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 without solidity. 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 of nature, and are less imitative of human endowments, yet they hold the next rank, and far surpass fishes and insects, both in the structure of their bodies and in their sagacity. 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 describe the wavy motion of a bird in flight.* THE STRUCTURE OF BIRDS.-Birds may be said to constitute an isolated class of beings. They are distinguished by certain characters from all other animals: their classification does not pass into any other, and cannot, therefore, be consistently introduced into the supposed chain or gradation of naural bodies. The skeleton or bony frame of birds is in general lighter than in quadrupeds. They have the largest bones of all animals in proportion to their weight; and their bones are more hollow than those of animals that do not fly: air-vessels also enable them to blow out the hollow parts of their bodies, when they wish to make their descent slower, rise more swiftly, or float in the air. The spine is immovable, but the neck has a greater number of bones (never less than nine, and varying from that to twenty-four), and conse What we are called upon next to admire in the external formation of birds, is the neat position of the feathers, lying all one way, answering 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 with warm and soft down next the body, and more strongly fortified and curiously closed externally, to fence off the injuries of the weather. But, lest 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 disjointed 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 quently of joints, and more varied motion, than in quadrupeds. The breast-bone is very large, with a prominent keel down the middle, and is formed for the attachment of very strong muscles: the bones of the wings are analogous to those of the fore legs in quadrupeds, but the termination is in three joints or fingers only, of which the exterior is very short. This will be better understood by the annexed (Skeleton of a Turkey.) The muscles that move the wings downwards, in many instances, are a sixth part of the weight of the whole body; whereas those of a man are not in proportion one hundredth part so large. The centre of gravity of their bodies is always below the insertion of their wings to prevent them falling on their backs, but near that point on which the body is, during flight, as it were, suspended. The positions assumed by the head and feet are frequently cal culated to accomplish these ends, and give to the wings every assistance in continuing the progressive motion. The tail also is of great use, in regulating the rise and fall of birds, and even their lateral movements. What are commonly called the legs are analogous to the hind legs in quadrupeds, and they terminate, in general, in four toes, three of which are usually directed forwards, and one backwards; but in some birds there are only two foes, in others three. Birds exceed quadrupeds in the quantity of their respiration, for they have not only a double circulation, and an aerial respiration, but they respire also through other cavities beside the lungs, the air penetrating through the whole body, and bathing the branches of the aorta, or great artery of the body, as well as those of the pulmonary artery. Birds are usually classed according to the forms of their bills and feet, from those parts being connected with their mode of life, food, &c. and influencing their total habit very materially. MIRROR, vol. xix. *GLAND OF THE RUMP.-The greater number of authors tell us that birds, and more particularly aquatic birds, dress their feathers with a peculiar oil furnished for this purpose by a gland on the rump; but this is an opinion which we shall presently see admits of considerable doubt. It may be well, however, to state the particulars of the common notion. "Upon the rump," says Willughby, "grow two glandules, designed for the preparation and secretion of a certain unctuous humour, and furnished with a hole or excretory vessel. About this hole grows a tuft of small feathers or hairs, somewhat like to a painter's pencil. When, therefore, the parts of the feathers are shattered, ruffled, or 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. Every external part of the bird race appears adapted to the life and situation of the animal; nor are the inward parts, though less immediately appropriated to flight, less necessary to safety. The bones of every part of the body are extremely light and thin; and all the muscles, except that immediately moving the wings, extremely slight and feeble. The tail, which is composed of quill feathers, serves to counterbalance the head and neck-it guides the animal's flight like a rudder, and greatly assists it either in its ascent or when descending. any way discomposed, the bird, turning her head backward to her rump, with her bill catches hold of the fore-named tuft, and pressing the glandules, forces out the oily pap, and therewithal anointing the disjoined parts of the feathers, and drawing them out with her bill, recomposes and places them in due order, and causes them to stick faster together." "The glands which secrete the oil," says Blumenbach, "on the upper part of the tail, are largest in aquatic birds; in some of which, as the Muscovy duck (Anas moschata), the secreted substance has a musklike odour." The statement just given from Willughby is adopted by most of the systematic writers, though a few of them take no notice whatever of the existence of the rump glands. "On the back," we are told by Linnæus, "or upper surface of the rump, there are two glands which secrete an oily fluid, with which the birds anoint their feathers." "The lower part of the back," says Dr. Latham," is furnished with a double gland, secreting an oily fluid for the use of dressing the feathers." The recent authors who adopt this opinion would appear, from their taking no notice of them, to be unacquainted with the observations of M. Reaumur, which we shall abstract. The glands on the rump, he remarks, secrete an unctuous fluid, discharged in some birds by one, and in others by two excretory canals. Poultry have but one of these canals, which consists of a conical fleshy pipe of a series of rings, placed almost perpendicularly to the rump; and when this gland is pressed by the fingers, the fluid, thickish in consistence, is seen to exude. But in a peculiar species of barn-door fowls, without tails, (Gallus ecaudatus, TEMMINCK,) originally it would appear from Ceylon, the tail, the rump, and the gland are all wanting, the part where these grow in other species being depressed and smooth. Were an attempt made to assign a reason why these Ceylonese fowls have no unctuous gland on the rump, a mistake might as readily be committed as has, it would appear, been done in the theory framed to account for the use of the gland in birds which pos sess it. All the works of nature being lavishly filed with wonders, fitted to raise most just admiration of the Creator, those who, with very laudable intentions, undertake to exhibit these wonders, may be considered as in some degree blameable when they introduce into their enumeration circumstances that are vague and uncertain. Among such doubtful things appears to be the opinion that the feathers of birds require to be done over with a kind of oil or grease, in order to cause the rain or other water to run off without penetrating them, the unction, when wanted, being supplied by the gland on the rump. If those who adopt this opinion, plausible as it seems to be, had taken the trouble to ascertain the small quantity of fluid actually secreted by this gland from day to day, and compared it with the proportional extent of surface constituted by the assemblage of the numberless feathers of any particular bird, not to speak of the instrument with which the dressing is said to be effected, they would have seen at once that the theory is untenable, as the quantity secreted in one day would scarcely suffice to anoint a single feather, much less the whole. We have just squeezed out all the oil contained in the double rump gland of a common wren, and found it impossible to make it go over one of the tail feathers. "One fact," says M. Le Vaillant, " is frequently sufficient to demolish a theory;" and the fact that the feathers of the rumpless fowls which have no gland, are as smooth and proof against rain as those which possess the gland, furnishes a striking illustration of the remark. The fact, however, is unquestionable that birds are sometimes seen pecking about the gland in question. But the observing of a bird thus engaged, so far from authorizing the received conclusion, might have shown that the point of the bill could never squeeze out enough of fluid for the purpose alleged. The only legitimate inference would have been, that some slight pain or irritation had caused the bird to peck the gland; and every schoolboy knows that the canal of this gland often becomes obstructed in his pet birds, and occasions a troublesome and sometimes fatal engorgement. The remark of Blumenbach that the gland is largest in aquatic birds, contains a generalization not warranted by facts; for grebes, |