BIRDS OF THE AIR. 177 



of down, like tliat wliicli surrounds the receptacle of a 

 ripened dandelion flower. When we watch the flight of 

 a short- winged bird like the Quail, the radiations formed 

 by the rapid motions of its wings make only a semicircle. 

 In the Humming-Bird they form a complete circle of 

 luminous rays. This flight, which resembles that of cer- 

 tain insects, is the more remarkable on account of the 

 extraordinary length of its wings, which would lead us to 

 infer that they would be incapable of such rapid motion 

 by the muscular force of so small a body. The wings of 

 those moths and beetles which have a similar movement 

 bear no proportion to the length of the Humming-Bird's 

 wing, compared with the size of the body of the insect and 

 of tlie bird. It is the rapid vibration of the wings, pro- 

 ducing a sound like the spinning of a top, that has given 

 to this family of birds the name by which they are desig- 

 nated. 



While hovering before a flower, this hum is plainly 

 audible ; but when the bird darts off to another place the 

 tone produced by these vibrations is plainly raised to a 

 higher key, as it spins like an arrow through the air. 

 Dr. Brewer, alluding to the Swiss philosopher Saussure, 

 says : " On the first visit of this naturalist to a savanna in 

 the island of Jamaica, he noticed what he at first took to 

 be a brilliant green insect, of rapid flight, approaching 

 him by successive alternations of movements and pauses, 

 and rapidly gliding among and over the network of inter- 

 lacing shrubs. He was surprised by the extraordinary 

 dexterity with which it avoided the movements of his 

 net, and yet more astonished to find, when he had cap- 

 tured it, that he had taken a bird and not an insect.'* 



The largest known Humming-Bird is about the size of 



the Chimney-Swallow ; and so great is the disparity in 



the size of the different species, that when confined in a 



cage, and the perch "has been occupied by the great 



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