. Deep borehole surveys and problems. Boring. Fig. 86.—Equipotential lines in receiv- ing-dish. First Fig. 85.—Clinophone wiring diagram. Fig. 87.—Equipotential lines in receiv- ing-dish. Third arrangement. hearing is found by short-circuiting the electrodes in adja- cent pairs and coupling an earphone between the pair using the good ear only. Such an arrangement (Fig. 87) will give a locus of minimum noise points as a straight line. Short-circuiting on another cardinal point electrode we get another minimum noise line. The intersection of these two loci can be easily and exactly
. Deep borehole surveys and problems. Boring. Fig. 86.—Equipotential lines in receiv- ing-dish. First Fig. 85.—Clinophone wiring diagram. Fig. 87.—Equipotential lines in receiv- ing-dish. Third arrangement. hearing is found by short-circuiting the electrodes in adja- cent pairs and coupling an earphone between the pair using the good ear only. Such an arrangement (Fig. 87) will give a locus of minimum noise points as a straight line. Short-circuiting on another cardinal point electrode we get another minimum noise line. The intersection of these two loci can be easily and exactly fixed and is the point sought; now read off its dip and bearing in the dish scale. The average reading error of an observation is about 5 min. of arc with an 18i^-in. plumb bob, and this may be reduced by carrying a longer plumb line or by having a check reader and alternative Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Haddock, M. H. (Marshall Henry). New York, McGraw-Hill
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