ble of giving such force to so light an apparatus. The art of flying, therefore, that has so often and so fruitlessly been sought after, must, it is feared, for ever be unattainable; since as man increases the force of his flying machine, he must be obliged to increase its weight also.1

In all birds, except nocturnal ones, the head is smaller, and bears less proportion to the body than in quadrupeds, that it may more readily divide the air in flying, and make way for the body, so as to render its passage more easy. Their eyes also are more flat and depressed than in quadrupeds; a circle of small plates of bone, placed scalewise, under the outer coat of the or

1 The following interesting sketch of the power exerted by birds in their flight, and the demonstration of man's incapability of flying, is from the chap-gan, encompasses the pupil on each, to strengthen ter on Motion, in Carpenter's Animal Physiology.'

and defend it from injuries. Besides this, birds have a kind of skin, called the nictitating membrane, with which, like a vail, they can at pleasure cover their eyes, though their eye-lids continue open. This membrane takes its rise from the greater or more obtuse corner of the eye, and serves to wipe, cleanse, and probably to moisten its surface. The eyes, though they outwardly appear but small, yet separately, each almost equals the brain; whereas in man the brain is more than twenty times larger than the orbit of the eye. Nor is this organ in birds less adapted for vision by a particular expansion of the optic nerve, which renders the impressions of external objects more vivid and distinct.

Indeed

From this conformation of the eye it follows, that the sense of seeing in birds is infinitely superior to that of other animals. this piercing sight seems necessary to the creature's support and safety. Were this organ blunter, from the rapidity of the bird's motion, it would be apt to strike against every object in its way; and it could scarcely find subsistence unless possessed of a power to discern its food from above with astonishing sagacity. A hawk, for instance, perceives a lark at a distance which neither men nor dogs could spy; a kite, from an almost imperceptible height in the clouds, darts down on its prey with the most unerring aim. The sight of birds, therefore, exceeds what we know in most other animals, and excels them both in strength and precision.

"The degree in which the wings act in raising the body or in propelling it through the air, varies considerably in different animals, according to the way in which they are set. Thus, in birds of prey, which require a rapid horizontal motion, the surface of the wings is very oblique, so that they strike backwards as well as downwards, and thus impel the body forwards whilst sustaining it in the air. Such birds find a difficulty in rising perpendicularly; and can in fact only do so by flying against the wind, which then acts upon the inclined surface of the wings just as it does upon that of a kite. On the other hand the lark, quail, and such other birds as rise to great heights in a direction nearly vertical, have the wings so disposed as to strike almost directly downwards. It has been estimated that a swallow, when simply sustaining itself in the air, is obliged to use as much force to prevent its fall as would raise its own weight to a height of about twenty-six feet in a second. Hence we may form some idea of the enormous expenditure of force which must take place when the body is not only supported but raised and propelled through the air. The eider-duck is said to fly ninety miles in an hour, and the hawk one hundred and fifty. The swallow and swift pass nearly the whole of the long summer days upon the wing, in search of food for themselves and their helpless offspring; and the rapidity of their flight is such that they can scarcely traverse less than seven or eight hundred miles in that time, although they go but a short distance from home. The flight of insects is even more remarkable for its velocity in proportion to their size; thus a swallow, which is one of the swiftest-flying of the birds, has been seen to chase a dragon-fly for some time without success; the insect always keeping about six feet in advance of the bird, and turning to one side and the other so instantaneously, that the swallow, with all its powers of flight and tact in chasing insects was unable to capture it. If the preceding estimate of the power expended by a bird in sustaining itself in the air be correct, it may be easily proved that it would be impossible for a man to sustain himself in the air, by means of his muscular strength alone, in any manner that he is capable of applying it. It is calculated that a man of ordinary strength can raise 134 pounds to a height of 3 feet per second, and can continue this exertion for eight hours in the day. He will then exert a force capable of raising 381,600 pounds to a height of 34 feet; or one-eighth that amount, namely, 47,700 pounds, to the height of 26 feet,—which, as we have seen, is that to which a bird would raise itself in one second by the force it is obliged to exert in order to sustain itself in the air. Now if we sup- five minutes. There is no possible means, however, pose it possible that a man could by any means con- by which a man could thus concentrate the force of centrate the whole muscular power required for such eight hours' labour into the short interval in which a day's labour into as short a period as the accom- he would have to expend it when supporting himself plishment of this object requires, we might find the in the air. And we have elsewhere seen that by no time during which it would support him in the air, combination of mechanical powers can force be by simply dividing this amount by his weight, which created; as these only enable force to be more adwe may take to be 150 pounds. The quotient is vantageously applied. Hence the problem of human 318, which is the number of seconds during which flight will never be solved until some source of power the expenditure of a force that would raise 47,700 shall be discovered far surpassing that which his mus. pounds to a height of 26 feet will keep his body sup-cular strength affords, and so portable in its nature ported in the air; and this is but little more than as not materially to add to his weight."-ED

