| 摘要 |
In electromagnetic instruments that continuously transmit and receive low-frequency fields in order to sound the earth, it is known to change the orie ntations of the transmitter and receiver to alter the depth of sounding. In this invention, a novel arrangement of one transmitter and two receivers enables simultaneous sounding o f the earth to two distinct depths. The transmitter and receivers may be secured to an arcuate boom which, at the same time, allows a single operator to carry the inst rument conveniently across the earth to be sounded, and positions the transmitter and r eceivers near the earth to increase the depths of sounding.
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