224 THE REASON WHY: 



" With tvingy speed outstrip the eastern wind, 

 And leave the breezes of the mom behind." ADDISON. 



668. Why do eagles drive away their young? 



Because, as these birds subsist by prey, they would soon 

 produce a famine among their race did many of them dwell in 

 the same district. Therefore, the old birds drive away their 

 young at a certain age from their boundaries. 



669. Why are the wings of eagles broad, and hollow in their 

 under surfaces? 



Because the eagle, when in search of its prey, floats in the air 

 until its keen eye discovers that of which it is in quest ; by this 

 peculiarity of structure, therefore, the wings can take a more 

 powerful hold on the air, and the whole body is enabled to float 

 with little labour. 



670. Why are the wings of the eagle, though powerful, shorter 

 than those of the falcon, both being birds of prey ? 



Because falcons catch their prey while on the wing, and therefore 

 have the faculty of rapid and uninterrupted flight ; but the eagle 

 strikes its victim to the ground, or the waters, and afterwards rises 

 \vith it, thus requiring strengthin a greater degree than rapidity. 



671. Why, in the eye of the falcon, crane, and other birds of 

 pieioing sight, has the -flattened optie nerve one of its branches 

 folded ir*t/> numerous plaits ? 



By this arrangement, the extent of surface is considerably 

 augmented, and the powers of vision proportionally increased. 



672. Why are the eyes of birds and animals who seek their 

 prey by night, or in the dark, larger than those of other animals ? 



Because the large eye of the nocturnal animal admitting more 

 light, and taking in a wider field of view than a small one, enable* 

 the animal to find the object of its search more readily. 



