D333 G624 1852 vol. 2 A HISTORY OF THE EARTH AND ANIMATED NATURE. PART THIRD. HISTORY OF ANIMATED NATURE. BIRDS. HISTORY OF PART THIRD.-OF BIRDS. CHAP. I. OF BIRDS IN GENERAL. BOOK I. INTRODUCTORY. We are now come to a beautiful and loquacious race of animals, that embellish our forests, amuse our walks, and exclude solitude from our most shady retirements. From these man has nothing to fear; their pleasures, their desires, and even their animosities, only serve to enliven the general picture of nature, and give harmony to meditation. No part of nature appears destitute of inhabitants. The woods, the waters, the depths of the earth, have their respective tenants; while the yielding air, and those tracts of seeming space where man never can ascend, are also passed through by multitudes of the most beautiful beings of the creation. Every order and rank of animals seems fitted for its situation in life; but none more apparently than birds: they share, in common with the stronger race of quadrupeds, the vegetable spoils of the earth; are supplied with swiftness, to compensate for their want of force; and have a faculty of ascending into the air, to avoid that power which they cannot oppose. The bird seems formed entirely for a life of escape; and every part of the anatomy of the animal seems calculated for swiftness. As it is designed to rise upon air, all its parts are proportionably light, and expand a large surface with out solidity. As in mechanics the most curious instruments are generally the most complicated, so it is in anatomy. The body of man presents the greatest variety upon dissection; quadrupeds, less perfectly formed, discover their defects in the simplicity of their conformation; the mechanism of birds is still less complex; fishes are furnished with fewer organs still; whilst insects, more imperfect than all, seem to fill up the chasm that separates animal from vegetable nature. Of man, the most perfect animal, there are but three or four species; of quadrupeds, the kinds are more numerous; birds are more various still; fishes yet more; but insects afford so very great a variety, that they elude the search of the most inquisitive pursuer. Quadrupeds, as was said, have some distant resemblance in their internal structure with man; but that of birds is entirely dissimilar. As they seem chiefly formed to inhabit the empty regions of air, all their parts are adapted to their destined situation. It will be proper, therefore, before I give a general history of birds, to enter into a slight detail of their anatomy and conformation. As to their external parts, they seem surprisingly adapted for swiftness of motion. The shape of their body is sharp before, to pierce and make way through the air; it then rises by a gentle swelling to its bulk, and falls off in an expansive tail, that helps to keep it buoyant, while the fore-parts are cleaving the air by their sharpness. From this conformation, they have often been compared to a ship making its way through water; the trunk of the body answers to the hold, the head to the prow, the tail to the rudder, and the wings to the oars; from whence the poets have adopted the metaphor of remigium alarum, when they described the wavy motion of a bird in flight. In a comparative view with man, their formation seems much ruder and more imperfect; and they are in general found incapable of the docility even of quadrupeds. Indeed, what great degree of sagacity can be expected in animals whose eyes are almost as large as their brain? However, though they fall below quadrupeds in the scale What we are called upon next to admire in of nature, and are less imitative of human en- the external formation of birds is the neat posidowments; yet they hold the next rank, and far tion of the feathers, lying all one way, answering surpass fishes and insects, both in the structure of their bodies and in their sagacity. at once the purposes of warmth, speed, and security. They mostly tend backward, and are laid over one another in an exact and regular order, armed | bearded above. By this mechanism, the hooked with warm and soft down next the body, and more beards of one layer always lie next the straight strongly fortified, and curiously closed externally, beards of the next, and by that means lock and to fence off the injuries of the weather. But, lest hold each other. the feathers should spoil by their violent attrition against the air, or imbibe the moisture of the atmosphere, the animal is furnished with a gland behind, containing a proper quantity of oil, which can be pressed out by the bird's bill, and laid smoothly over every feather that wants to be dressed for the occasion. This gland is situated on the rump, and furnished with an opening or excretory duct; about which grows a small tuft of feathers somewhat like a painter's pencil. When, therefore, the feathers are shattered or rumpled, the bird, turning its head backwards, with the bill catches hold of the gland, and, pressing