Later it became a practical alternative, for example with the Wood-Anderson torsion seismograph on which the Richter magnitude scale is based [Anderson & Wood 1925]. The electromagnetic seismograph with galvanometer-photopaper recording, invented by Galitzin already in 1904, remained for more than half a century the most sensitive long-period seismograph but had to wait for gradual improvements by LaCoste, Benioff, Press, Ewing, and Lehner