Each of the 120 stations in the World Wide Standard Seismological Network had three short-period galvanometer control units for use with its three short-period galvanometers (such as 1999.0275.08). This example is marked “Galvanometer Control / Geotechnical Corp. / Dallas, Texas / Model 8438 / Serial 357.” It was used at Georgetown University in Washington, D.C.
Established in the early 1960s, the WWSSN was a key component of VELA Uniform, a Cold War project that was funded by the Advanced Research Projects Agency (ARPA), a branch of the Department of Defense. The WWSSN was designed to detect underground nuclear tests and generate valuable information about the earth’s interior and its dynamic processes. It was managed by the U.S. Coast and Geodetic Survey and then by the U.S. Geological Survey. That agency transferred this instrument to the Smithsonian in 1999.
Incorporated in 1936, the Geotechnical Corporation conducted research in and produced instruments for the earth sciences. It got into defense work after World War II, went public in 1962, and was bought by Teledyne in 1965.
Ref: United States Coast and Geodetic Survey, Instrumentation of the World-Wide Seismograph System, Model 10700 (Washington, D.C., 1962).