7.(Pg. [170]) What is the difference in sculpture, in this respect?
8.(Pg. [170]) Excepting the rays from an object enter the eye, under a certain angle, they cannot be seen; what must this angle exceed?
9.(Pg. [170]) What two circumstances may cause the angle to be so small, as not to produce vision?
10.(Pg. [170]) Motion may be so slow as to become imperceptible, what is said on this point?
11.(Pg. [170]) Under what circumstances may a body, moving with great rapidity, appear to be at rest?
12.(Pg. [170]) Upon what does the real velocity of a body, depend?
13.(Pg. [171]) What must be known, to enable us to ascertain the real space contained in a degree?
14.(Pg. [171]) What is explained by [fig. 2, plate 17]?
15.(Pg. [171]) What is said respecting the evidence afforded by our senses, and how do we correct the errors into which they would lead us?
16.(Pg. [171]) An image of a visible object is formed upon the retina of each eye, why, therefore, are not objects seen double?