Fig. 15.—SHOWING THE LINES OF INCIDENCE AND REFLECTION OF THE SUN'S RAYS AT NOON AND AT EVENING.

It is obvious from the foregoing diagram that the evening rays of reflection fall upon the eyes of spectators, while the reflections at noon are so perpendicular that they are lost.

525. Why do the sun and moon appear smaller when near the meridian, than when near the horizon?

Because, when near the horizon, they are brought into comparison with the sizes of terrestrial objects; but when near the meridian they occupy the centre of a vast field of sky, and as there are no objects of comparison surrounding them, they appear smaller.

This is one "Reason Why," assigned by some observers. But there is also another reason to be found in the fact that, when the sun or moon is near the horizon, we view it through a greater depth of atmosphere than we do when at the meridian. (See [Fig. 13].) A straight line passed upward through the air, would not be so long as that which passes to S. Consequently, as the air is generally impregnated with moisture, at the time when these effects are observed, the rays of light are caused to diverge more, and the disc of the sun or moon appears magnified. Probably both of these reasons contribute to the effect. This latter reason also explains why the disc of the sun or moon may sometimes appear oval in shape, the lower stratum of air being more loaded with moisture than that through which we view the upper part of the disc.

"There is no darkness nor shadow of death, where the workers of iniquity may hide themselves."—Job xxxiv.

526. Why do our shadows lengthen as the sun goes down?

Because light travels only in straight lines, and as the sun descends, the direction of his rays becomes more oblique, thereby causing longer shadows.