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 THE STRUCTURE AND GENERAL CHARACTER OF PIGEONS. 5 the position of the different feathers of the wings with regard to the joints of its framework. Into that part of the wing formed of the bones of the hand, d to f, are inserted the flight-feathers of the fancier, the primaries of the naturalist. These are ten in number, the second being usually the longest, and the length diminishing regularly from it to the tenth. In some of the more artificial varieties, as the Short-faced Tumblers, the number of primaries is diminished to nine.

The secondaries are twelve in number, and take their rise from that part of the wing, c to d, which corresponds to our fore-arm. In some birds a third set of quill feathers, termed tertiaries, take their rise from the humerus b c, but these are not conspicuous in the pigeons. In describing the feathers of the wing, the bastard or spurious pinion e, attached to the rudimentary fore-finger g, must not be overlooked.

It is impossible to conceive any mechanical contrivance working more smoothly and effectively than the wing of a pigeon. When upon each quill feather is supported by, and in its turn supports, those adjacent to it; and thus is formed a concave under surface to strike the air in flight. In closing, each feather glides smoothly over its fellows, and the whole wing shuts up in the smallest possible compass, the primaries passing under the secondaries, so that only their ends are exposed. In flight, the bird raises the extended wing, and then strikes it against the air below with great force. The support of the bird in the air is due to the circumstance that the downward stroke is made with much greater force than that with which the wing is raised, and also to the form of the wing and the curvature of the feathers. The mode in which the forward flight of the bird is secured has been more correctly described by the Duke of Argyll, in his "Reign of Law," than by any other writer. His Grace writes:—

"The power of forward motion is given to birds, first by the direction in which the whole wing-feathers are set, and next by the structure given to each feather in itself. The wing-feathers are all set backwards, that is, in the direction opposite to that in which the bird moves, whilst each feather is at the same time so constructed as to be strong and rigid towards its base, and extremely flexible and elastic towards its end. On the other hand the front of the wing, along the greater part of its length, is a stiff hard edge, wholly unelastic and unyielding to the air. The anterior and posterior webs of each feather are adjusted on the same principle. The consequence of this disposition of the parts as a whole, and of this construction of each of the parts, is, that the air which is struck and compressed in the hollow of the wing, being unable to escape through the wing, owing to the closing upwards of the feathers against each other, and being also unable to escape forwards, owing to the rigidity of the bones and of the quills in this direction, finds its easiest escape backwards. In passing backwards it lifts by its force the elastic ends of the feathers; and thus, whilst effecting this escape, in obedience to the law of action and reaction, it communicates, in its passage along the whole line of both wings, a corresponding push forwards to the body of the bird. By this elaborate mechanical contrivance the same volume of air is