Great Exhibition o/1851. 143 



The barbules are given off from either side of the barbs, and are 

 sometimes similarly barbed themselves, as may be seen in the 

 barbules of the long feathers of the peacock's tail. 



The barbules are commonly short and close set, and curved in 

 contrary directions ; so that two adjoining series of barbules inter- 

 lock together, and form the mechanism by which the barbs are 

 compacted into the close and resisting vane of the quill, or "fea- 

 ther," properly so called. When the barbules are long and loose, 

 they characterise that form of the feather which is properly called 

 a " plume ;" and such are the most valuable products of the 

 plumage of birds in a commercial point of view ; as, for example, 

 the plumes of the ostrich. 



The lower barbs in every kind of feather are usually loose, 

 forming the down, which is increased, in most birds, by what is 

 called the " accessory plume." This is usually a small downy 

 tuft, but varies in different species, and even in the feathers of 

 different parts of the body of the same bird. The value of fea- 

 thers, for bed-stuffing, depends upon the proportion of loose soft 

 down that enters into their composition ; and as the " accessory 

 plume" in the body-feathers of the swan, goose, and duck, is 

 almost as long as the feather from which it springs, hence arises 

 the commercial value of the feathers of these aquatic birds. 



In the development of plumage, the first covering of the bird is 

 a temporary one, consisting of bundles of long loosely-barbed fila- 

 ments, which diverge from a small quill, and on their first appear- 

 ance are enveloped in a thin sheath, which soon crumbles away 

 after being exposed to the atmosphere.* These down feathers are 

 succeeded by the true feathers ; to which they bear the same rela- 

 tion as wool does to hair, or the temporary to the permanent teeth. 

 In most birds, a certain proportion of the down feathers is retained 

 with the true feathers, and this proportion is usually greatest in 

 aquatic birds. It is most remarkable in the Eider Duck [Anas 

 mollis sima), which may be compared with the sheep in regard to 

 the quantity and quality of the softer and warmer kind of the epi- 

 dermal covering. The down of the eider combines with its pecu- 

 liar softness, fineness, and lightness, so great a degree of elasticity, 

 that the quantity of this beautiful material which might be com- 

 pressed and concealed between the two hands of a man, will serve 

 to stuff the coverlet of a bed. 



All the varieties and modifications of the plumage of birds, ser- 

 viceable in manufactures, or valued as ornaments, might be com- 

 pared and studied with advantage in the Great Exhibition. 



* A good account of the mode of formation of feathers is given in a paper 

 by M. F. Cuvier, entitled " Sur le developpement des Plumes," in the " Me- 

 moires du Museum," torn. x. 10 ; or the article " Aves," in the " Cyclopedia of 

 Anatomy," may be consulted. 



