Topographic surveying; including geographic, exploratory, and military mapping, with hints on camping, emergency surgery, and photography . smatic compass (Arts. 64, 61, and 91) may be em-ployed, while heights may be determined with the aneroidor by vertical angulation (Arts. 160 and 174). For the rough determination of distance, four methodsmay be employed, viz.: 1. Measurement by odometer; 2. By counting the paces of a man or animal; 3. By use of the range-finder; or 4. By time estimates. Where distances are to be measured with greater accuracysome of the following methods may be used, viz.:
Topographic surveying; including geographic, exploratory, and military mapping, with hints on camping, emergency surgery, and photography . smatic compass (Arts. 64, 61, and 91) may be em-ployed, while heights may be determined with the aneroidor by vertical angulation (Arts. 160 and 174). For the rough determination of distance, four methodsmay be employed, viz.: 1. Measurement by odometer; 2. By counting the paces of a man or animal; 3. By use of the range-finder; or 4. By time estimates. Where distances are to be measured with greater accuracysome of the following methods may be used, viz.: 1. Tachymetric processes; 2. Chains or steel tape: or 3. Trigonometric processes. Where walking is necessary in order to get over theground, very satisfactory and economic measures of distancecan be had by pacing. With a little practice a degree ofaccuracy may be attained quite equal to that had in thedirection and elevation measurements with the crude instru-ments employed in reconnaissance work. It is desirable inpacing to adopt a stride shorter than the natural one; thus aman whose natural step in walking comfortably on level 224. PtATE IV—ISOGONIC CHA«tn to isogenic lines indicates west declination; tl»- sign indicates east declination. Annual change In declination gl«naltered figures preceded by + sign for increasing west or decrease cast declination; a - sign (or reverse motion. (Fr.™ V. S. Cost and Smw R-P » DISTANCES BY PACING AND TIME. 225 ground is a yard long should adopt in pacing a stride of 32inches; and a man whose natural stride is 30 inches shouldadopt a 28-inch pace. The best way to ascertain the lengthof stride is to measure off a distance of, say, 200 feet andpace this several times, finding how many paces are requiredto measure the distance. If 70 strides are taken in this dis-tance, for instance, the pacer should adopt a stride whichwill enable him to make the distance in 80 steps, and shouldpractice it with sufficient frequency to enable
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