Finch, James Kip, 1883- · New York : John Wiley & Sons, Inc. · leaf 90
ally all the visibleportions north of this hill are ridge lines. 3. The lower boundary of the visible area will run alongthe sloping hillside facing the observer. Its shape will depend AREA PROBLEM 69 on the form of the obstructing ridge nearer the observer,which prevents him from seeing to the… … Fig. 40.—Picture Plane. If the intervening hill is irregular in crest outline the boundaryline on the side of the hill in question will show similar irregu-larities that can be completely determined only by drawingmany radiating lines from the observers station. In choosing where to put the…
Cartography · Military maps
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