A modified wild‐pattern earth‐inductor inclinometer
William E. Wiles · Transactions American Geophysical Union · 1948
In the spring of 1940, the Division of Geomagnetism and Seismology of the United Estates Coast and Geodetic Survey undertook the planning of a now type of observatory earth inductor. Most of the planning and general supervision of the work was accomplished by Fred Keller, Jr., of the Division, the major part of tho drafting being done by A. K. Howerter of the Division of Charts. All of the construction work was done by the United States Naval Observatory. Two new earth inductors were built, No. 7 and No. 8. After preliminary tests and observations indicated the acceptability of the instruments, it was decided to ship No. 7 to the San Juan Magnetic Observatory, to serve as the permanent, absolute instrument of the Observatory, replacing the one in use, and to retain No, 8 for use as a model in the construction of additional earth inductors. The eventual plan was to replace the old earth inductors in use at all of the observatories of the Bureau with the new, modified, improved type.