Topographic surveying; including geographic, exploratory, and military mapping, with hints on camping, emergency surgery, and photography . h are continuous lines representing equal verticalintervals and which are in fact projected plans of the line atwhich a water surface (of the ocean, for instance) would inter-sect the surface of the earth were it raised successively by equalamounts. These contours are, then, curved lines which repre-sent in plan the country as it would appear if it were cut by aseries of equidistant horizontal planes. The contour interval,as it is called, or the distance b
Topographic surveying; including geographic, exploratory, and military mapping, with hints on camping, emergency surgery, and photography . h are continuous lines representing equal verticalintervals and which are in fact projected plans of the line atwhich a water surface (of the ocean, for instance) would inter-sect the surface of the earth were it raised successively by equalamounts. These contours are, then, curved lines which repre-sent in plan the country as it would appear if it were cut by aseries of equidistant horizontal planes. The contour interval,as it is called, or the distance between two contour lines, may beassumed at pleasure, but must be constant for the same map. Still another method of representing surface slopes is bycrayon or brush shading (Fig. 138), so as to give the effectproduced by hachures, bui in a uniform tint; and still anotherand perhaps the best method of all is that of shading acontour map in such manner as to produce the graphic reliefeffect resulting from hachures, while at the same time it retainsthe quantitative property given by contours. (Fig. 136.) METHODS OF MAP CONSTRUCTION. 451. Fig. 135.—Contour(Z>), Shade-line(^), and Hachure Construction(^). 452 TOPOGRAPHIC DRA WING, The representation of relief by Jiachnrcs is graphic this method quality of relief is the first consideration, andquantity or relative amount of relief is secondary. (Figs, 135and 143.) Where quantitative relief is necessary, as in thework of the engineer or geologist, a contour map is such a map is possessed of mathematical qualities andclearness that are lacking in the hachured map, it fails to alarge degree in representing the details of the surface, and,moreover, its representation of surface forms is difficult ofinterpretation by the inexpert. The representation of reliefby hachures has been characterized as a graphic system with aconventional element, and the contour method of representingrelief as a conventional system
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