ICANUAL rOR NONCOMKISSIONEB OFFIC£ES. 321 



"Which way does this stream run?" 



Water flows down hill. If you are in the bed of a stream, 

 contours representing higher ground must be to your right 

 and to your left. Get the elevations of these contours. Gen- 

 erally the nearest contour to the bank of the stream will cross 

 the stream, and there will be an angle or sharp turn in the 

 contour at this crossing. If the point of the angle or sharp 

 turn is toward you, you are going downstream ; if away from 

 you, you are going upstream. 



If the contours are numbered, you have only to look at the 

 numbers to say where the low and where the high places are ; 

 but to read a map with any speed one must be quite independ- 

 ent of these numbers. In ordinary map reading look, first of 

 all, for the stream lines. The streams are the skeleton upon 

 which the whole map is hung. Then pick out the hilltops and 

 ridges, and you have a body to clothe with all the details that 

 will be revealed by a close and careful study of what the map 

 maker has recorded. 



As to closed contours, they may outline a depression or a 

 hill. On the map " 881 " or " 885 " might be hills or ponds, as 

 far as their shape is concerned. But, clearly, they are hills, 

 for on either side are small streams running aicay from them. 

 If they were ponds, the stream lines would run toward the 

 closed contours. The test of " hill, valley, hill," will always 

 solve the problem when there are not enough stream lines 

 shown to make evident at once whether a closed contour 

 marks a pond or a hill. Look in the beginning for the stream 

 lines and valleys, and, by contrast, if for no other reason, the 

 hills and ridges at once loom up. 



To illustrate the subject of contours to aid those who have 

 difficulty in reading contoured maps the following is sug- 

 gested : 



1. Secure modeling clay and build a mound. 



2. Use wire and slice this mound horizontally at equal ver- 

 tical intervals into zones ; then insert vertical dov/els through 

 the mound of clay. 



3. Remove the top zone, place on paper, and draw outline of 

 the bottom edge. Trim your paper roughly to the outline 

 drawn. Indicate where the holes made by the dowels pierce 

 the paper. 



366°— 17 12 



