. Deep borehole surveys and problems. Boring. 28 DEEP BOREHOLE SURVEYS AND PROBLEMS The results obtained are very satisfactory but the apparatus exhibits the same deficiencies as Lapp's appa- ratus because the basis of the record is time and not the revolutions of the rods, and here even in a higher degree. Since the motion of the recording surface is always uniform it turns too quickly in solid strata and too slowly in broken strata. In this way the variations in the recorded line, upon which the stratigraph depends as stated previously, are weakened, while in Lapp's method where the pen work
. Deep borehole surveys and problems. Boring. 28 DEEP BOREHOLE SURVEYS AND PROBLEMS The results obtained are very satisfactory but the apparatus exhibits the same deficiencies as Lapp's appa- ratus because the basis of the record is time and not the revolutions of the rods, and here even in a higher degree. Since the motion of the recording surface is always uniform it turns too quickly in solid strata and too slowly in broken strata. In this way the variations in the recorded line, upon which the stratigraph depends as stated previously, are weakened, while in Lapp's method where the pen works by clockwork they are increased. The irregularities in the velocity of rotation of the rods in working are of no great importance since the expenditure of power for the proper action of the crown is small as compared with the movement of the rods. Depth Measurers.—There are many types of these, the simplest being the direct types. Figure 7 shows the simple . Measuring ^ Wheel. Frame Rone K>i Fig. 7.—Depth measurer. direct depth measurer of the Lucey Products Corporation of Tulsa, Oklahoma, known as the Thatcher Depth- ometer. It is easily assembled on a rod frame and is very portable, being only 15 to 16 lb. in weight and can be used on ropes up to Ij.^ in. diameter. The measuring wheel transmits its revolutions by toothed gearing for direct reading, and it can be used on bailing and apparatus lower- ing ropes as well; also it can be used when letting the rope into the hole or when pulling it out. Borehole Diameter Measurers.—Decisions as to the variations in the diameter of a borehole are often necessary to settle difficulties arising during 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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