it, forces out the oily substance, with which it anoints the disjoined parts of the feathers; and drawing them out with great assiduity, recomposes and places them in due order; by which they unite more closely together. Such poultry, however, as live for the most part under cover, are not furnished with so large a stock of this fluid, as those birds that reside in the open air. The feathers of a hen, for instance, are pervious to every shower; on the contrary, swans, geese, ducks, and all such as Nature has directed to live upon the water, have their feathers dressed with oil from the very first day of their leaving the shell. Thus their stock of fluid is equal to the necessity of its consumption. Their very flesh contracts a flavour from it, which renders it in some so very rancid, as to make it utterly unfit for food; however, though it injures the flesh, it improves the feathers for all the domestic purposes to which they are usually converted. Nor are the feathers with which birds are covered less an object of admiration. The shaft of every feather is made proportionably strong; but hollow below for strength and lightness, and above filled with a pith to feed the growth of the vane or beard that springs from the shaft of the feather on either side. All these feathers are placed generally according to their length and strength, so that the largest and strongest feathers in flight have the greatest share of duty. The vane or beard of the feather is formed with equal contrivance and care. It consists not of one continued membrane; because, if this were broken, it could not easily be repaired; but it is composed of many layers, each somewhat in itself resembling a feather, and lying against each other in close conjunction. Towards the shaft of the feather, these layers are broad, and of a semicircular form, to serve for strength, and for the closer grafting them one against the other when in action. Towards the outer part of the vane, these layers grow slender and taper, to be more light. On their under-side they are thin and smooth, but their upper outer-edge is parted into two hairy edges, each side having a different sort of hairs, broad at bottom, and slender and The next object that comes under consideration, in contemplating an animal that flies, is the wing, the instrument by which this wonderful progression is performed. In such birds that fly, they are usually placed at that part of the body which serves to poise the whole, and support it in a fluid that at first seems so much lighter than itself. They answer to the fore-legs in quadrupeds, and at the extremity of this they have a certain finger-like appendix, which is usually called the bastard-wing. This instrument of flight is furnished with quills, which differ from the common feathers only in their size being larger, and also from their springing from the deeper part of the skin, their shafts lying almost close to the bone. The beards of these quills are broad on one side and more narrow on the other, both which contribute to the progressive motion of the bird, and the closeness of the wing. The manner in which most birds avail themselves of these, is first thus; they quit the earth with a bound, in order to have room for flapping with the wing; when they have room for this, they strike the body of air beneath the wing with a violent motion, and with the whole under surface of the same; but then to avoid striking the air with equal violence on the upper side as they rise, the wing is instantly contracted; so that the animal rises by the impulse, till it spreads the wing for a second blow. For this reason we always see birds choose to rise against the wind, because they have thus a greater body of air on the under than the upper side of the wing. For these reasons also large fowls do not rise easily; both because they have ¦ not sufficient room at first for the motion of their wings, and because the body of air does not lie so directly under the wing as they rise. In order to move the wings, all birds are furnished with two very strong pectoral muscles, which lie on each side of the breast-bone. The pectoral muscles of quadrupeds are trifling in comparison to those of birds. In quadrupeds, as well as in man, the muscles which move the thighs and hinder parts of the body are by far the strongest, while those of the arms are feeble: but in birds, which make use of their wings, the contrary obtains; the pectoral muscles, that move the wings or arms, are of enormous strength, while those of the thighs are weak and slender. By means of these, a bird can move its wings with a degree of strength, which, when compared to the animal's size, is almost incredible. The flap of a swan's wing would break a man's leg; and a similar blow from an eagle has been known to lay a man dead in an instant. Such, consequently, is the force of the wing, and such its lightness, as to be inimitable by art. No machines, that human skill can contrive, are capa |