Worthen, William Ezra, 1819-1897, [from old catalog] ed · New York, Appleton · leaf 115
Fig. 226. … TOPOGRAPHICAL DRAWING. 99 In describing ground with the pen, the light is generally supposed todescend in vertical rays, and the illumination received by each slope is di-minished in proportion to its divergence from the plane of the horizon. Thus,in Fig. 228, it will be seen that a horizontal…
Mechanical drawing
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