A treatise on surveying, comprising the theory and the practice (1906)
Gillespie, William Mitchell, 1816-1868, Staley, Cady, 1840- · New York D. Appleton · leaf 361
the darker it will appear. Horizontal surfacesare made white. Thegradation of shade forvarying slopes is deter-mined by rules whichgreatly exaggerate thedifferences in shade,since in the methodsemployed the intensityvaries directly with the angle from white at 0 to black at from 45to 75°, depending… … ^^^^^iiiiiiiiiliii^ THE HORIZONTAL SYSTEM. 351 corner of the map, making an angle of 45° with the vertical, willbe lightest, while the side most remote from the light will appeardarkest. The gradation in shade now used in this method, asdiffering from that due to vertical illumination, may be…
Surveying
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