Lehner-Griffith Long Period Galvanometer

Description

This galvanometer was one of the first to be able to record seismic waves of long periods. It led to a number discoveries soon after its invention, during the International Geophysical Year (1957-1958). Through the widespread use of long period seismograph systems – the name given to seismographs equipped with long period galvanometers – during the International Geophysical Year, geophysicists were able to understand the dispersion and velocities of seismic waves at the surface, and, hence, were able to estimate the structure and thickness of the Earth’s crust for the first time.