A treatise on surveying ; in which the theory and practice are fully explained (1860)
Alsop, Samuel · Philadelphia, E. C. & J. Biddle & co. · leaf 311
cal, let fall a plumb-line from thesummit, and describe, the circles around the point in whichthis line cuts the surface. A piece of tin, with a small cir-cular hole through it for the suns rays to pass through, isbetter than the top of the staff, the image being definite. Where much accuracy is… … Sec. L] MERIDIANS. 309 Those days—or at least a time not very remote from them—should therefore be chosen for determining the meridianby this method. 413. Second Method. — By a meridian observation of theNorth Star. Tlie Pole Star {Polaris, or a Ursce Minoris) is situatedvery nearly at the North…
Surveying
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