Detector WD 9 (Well) case

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Item Detector WD 9 (Well) case
Item code
Description 3 Element In crate
Donor Sun Oil
Location Houston Geoscience Center
Serial number
Taxonomy GSH149

Condenser-type seismometer, tills detector, contained an oscillating circuit wherein the spacing between two condenser plates varied with Seismic energy response, changing the output of an electronic tube in the Circuit. It may be part of the device referred to in the patent: "This application is a continuation of my co-pending application, Serial No.324,013, filed March 14, 1940, now abandoned." The virtue of this so-called condenser plate detector was that its response depended on the change in capacitance between two plates of a condenser which were connected in an oscillating current. The change in capacitance altered the average current in the vacuum tube oscillator which in turn made a proportionate electrical change in response to ground vibrations. This oscillating current was actually the invention of a Scotsman, Dowling, who had a patent. (Mr. Petty had obtained a license for geophysical purposes.) This geophone was so sensitive, relative to the standards of the time that it compensated to a large degree for the deficiencies in the early electronic vacuum tube amplifiers. The effective sensitivity was quite outstanding.