A treatise on surveying, comprising the theory and the practice (1906)
Gillespie, William Mitchell, 1816-1868, Staley, Cady, 1840- · New York D. Appleton · leaf 51
gulation, where it is desirable to completethe observations at a station as soon as possible. Even then, if thegraduation is good and the verniers read finely enough, it may bebetter to use the method of directions, keeping the lower movementclamped, excepting to shift the zero of the graduation… … CROSS HAIRS. 41 means for reading the circle accurately, usually the micrometermicroscope. Some device for shifting the zero-point of the graduation on thelimb, or graduated circle, must be used with all direction instru-ments. When the instrument rests upon a masonry pier a positioncircle must be…
Surveying
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