. Deep borehole surveys and problems. Boring. 104 DEEP BOREHOLE SURVEYS AND PROBLEMS tion of the inclination and azimuth at which it set while, say, 500 ft. deep in the borehole. It is easy therefore, after its withdrawal, to tilt it to the same angle and to the same quarter of the compass as before by simply bringing the embedded plummet to the vertical, and the needle to the meridian. These clinostats are heated, inclosed within their brass protecting tubes and lowered by rods on a line to the desired spot in the borehole. Their contents are allowed. Fig. 53.—MacGeorge's clinometer. to cool
. Deep borehole surveys and problems. Boring. 104 DEEP BOREHOLE SURVEYS AND PROBLEMS tion of the inclination and azimuth at which it set while, say, 500 ft. deep in the borehole. It is easy therefore, after its withdrawal, to tilt it to the same angle and to the same quarter of the compass as before by simply bringing the embedded plummet to the vertical, and the needle to the meridian. These clinostats are heated, inclosed within their brass protecting tubes and lowered by rods on a line to the desired spot in the borehole. Their contents are allowed. Fig. 53.—MacGeorge's clinometer. to cool and congeal and are then withdrawn for inspection. The phial with its congealed contents is placed in a sheath of brass tubing (Fig. 53) attached to a movable arm which carries the index of a vertical arc. This sheath corresponds with the Y's of a theodolite, and carries the phial firmly upon the same principle as these carry the usual telescope. The upper bulb of the phial is brought into the field of two crossed microscopes, which are carried with the arm round the vertical arc; these are kept truly in the same plane at every angle of inclination by a parallel motion. There are vertical lines drawn upon the object glass of each micro- scope, these being, of course, kept truly vertical by the. 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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