. Early geophysical papers of the Society of Exploration Geophysicists . - , Fig. 1.—Refraction fan layout for exploration of Vermilion Bay. In the survey of Vermilion Bay, three recording boats were used. Each was equipped with a radio transmitter and receiver, an oscillo- graph, and a velocity meter (geophone) recording through a vacuum tube amplifier. The timing device was an electrically operated 50- cycle tuning fork. The air wave was picked up by a carbon-button unit'. The resulting records were developed immediately, thus guiding the observers in the size of the next shot. The instant o
. Early geophysical papers of the Society of Exploration Geophysicists . - , Fig. 1.—Refraction fan layout for exploration of Vermilion Bay. In the survey of Vermilion Bay, three recording boats were used. Each was equipped with a radio transmitter and receiver, an oscillo- graph, and a velocity meter (geophone) recording through a vacuum tube amplifier. The timing device was an electrically operated 50- cycle tuning fork. The air wave was picked up by a carbon-button unit'. The resulting records were developed immediately, thus guiding the observers in the size of the next shot. The instant of explosion was determined by the breaking of a wire wrapped around part of the charge of explosive, thus terminating the operation of the shot trans- mitter. In general, the charge of explosive was simply lowered to the 383
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Keywords: ., bo, bookcentury1900, booksubjectpetroleum, booksubjectprospecting
