A treatise on surveying, comprising the theory and the practice (1906)
Gillespie, William Mitchell, 1816-1868, Staley, Cady, 1840- · New York D. Appleton · leaf 364
5°, the first being white and the last black (Fig.521). For the intermediate slopes he makes the white to the blackin the following proportion : The white : the black : : 45° — angle of slope : angle of slope. For example, for 30° : Light : shade : : 45° - 30° : 30° : : 1 : 2. THE VERTICAL SYSTEM.… … breadth than those for the 40° slope, but showing the same widthof white between them. Fig. 522 is a hill drawn by Lehmanns method. Also, to distinguish slopes varying from 0° to 5°, an exception Fig. 521. f !■ 10° 20° 25 30
Surveying
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