Abstract
In the TEM tiltmeter [1] [2] [3], variation of tilt is mechanically amplified with a cross suspended pendulum whose deflection is transformed to electric signal through a differential transformer. In this instrument, a small effect due to variation of the geomagnetic field still; remained in spite of magnetic shield of the transformer. This was eliminated by using a case of steel of high permeability. Small inclination of the mounting table is given by a micrometer screw incorporated with a lever and two parallel plate spring system as a reduction mechanism. In the oldtype instrument, the turn values of the micrometer head were calculated from the dimensions of the reduction mechanism. It is found, however, that these calculated values are somewhat different from the experimental values measured with a precise dial-gauge (several per cent). It is ascertained that the drift rate may become smaller than 1×10-6(0"2) per year. The author also analysed the both data obtained with VM and TEM tiltmeters installed in the Akagane Station (Mizusawa) by the method of least squares.
