Perspective, a series of elementary lectures (1899)
Cone, Ada · New York, W.T. Comstock · leaf 56
50 PERSPECTIVE. an ellipse may be any width between a straight line and a circle, these two being the perspective poles of the curve. … There needs yet a little further construction, for ij is necessary to fix not only the outside limit for the petals, but also the point from which they start, E. When the outline appears a circle this point is, of course, the center of the circle, as shown at Fig. 22, and when the view is a side…
Perspective · Drawing
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
![An illustration from Nicolai Copernici Torinensis De reuolutionibus orbium coelestium, libri VI : Habes in hoc opere iam recens nato, & aedito, studiose lector, motus stellarum, tam fixarum, quàm erraticarum, cum ex ueteribus, tum etiam ex recentibus obseruationibus restitutos: & nouis insuper ac admirabilibus hypothesibus ornatos. Habes etiam tabulas expeditissimas, ex quibus eosdem ad quoduis tempus quàm facillime caculare poteris. Igitur eme, lege, fruere. [Line in Greek] (1543)](https://img.insideoutlibrary.com/img/200/ia-nicolaicopernici00cope-259-164.webp)
