Davies, Charles, 1798-1876 · New York, Cincinnati [etc.] American book company · leaf 369
n the surface. If the slope rod isused, the sum of the vertical measurements or readings will bethe vertical distance of (7 above A. Should the tunnel at B behigher or lower than at A, the difference subtracted from oradded to the sum of the vertical readings, will be the requireddepth of the… … Fig. 189. Determine the depth of the shaft BF, by suspending a chainfrom the surface or by a steel tape with a weight attached.Measure the length of the tunnel FH^ already completed, and,with the slope rod, or otherwise, obtain the horizontal distanceDI, and the difference of level between the…
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