All birds want the external ear standing out from the head; they are only furnished with holes that convey sounds to the auditory canal. It is true, indeed, that the horned owl, and one or two more birds, seem to have external ears; but what bears that resemblance are only feathers sticking out on each side of the head, but no way necessary to the sense of hearing. It is probable, however, that the feathers encompassing the earholes in birds supply the defect of the exterior ear, and collect sounds to be transmitted to the

internal sensory. The extreme delicacy of this is obvious; and consequently, they have a much organ is easily proved by the readiness with | greater facility of taking a long and large inspiwhich birds learn tunes, or repeat words, and the ration. It is sometimes also seen that the windgreat exactness of their pronunciation. pipe makes many convolutions within the body of a bird, and it is then called the labyrinth; but of what use these convolutions are, or why the windpipe should make so many turnings within the body of some birds, is a difficulty for which no naturalist has been able to account.

The sense of smelling seems not less vivid in the generality of birds. Many of them wind their prey at an immense distance, while others are equally protected by this sense against their insidious pursuers. In decoys where ducks are caught, the men who attend them universally keep a piece of turf burning near their mouths, upon which they breathe, lest the fowl should smell them, and consequently fly away. The universality of this practice puts the necessity of it beyond a doubt, and proves the extreme delicacy of the sense of smelling, at least in this species of the feathered creation.

Next to the parts for flight, let us view the legs and feet ministering to motion. They are both made light, for the easier transportation through the air. The toes in some are webbed to fit them for the waters; in others they are separate, for the better holding objects, or clinging to trees for safety. Such as have long legs have also long necks, as otherwise they would be incapable of gathering up their food either by land or water. But it does not hold, however, that those who have long necks should have long legs, since we see that swans and geese, whose necks are extremely long, have very short legs, and these chiefly employed in swimming.

Thus every external part, hitherto noticed, 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.

This difference of the windpipe often obtains in animals that, to all appearance, are of the same species. Thus in the tame swan, the windpipe makes but a straight passage into the lungs ; while in the wild swan, which to all external appearance seems the same animal, the windpipe pierces through the breast-bone, and there has several turnings before it comes out again, and goes to enter the lungs. It is not to form the voice that these turnings are found, since the fowls that are without them are vocal; and those, particularly the bird just now mentioned, that have them, are silent. Whence, therefore, some birds derive that loud and various modulation in their warblings, is not easily to be accounted for; at least the knife of the anatomist goes but a short way in the investigation. All we are certain of is, that birds have much louder voices, in respect to their bulk, than animals of any other kind; for the bellowing of an ox is not louder than the scream of a peacock.

| In these particulars, birds pretty much resemble each other in their internal conformation; but there are some varieties which we should more attentively observe. All birds have, properly speaking, but one stomach; but this is very different in different kinds. In all the rapacious kinds that live upon animal food, as well as in some of the fish-feeding tribe, the stomach is peculiarly formed. The œsophagus, or gullet, in them, is found replete with glandulous bodies, which serve to dilate and macerate the food, as it passes into the stomach, which is always very large in proportion to the size of If we go on to examine birds internally, we the bird, and generally wrapped round with fat, shall find the same wonderful conformation fit-in order to increase its warmth and powers of diting them for a life in air, and increasing the sur-gestion. face by diminishing the solidity. In the first place, Granivorous birds, or such as live upon fruits, their lungs, which are commonly called the sole, corn, and other vegetables, have their intestines stick fast to the sides of the ribs and back, and differently formed from those of the rapacious can be very little dilated or contracted. But to kind. Their gullet dilates just above the breastmake up for this, which might impede their bone, and forms itself into a pouch or bag, called breathing, the ends of the branches of the wind-the crop. This is replete with salivary glands, pipe open into them, while these have openings which serve to moisten and soften the grain and into the cavity of the belly, and convey the air drawn in by breathing into certain receptacles are very numerous, with longitudinal openings, like bladders, running along the length of the which emit a whitish and a viscous substance. whole body. Nor are these openings obscure, or After the dry food of the bird has been madifficult to be discerned; for a probe thrust into cerated for a convenient time, it then passes into the lungs of a fowl will easily find a passage into the belly, where, instead of a soft moist stomach, as the belly; and air blown into the windpipe will in the rapacious kinds, it is ground between two be seen to distend the animal's body like a blad-pair of muscles, commonly called the gizzard, der. In quadrupeds this passage is stopped by covered on the inside with a stony ridgy coat, the midriff; but in fowls the communication and almost cartilaginous. These coats rubbing

other food which it contains.

