Lange, David C. (David Christoph) · New York : John Wiley & Sons ; London : Chapman & Hall · leaf 67
ichlight is excluded. The Umbra of a point is a line. TheUmbra of a straight line is a straight line or a plane; whilethe Umbra of a plane is a plane or a sohd. (Fig. 9.) 18. Real Shades and Shadows are those which haveactual existence. Imaginary Shades and Shadows are thosewhich have no real… … Invisible shadeInvisible shade line GENERAL PRINCIPLES 57 existence but cannot be seen in projection, and which aretherefore dotted in on a drawing. (Figs. 9 and 13.) 19. The Shadow of any object is found by passingRays of Light through the object, and determining wherethe Rays intersecting the…
Shades and shadows · Geometry, Descriptive
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