Topographic surveying; including geographic, exploratory, and military mapping, with hints on camping, emergency surgery, and photography . mwest bank, ; mean, ; extreme difference ofelevation, Turning-point 571 -f- 3670: from east bank, ; fromwest bank, ; mean, ; extreme difference ofelevation, The divergence of the lines for this days work was: at theeast bank, ft. ; at the west bank, ft. 156. Hand-levels.—A very useful little instrument forthe topographer is the hand-level, by which approximate level 356 LEVELING OF PRECISION. li
Topographic surveying; including geographic, exploratory, and military mapping, with hints on camping, emergency surgery, and photography . mwest bank, ; mean, ; extreme difference ofelevation, Turning-point 571 -f- 3670: from east bank, ; fromwest bank, ; mean, ; extreme difference ofelevation, The divergence of the lines for this days work was: at theeast bank, ft. ; at the west bank, ft. 156. Hand-levels.—A very useful little instrument forthe topographer is the hand-level, by which approximate level 356 LEVELING OF PRECISION. lines can be determined for some distance from the positionof the observer and thus aid him in following the course oflevel or contour lines. This instrument consists of a brasstube six inches in length with a small level on top near theobject end. (Fig. III.) Beneath is an opening through whichthe bubble can be seen as reflected from a prism into the eyeat one end. Both ends are covered by plain glass, while thereis a small semi-convex lens in the eye end to magnify the level-bubble and the cross-wires beneath the bubble. The cross-. FiG. III.—Locke Hand-level. wires are fastened to a small frame moving under the bubble-tube, and are adjusted in place by a small screw at the end ofthe bubble-case. By standing erect and sighting any objectand lowering or raising the object end of the level by handuntil the reflection of the bubble is exactly bisected by thecross-wires, a horizontal line will then be sighted and the po-sition of the horizontal cross-wire will indicate approximatelythe elevation of any object which is at the same height as theeye of the observer. 157. Using the Locke Hand-level.—There are two waysof leveling zuitli the Locke hand-level. One is for the ob-server to stand erect, measure the height of his eye againsta pole and note this height—say five feet. Then he directsthe hand-level at the side of a hill or of a tree-trunk andnotes where the horizontal wi
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