Davies, Charles, 1798-1876 · New York, Cincinnati [etc.] American book company · leaf 186
he angles of elevation at A and B. Hence, we can find all theparts of the triangle ABB. Having found BB, and knowingthe angle BBC, we can find the altitude BC. This method supposes that the stations A and B are on thesame horizontal plane; and therefore it can only be used whenthe line ^^ is nearly… … SEC. II.] MEASUREMENT OF ANGLES. 179 To determine the perpendicular distance of an object belowa given horizontal plane. 202. Suppose G to be directlyover the given object, and A thepoint through which the horizontalplane is supposed to pass. Measure a horizontal base-lineAB, and at the stations A…
Surveying
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