"Evening, and morning, and at noon, will I pray, and cry aloud; and he shall hear my voice."—Psalm lv.

Place in the bottom of an empty basin ([Fig. 11].) a shilling; then stand in such a position at the point B that the line of sight, over the edge of the basin, just excludes the shilling from view. Then request some one to pour water into the basin, until it is filled to C ([Fig. 12].), keeping your eye fixed upon the spot. The shilling will gradually appear, and will soon come entirely in view. Not only will the shilling be brought in view, but also portions of the basin before concealed. This is owing to the rays of light passing from the bottom through the water in a direction more perpendicular than they would have done through the air; but on leaving the water they become more oblique, and hence they convey the image of the shilling over the edge of the basin, which otherwise would have obstructed the view.

Fig. 12.

478. Why is it that in cloudy and showery days we see the sun's rays bursting through the clouds in different directions?

Because, in passing through clouds of different densities the rays are bent out of their course.