This site is devoted to the reporting, study, and development of seismic sensors. I have been interested in seismology and earthquakes for many years. In December 1998 I attended a meeting of the Northern California PSN at the Menlo Park office of the USGS. Several members brought in their homemade seismometers to show and explain how they worked. It took another 10 years to get my first Lehman seismometer up and running. This was the start and next came the Force Balance Vertical seismometer.