Quartz crystals were considered nothing more than a laboratory curiosity for almost 40 years after the discovery of piezoelectricity.
Walter Guyton Cady became interested in quartz crystals during World War I. Along with many other scientists at the time, Cady was involved in the effort to develop a way to detect enemy submarines by transmitting sound underwater. Although his work was not completed before the end of the war, it did lay the basis for the eventual development of sonar.
While professor of physics at Wesleyan University in Middletown, Connecticut, Cady developed the first quartz crystal resonator.
Cady discovered that a quartz crystal connected to a variable-frequency electronic oscillator would vibrate strongly at a very specific frequency, but that at other frequencies it would not vibrate at all. In this way, the quartz crystal resonator actually controlled the frequency of the oscillating circuit. Cady quickly realized that this circuit could be used as a frequency standard. In 1921 Cady and his colleagues at Wesleyan made the first quartz crystal resonator.
Born in Providence, Rhode Island, Cady (1874-1973) did both his undergraduate and master's work at Brown University. He received his Ph.D. from the University of Berlin in Germany in 1900, and was professor of physics at Wesleyan University from 1902 to 1946. He received many honors and awards during his lifetime and held more than 50 patents.
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