. Deep borehole surveys and problems. Boring. 192 DEEP BOREHOLE SURVEYS AND PROBLEMS as a whole, and in such cases mechanical means must be used. The Mechanical Guide of the Rods.—The above-mentioned rods of stiff members with cross links are movable on all sides in their long axis but not at all in the cross direction, so that they can follow a winding hole without losing their orientation. Thus the borehole course is resolved into short pieces. The correct working of these guides is an important preliminary of all surveys. Trial of rods through 180 deg. before every test is considered a good
. Deep borehole surveys and problems. Boring. 192 DEEP BOREHOLE SURVEYS AND PROBLEMS as a whole, and in such cases mechanical means must be used. The Mechanical Guide of the Rods.—The above-mentioned rods of stiff members with cross links are movable on all sides in their long axis but not at all in the cross direction, so that they can follow a winding hole without losing their orientation. Thus the borehole course is resolved into short pieces. The correct working of these guides is an important preliminary of all surveys. Trial of rods through 180 deg. before every test is considered a good Fig. 132.—Borehole survey by Haussmann's method. In plumbing a hole in undisturbed conditions, first arrange marks for depth measurements on the rope or use a measuring wheel, or, if using rods, mark the rods for a given direction on the scale of the registering apparatus. Now when ready switch in the resistance for the lamp and solenoid and read with the ammeter and voltmeter. The first survey is made with the plumb cyUnder hanging free in the hole. By means of the switch lever we can. 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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