The elements of art; a manual for the amateur, and basis of study for the professional artist (1848)
Chapman, J. G. (John Gadsby), 1808-1889, Chapman, J. G. (John Gadsby), 1808-1889. American drawing book · London, D. Bogue · leaf 54
RUDIMENTS OF DRAWING. 50 … through these points ceases, necessarily, to be a straight line, and according to the degree of elevation or depression of the head, is its degree of variation and curvature. It is still, however, the governing line for the true position of the features, which must harmonize and agree with it upon…
Drawing
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.