04 FEATHERS OF FLIGHT. 



with the wings partially extended, they are so much 

 longer than the secondaries that the bird has the 

 appearance of double wings, one set near the body 

 and a longer set farther off. The quills are usually 

 distinguished by numbers, as the first, second, and so 

 on, counted from the extremity of the \vinir. 



The tails of birds, like the wings, consist of pro- 

 duced feathers and coverts for their support, though 

 the feathers of flight in the tails do not get the name 

 of quills. 



Both the wings and the tails of birds vary much 

 in form, in magnitude, and in power of action ; 

 and though they are both concerned in the flight 

 of the bird, and partially also in its motions on land 

 or in the water, they do not vary according to the 

 same law, and therefore they do not indicate the 

 same habit. Still, however, as they are both con- 

 cerned in the flight, or other motion of the bird, 

 they must, in all their apparent discrepancies, be 

 the best adapted to each other. 



In those land birds which have not the power of 

 flight, such as the ostrich, the emu, the apteryx, 

 and a few others, none of the feathers have much 

 approximation to the character of flying feathers, 

 properly so called : they more resemble a peculiar 

 species of down, but still it is feathered down, and 

 the different portions are more minutely feathered in 

 their ramifications than even those of flying birds ; so 

 that all the produced feathers upon these species are 

 calculated for taking a powerful hold on the air ; 

 and the hold so taken no doubt helps to support 

 the birds as they walk along. This use of these 

 produced feathers is rendered more probable by 

 their being more conspicuous in proportion, as the 

 bird is longer on the legs and otherwise better fitted 



