RAPIDITY OF FLIGHT. 



77 



cases, be too inconsiderable to make any material altera- 

 tion in the result, though, if greater accuracy is required, 

 it may be ob- 

 tained by the 

 usual mode of 

 measuring tri- 

 angles. Thus, 

 let B c be the 

 height 

 tower, 



of the 



and A 

 the point from 



whence the Starling rose, flying to the point B. Knowing 

 the height of the tower and the distance A c, we have 

 to calculate A B, which is easily learned, since by the 

 well-known problem of Euclid, AB 2 = A c 2 + B c 2 ; by 

 extracting the square root, we therefore find the exact 

 length of A B. 



It was by an application of this simple rule that the 

 flight of an Eagle was ascertained to be little short of 

 one hundred and forty miles an hour. The bird was 

 seen hastening on its way over a valley in the Pyrenees, 

 and the number of seconds was observed, which elapsed 

 between its passing from the summit of one high point, 

 till it reached the brow of a mountain on the other side, 

 the space between which was known by reference to a 

 good map, in which the distances were well laid down. 

 Such a rapid progress, we are aware, will scarcely be 

 credited; but a celebrated naturalist, in speaking of the 

 large white Fishing Eagle of North America, gives rea- 

 sons for suspecting that its speed is still greater: he 

 says, that, from an immense height, on perceiving their 

 prey, they glide downwards with such rapidity as to 

 cause a mighty rushing sound, not unlike that produced 

 by a violent gust of wind passing amongst the branches 

 of trees ; and that the fall of this bird, enormous as it 

 is, can on such occasions be scarcely followed by the 

 eye*. Those who ride over commons of fine turf, may 



* Audubon. 