These glands

against each other, are capable of bruising and attenuating the hardest substances, their action being often compared to that of the grinding teeth in man and other animals. Thus the organs of digestion are in a manner reversed in birds. Beasts grind their food with their teeth, and then it passes into the stomach, where it is softened and digested. On the contrary, birds of this sort first macerate and soften it in the crop, and then it is ground and comminuted in the stomach or gizzard. Birds are also careful to pick up sand, gravel, and other hard substances, not to grind their food as has been supposed, but to prevent the too violent action of the coats of the stomach against each other.

Most birds have two appendices, or blind-guts, which, in quadrupeds, are always found single. Among such birds as are thus supplied, all carnivorous fowl, and all birds of the sparrow kind, have very small and short ones; water-fowl and birds of the poultry kind, the longest of all. There is still another appendix observable in the intestines of birds, resembling a little worm, which is nothing more than the remainder of that passage by which the yolk was conveyed into the guts of the young chicken, while yet in the egg and under incubation.

diseases; and in fact, they have but few. There is one, however, which they are subject to, from which quadrupeds are in a great measure exempt; this is the annual moulting which they suffer; for all birds whatsoever obtain a new covering of feathers once a-year, and cast the old. During the moulting season, they ever appear disordered; those most remarkable for their courage, then lose all their fierceness; and such as are of a weakly constitution, often expire under this natural operation. No feeding can maintain their strength; they all cease to breed at this season; that nourishment which goes to the production of the young is wholly absorbed by the demand required for supplying the nascent plumage.

This moulting time, however, may be artificially accelerated; and those who have the management of singing birds frequently put their secret in practice. They enclose the bird in a dark cage, where they keep it excessively warm, and throw the poor little animal into an artificial fever; this produces the moult; his old feathers fall before their time, and a new set take place, more brilliant and beautiful than the former. They add, that it mends the bird's singing, and increases its vivacity; but it must not be concealed, that scarcely one bird in three survives the operation.

The outlet of that duct which conveys the bile into the intestines is, in most birds, a great way distant from the stomach; which may arise from The manner in which nature performs this the danger there would be of the bile regurgitat-operation of moulting is thus: the quill, or ing into the stomach in their various rapid motions, as we see in men at sea; wherefore their biliary duct is so contrived, that this regurgitation cannot take place.

All birds, though they want a bladder for urine, have large kidneys and ureters, by which this secretion is made, and carried away by one common canal. "Birds," says Harvey, "as well as serpents, which have spongy lungs, make but little water, because they drink but little. They therefore have no need of a bladder; but their urine distils down into the common canal, designed for receiving the other excrements of the body. The urine of birds differs from that of other animals: for, as there is usually in urine two parts, one more serous and liquid, the other more thick and gross, which subsides to the bottom; in birds, the last part is most abundant, and is distinguished from the rest by its white or silver colour. This part is found not only in the whole intestinal canal, but is seen also in the whole channel of the ureters, which may be distinguished from the coats of the kidneys by their whiteness. This milky substance they have in greater plenty than the more thin and serous part; and it is of a middle consistence, between limpid urine and the grosser parts of the fæces. In passing through the ureters it resembles milk curdled or lightly condensed: and being cast forth, easily congeals into a chalky crust."

