A treatise on surveying, comprising the theory and the practice ; (1887)
Gillespie, W. M. (William Mitchell), 1816-1868, Staley, Cady, 1840- [from old catalog] ed · New York, D. Appleton and company · leaf 179
. To determine the True Meridian. 262. By Equal Shadows of the Sun. On the south side of anylevel surface erect an uprightstaff, shown in horizontal pro-jection at S. Two or threehours before noon, mark theextremity, A, of its shadow.Describe an arc of a circlewith S, the foot of the staff,… … THE DECLINATION OF TEE MAGNETIC NEEDLE. 165 touches the arc at another point, B. Bisect the arc A B at N.Draw S 1ST, and it will be the true meridian, or north and southline required. For greater accuracy, describe several arcs beforehand, markthe points in which each of them is touched by the…
Surveying
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