THE EEASON WHY. 113 



Evening, and morning, and at noon, will I pray, and cry aloud ; and he shall 

 hear my voice." PSALM IT. 



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 wore 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 tlie 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 

 ure bent out of their course. 



479. Why is the apparent depth of water always decep- 

 tive ? 



Because the light reflected from the objects at the bottom is 

 refracted as it leaves the water. 



480. How much deeper is water than it appears to le ? 



About one-third. A person bathing, and being unable to swim, 

 should calculate before jumping into the water, that if it looks two 

 feet deep, it is quite three feet. 



481. Why can we seldom at the first attempt touch 

 anything lying at the bottom of the water with a stick? 



Because we do not allow for the different refractive powers of 

 water and of air 



