A manual for teaching model-drawing : from solid forms, the models founded on those of M. Dupuis : combined with a popular view of perspective, and adapted to the elementary instruction of classes in schools and public institutions (1843)
Williams, J. Butler, Sir, Lowry, Joseph Wilson, 1803-1879 · London : J. W. Parker · leaf 74
PRINCIPLES OF PERSPECTIVE. 53 to the size of the object, or the length of the line from which the rays proceed, increasing or diminish- ing according as the object is larger or smaller. In this example I diminish the visual angle one-half, if I shorten the line one-half. pc at right angles at b,… … equal lines cd,db. For, let the angle b a c be bisected by the line a e, meeting b c in e, then the segments c e, e b, shall have the ratio which the sides A c, A B, have to one another. (Eire. 3. VI.) But a c is greater than A b (Euc. 27- I.), therefore c E is greater than e b, but as c e and e b…
Drawing · Perspective
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
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