[Footnote 11: ] For by the construction A T ∶
a
T ∷ B T ∶
b
T;[eqn ii] and therefore the two triangles A B T,
a b
T, (having a common angle A T B,) are similar.] [Return to text]
[Footnote 12: ] The demonstration is in [Appendix II. Article I].] [Return to text]
[Footnote 13: ] The reflection in water of any luminous point or isolated object (such as the sun or moon) is therefore, in perspective, a vertical line; since such reflection, if produced, would pass under the feet of the spectator. Many artists (Claude among the rest) knowing something of optics, but nothing of perspective, have been led occasionally to draw such reflections towards a point at the center of the base of the picture.] [Return to text]