New instrument - a vertical seismometer with magnetic suspension

Abstract

Vertical seismometers are based on pendulum systems made of a mass hanging from metallic springs of different types to eliminate the disymmetry of oscillatory movement. At time some sort of elastic circular diaphragm is added to fuuction as a transductor, occasionally reduced to three elastic plates or threads in the Benioff type seismometers. Through a mathematical analysis of spring seismometers it has been found that if the spring constant is large, the system functions as an accelerograph, while if the constant is small the sytem may be used to measoure displacements. After some practical considerations of the construction of·vertical seismometers and of propertie of metallic spring, a mathematical treatment of their handling and applications is given. In order to obtain an accurate interpretation of seismograms, some corrections accounting for variations of the magnetic field should be introduced as described in the text.