The well known “Richter Scale” is tied to this particular seismometer. It was replaced with the Moment Magnitude Scale, a measure of energy released in an earthquake.
Schematic drawing of the Wood-Anderson torsion seismometer, 1948, 10.50-14. Caltech Images Collection, Images. California Institute of Technology Archives and Special Collections. https://collections.archives.caltech.edu/repositories/2/archival_objects/111814 Accessed February 02, 2024.