206 TEE LIFE OF THE FIELDS. 



the moment lie pauses gravitation exercises a force 

 much greater that when he glides. 



While hovering there are several forces balanced : 

 first, the original impetus onwards; secondly, that of 

 the depressed tail dragging and stopping that onward 

 course ; thirdly, that of the wing beating downwards ; 

 and fourthly, that of the wing a very little reversed 

 beating forwards, like backing water with a scull. 

 When used in the ordinary way the shape of the 

 wing causes it to exert a downward and a backward 

 pressure. His slip is when he loses balance : it is 

 most obviously a loss of balance; he quite oscillates 

 sometimes when it occurs ; and now and then I 

 have seen a kestrel unable to catch himself, and 

 obliged to proceed some distance before he could 

 hover again. Occasionally, in the slip he loses a foot 

 or so of elevation, but not always. While actually 

 hovering, his altitude does not vary an inch. All 

 and each of these movements and the considerations 

 to which they give rise show conclusively that the 

 act of hovering is nothing more or less than an 

 act of balancing; and when he has his balance he 

 will rest a moment with outstretched wings kept still. 

 He uses his wings with just sufficient force neither 

 to rise nor fall, and prevents progress by a slightly 

 different stroke. 



The next point is, Where does he hover? He 

 hovers any and everywhere, without the slightest 

 choice. He hovers over meadows, cornfields; over 

 the tops of the highest downs, sometimes at the very 

 edge of a precipice or above a chalk quarry ; over 

 gardens, waste ground ; over the highway ; over 



