The amateur's perspective : being an attempt to present the theory in the simplest form; and so to methodize and arrange the subject, as to render the practice familiarly intelligible to the uninitiated in a few hours of study (1828)
Davenport, Richard, author · London : Printed for the author · leaf 30
he card from that point, nearly down to one part of the base. As at fig. 1 in following diagram. Cut the other card down to an obtuse-angled triangle, as at e b d , fig 2. Set the first card on its base, and put the triangle through the slit, so that the angle e be brought up to the supposed eye of… … It follows that the perspective of the line b d running perpendicularly to the base, is in the oblique line of fig. 1, (the slit in the card,) and if the ground line b d be extended to the horizon (or in other words, if a visual ray in that perpendicular proceeds from a point in the horizon), the…
Perspective
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
