In [Fig. 19] the circle nearer the apex of the angle appears larger than the other. This has been presented as one reason why the sun and moon appear larger at the horizon than when at higher altitudes. This explanation must be based upon the assumption that we interpret the “vault” of the sky to meet at the horizon in a manner somewhat similar to the angle but it is difficult to imagine such an angle made by the vault of the sky and the earth’s horizon. If there were one in reality, it would not be seen in profile.
Fig. 19.—Circles influenced by position within an angle.
Fig. 20.—Contrasting angles.
If two angles of equal size are bounded by small and large angles respectively, the apex in each case being common to the inner and two bounding angles, the effect of contrast is very apparent, as seen in [Fig. 20]. In [Fig. 57] are found examples of effects of lines contrasted as to length.
