404 



B I 11 D. 



by llie upp ( r p;irt. In general, however, there is tl: 

 same gradations from the more perfect air biids to 

 the more perfivt swimmers, the last of which, espe- 

 cially tho-f which' inhabit the colder seas and do not 

 migrate far toward the equator in winter, abound in 

 down of the finest description. This down consists 

 partly of a second feather produced at the end of the 

 barrel or tubular part of the principal one, and partly 

 of a separate clothing, each particle of which has its 

 own insertion in the skin, and which has no distinct 

 shafts, or any of the common characters of feathers. 

 This down, whether produced on the feather or on 

 the skin, is always frizzly or flocculent, as well as soft. 

 It thus has no general direction, like the feathers, 

 but stands every way ; and thus is very elastic as 

 well as warm and light. 



The different apportionment of this downy part cf 

 their clothing to the several climates and elements in 

 which birds move, as well as to their habits, is very 

 remarkable ; and many of the swimming birds can 

 remain for days in water very little above freezing, 

 and yet sustain no inconvenience from the action 

 either of the cold or of the water. 



The feathers of birds are in themselves, to a con- 

 siderable extent, water-proof, and all birds are more 

 or less furnished with glands near the base of the tail 

 which secrete an oily liquid. This liquid the birds can 

 reach and extract with their bill and apply it to the 

 feathers, by drawing these between the mandibles. 

 This operation forms part of the process of preening 

 or trimming the feathers, in which birds occupy a 

 portion of their time. They do this for three pur- 

 poses to strain the water from such feathers as get 

 wet, to smooth the webs of such as get ruffled, and to 

 apply the oily secretion as occasion may require ; and 

 they also make use of the bill in removing those de- 

 cayed feathers which become incutnbrances instead 

 of being useful to the birds in their motions. The 

 structure and economy of feathers, with the changes 

 which they undergo from age, season, or climate, are, 

 however, much too extensive for being explained in 

 a general sketch ; and therefore we must refer to the 

 word FEATHER for the structure, and to the word 

 PLUMAGE for the economy and changes, confining 

 the remainder of this section to the enumeration of 

 the acting feathers and their auxiliaries in the wings 

 and the tails of birds. 



But as introductory to the notice of these, it may 

 not be improper to remark that, generally speaking, 

 the nearer that the clothing feathers of birds approxi- 

 mate to the form of flying feathers, the latter are 

 the more firm and perfect in their structure ; and 

 that this holds not only in different species of birds, 

 but in the plumage of the same species during its 

 progress to maturity. There is even a gradation 

 from the ordinary clothing feathers to the flying 

 ones through the medium of the coverts. 



In the wings, the bones, the hnmerus, the fore- 

 arm, the wrist, and the hand, are free. They, and 

 the muscles on them, are clothed to some extent 

 svith feathers similar to those on the body, arid par- 

 taking of the character of npper feathers above the 

 turn, and under feathers below it, passing imper- 

 ceptibly into each other on the turn itself. To these 

 succeed the several coverts, of which there are gene- 

 rally three rows, more or less distinct, and more or 

 less produced, according to the species, but gene- 

 rally increasing in length and strength as they ap- 

 proach the quills. These are called the lesser, the 



middle, ai.tl llic greater coverts, of the particular 

 quills, or portion of the wing to which they are 

 applied ; and there are similar coverts on tlio under 

 sides of the wings, only ihese are weaker, smaller 

 and more soft and downy in their texture, the 

 whole under side of the wing being so formed as to 

 take the greatest possible hold on the air, while the 

 upper side is formed for rising through the air with 

 the least possible resistance. 



The quills, or real feathers of flight in the wings, 

 are distinguished as primaries, secondaries, and ter- 

 tiaries, according to the place of the wing to which 

 j they are attached. . The primaries are attached to 

 the hand and wrist, forming the extremity of the 

 wing ; and they are, generally speaking, the longest 

 and the most powerfully supported by coverts. The 

 secondaries, which are shorter, are chiefly inserted on 

 the bones of the fore-arm ; and the tertiaries on the 

 humerus. In some birds the tertiaries are the shortest 

 quills in the wings ; but in others, and these are gerie- 

 , rally birds which have the habit of running swiftly, 

 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 wing. 



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 on 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 

 for swift motion. The emu is not so swift footed as 

 the ostrich, and the feathers upon it are all more 

 nearly of the same length and form. Judging from its 

 structure, for of its habits we know nothing, the apte- 

 ryx is but a slow moving bird, and the feathers upon 

 it are all pendent and flexible, resembling thatch as 

 much as they do ordinary feathers. 



The supplemental or ornamental feathers, of 

 which the uses are not well known, appear on 

 various parts of the body. They are generally 

 confined to the male birds, or at least most conspicu- 

 ous in them ; and in some instances, as in that of the 

 ruff, they make their appearance only during the 



