86 POWERFUL VISION OF THE EAGLE. 



which the eagle preys, are well acquainted with its 

 shadow ; and that, to prevent that from being seen, the 

 eagle floats at such a height as to make it indistin- 

 guishable. Certainly, we have always discovered the 

 eagle flying lower in cloudy weather than when the 

 sun was bright, but, whether on account of its answering 

 her vision better, or for some wise purpose, as that of 

 the shadow, has not been ascertained. 



From the summit of the mountain, if one be pro- 

 vided with Dollond's best three-feet achromatic tele- 

 scope, an instrument that no traveller in these lands of 

 long views should be without, the golden eagle can 

 be followed, and her motions watched, with the same 

 accuracy as if one were a companion in her flight. In 

 this we have a very apt and striking instance of the 

 superiority of reason over even the surest instinct, and 

 the finest apparatus with which it can be furnished. 

 The eye of the eagle is so formed, that, while the bird 

 floats in the air at such an elevation as that its size 

 is reduced to a single speck, it can command miles 

 of surface with such precision as to perceive at once 

 in what part of the wide field of view there is prey 

 even though nature, equally attentive to the prey and 

 the preyer, has coloured the former so like the surface 

 on which it is found, that no eye, but that of an eagle, 

 could distinguish it at even half the distance. 



But wonderful as that faculty is, it is less surprising 

 than human vision aided by the telescope, by means of 

 which man has been enabled not only to connect 

 mountain with mountain, but planet with planet ; and, 

 while he has his home localised in some little spot of 

 the earth, to become a dweller, as it were, in the whole 



