International Correspondence Schools · Scranton, Pa. : The Colliery engineer co. · leaf 75
ations, a hand level, which fits closely to theangle of the rod and carries two small spirit levels, is used toaccurately plumb it. In using a rod which is not self reading,all readings are taken with the target. 1279. Examples in Direct Leveling.—The princi-ples of direct leveling are illustrated… … 8.42 feet, called a backsight,is the distance which the pointwhere the line of collimation cutsthe rod is above the point A, andis to be added to the elevation ofLhe point A. 20.00 + 8.42 = 28.42is called the height of instrumentand designated H. I. The instru-ment being turned in the…
Railroad engineering
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