. Elementary physical geography . fective as the hachure method, it is 437 438 PHYSICAL GEOGRAPHY. superior to this in many respects. A contour is a line of equal is the line to which the sea would rise if the land were depressed tothe depth represented by the height of the line. If we imagine our-selves near the seashore, the coast line is then the contour line of 0,and the 100-foot contour line is that to which the sea would reach if itwere raised just 100 feet. The contour map (Figs. 150, 190, 228, and Plate 25) is made upona horizontal scale which varies in different cases. In
. Elementary physical geography . fective as the hachure method, it is 437 438 PHYSICAL GEOGRAPHY. superior to this in many respects. A contour is a line of equal is the line to which the sea would rise if the land were depressed tothe depth represented by the height of the line. If we imagine our-selves near the seashore, the coast line is then the contour line of 0,and the 100-foot contour line is that to which the sea would reach if itwere raised just 100 feet. The contour map (Figs. 150, 190, 228, and Plate 25) is made upona horizontal scale which varies in different cases. In this country theusual scale is one inch to the mile: that is, every mile of country isallowed one inch. No allowance is made for the vertical element ofthe country. Thus if a region of considerable irregularity is beingmapped, an inch on the sheet is made to represent one mile in a hori-zontal direction. As one stands upon the side of a hill, and looks acrossa valley to another hillside at the same elevation, and a mile distant,. Fig. 267. the horizontal line is just one mile in length; but if the observer shouldstart to walk from the place where he stood, to the point to which helooked, he would need to travel considerably more than a mile. Onordinary maps this greater distance is not shown; but on the contourmaps it is brought out by means of the contour lines. The inch repre-sents the horizontal mile. Each descent or ascent finds a representationin the contour lines; and if they are close together, one sees that thevertical distance to be traveled is very great. There is much difference in the scale of elevation represented by con-tour lines. On most of the maps in the eastern part of the United States,every 20 feet of ascent or descent is represented by a contour line, andwe speak of this as the contour interval. Let us suppose ourselves pass-ing over an irregular country. Imagine that we are to travel a dis- APPENDIX II. 439 tance of one mile, in the course of which we go
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