatory and partly at Kishu Mine and Suhara Observatory. The tidal number hz and lz, the quantities relating to their radial gradients are evaluated by analyses of the observing tidal extensions. The tidal constants of the ground tilting are obtained from the observation with the water-tube tiltmeter and are compared to those of the pedulum type's tiltmeters obtained by E. Nishimura. Recently, we have devised a rotationmeter to observe directly the tidal rotations and the horizontal shear strain, and has been carried out to observation at Osakayama Observatory. According to the observations, the result obtained with the rotationmeter seems to have approximate agreement with those obtained with extensometers.