Hasluck, Paul N. (Paul Nooncree), 1854-1931 · London ; New York : Cassell and Co. · leaf 46
detect the true relative position of the three white spots, as the eye is easily deceived. In the drawing the white dots are uniformly spaced, but, to most people, the distance on the right- hand space looks much longer than that on the left, solely by reason of the lines drawn angleways confusing… … Fig. 67.—Two Parallel Straight Lines Appear Curved. centre. This same principle is shown more strikingly in Fig. 68, where the vertical lines are all truly parallel, although they look to be alternately converging and diverging. In Fig. 69 a true square is first drawn, and when part of the lower…
Mechanical drawing
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
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