6 ANIMAL LIFE UNDER WATER 



seen the compressed head and shoulders and the 

 distorted features of the angler who appears to 

 be looking down upon the observer over the 

 edge. 



The point z 1 on the arc of the circle in the 

 lower illustration corresponds to the point z in 

 the upper part, and the reflecting surface z 1 to 

 w 1 to the surface between z and w. 



A subaquatic view differs from terrestrial 

 scene in that the foreground is always well 

 lighted — provided the scene is not too deep under 

 the water — while outside the range of this light 

 the bed of the pond or river appears darker and 

 darker, until the reality and the reflection blend 

 in the gloomy distance. 



A perfect reflection from the surface of the 

 water is only obtained when that surface is un- 

 broken. The appearance of objects, as seen 

 from below, when the surface of the water is 

 disturbed will be referred to later. 



The size of the " window " varies with the 

 position of the observer ; roughly, the radius of 

 the circle corresponds to the depth of the point 

 of observation, below the surface. With the 

 eye three feet below the water the circumference 

 of the hole would be approximately eighteen 