From this simple conformation of the animal, it should seem that birds are subject to few

feather, when first protruded from the skin, and come to its full size, grows harder as it grows older, and receives a kind of periosteum or skin round the shaft, by which it seems attached to the animal. In proportion as the quill grows older, its sides, or the bony part, thicken; but its whole diameter shrinks and decreases. Thus, by the thickening of its sides, all nourishment from the body becomes more sparing; and, by the decrease of its diameter, it becomes more loosely fixed in its socket, till at length it falls out. In the meantime the rudiments of an incipient quill are beginning below. The skin forms itself into a little bag, which is fed from the body by a small vein and artery, and which every day increases in size till it is protruded. While the one end vegetates into the beard or vane of the feather, that part attached to the skin is still soft, and receives a constant supply of nourishment, which is diffused through the body of the quill by that little light substance which we always find within when we make a pen. This substance, which as yet has received no name that I know of, serves the growing quill as the umbilical artery does an infant in the womb, by supplying it with nourishment, and diffusing that nourishment over the whole frame. When, however, the quill is come to its full growth, and requires no further nourishment, the vein and artery become less and less, till at last the little opening by which they communicated with the quill becomes wholly obliterated; and the quill,

Nothing can exceed the patience of birds while hatching; neither the calls of hunger, nor the near approach of danger, can drive them from the nest. They are often fat upon beginning to sit, yet before incubation is over, the female is usually wasted to skin and bone. Ravens and crows, while the females are sitting, take care to provide them with food; and this in great abundance. But it is different with most of the smaller kinds: during the whole time, the male sits near his mate upon some tree, and soothes her by his singing; and often when she is tired takes her place, and patiently continues upon the nest till she returns. Sometimes, however, the eggs acquire a degree of heat too much for the purposes of hatching; in such cases, the hen leaves them to cool a little, and then returns to sit with her usual perseverance and pleasure.

In general, however, every bird resorts to hatch | dance. The large birds, and those of the aquatic in those climates and places where its food is kinds, choose places as remote from man as posfound in greatest plenty; and always at that sible, as their food is in general different from season when provisions are in the greatest abun- that which is cultivated by human labour. Some birds which have only the serpent to fear, build erection, and with the same precautions against their nests depending from the end of a small severe weather, when all necessity for such pro- bough, and form the entrance from below; being vision has ceased, and the usual temperature of the thus secured either from the serpent or the monseason rather requires coolness and a free circulation of air. The house sparrow will commonly build four key tribes. But all the little birds which live or five times in the year, and in a variety of situa- upon fruits and corn, and that are too often untions, under the warm eaves of our houses and our welcome intruders upon the fruits of human insheds, the branch of the clustered fir, or the thick dustry, in making their nests, use every precautall hedge that bounds our garden, &c.; in all which tion to conceal them from man. On the other places, and without the least consideration of site or season, it will collect a great mass of straw and hay, hand, the great birds remote from human sociand gather a profusion of feathers from the poultry-ety, use every precaution to render theirs inacyard to line its nest. This cradle for its young, cessible to wild beasts or vermin. whether under our tiles in March or in July, when the parent-bird is panting in the common heat of the atmosphere, has the same provisions made to afford warmth to the brood; yet this is a bird that is little affected by any of the extremes of our climate. The wood pigeon and the jay, though they erect their fabrics on the tall underwood in the open air, will construct them so slightly, and with such a scanty provision of materials, that they seem scarcely adequate to support their broods, and even their eggs may almost be seen through the loosely connected materials: but the goldfinch, that inimitable spinner, the Arachne of the grove, forms its cradle of fine mosses and lichens, collected from the apple or the pear-tree, compact as a felt, lining it with the down of thistles besides, till it is as warm as any texture of the kind can be, and it becomes a model for beautiful construction. The golden-crested wren, a minute creature perfectly unmindful of any severity in our winter, and which hatches its young in June, the warmer portion of our year, yet builds its most beautiful nest with the utmost attention to warmth; and inweaving small branches of moss with the web of the spider, forms a closely-compacted texture nearly an inch in thickness, lining it with such a profusion of feathers, that, sinking deep into this downy accumulation, it seems almost lost itself when sitting, and the young, when hatched, appear stifled with the warmth of their bedding, and the heat of their apartment; while the white-throat, the black-preservation. cap, and others, which will hatch their young nearly at the same period, or in July, require nothing of the kind. A few loose bents and goose-grass, rudely entwined, with perhaps the luxury of some scattered hairs, are perfectly sufficient for all the wants of these; yet they are birds that live only in genial temperatures, feel nothing of the icy gales that are natural to our pretty indigenous artists, but flit from sun to sun, and we might suppose would require much warmth in our climate during the season of ineubation; but it is not so. The greenfinch places its nest in the hedge with little regard to conceal ment; its fabric is slovenly and rude, and the materials of the coarsest kinds; while the chaffinch, just above it in the elm, hides its nest with cautious care, and moulds it with the utmost attention to order, neatness, and form. One bird must have a hole in the ground; to another a crevice in the wall, or a chink in a tree is indispensable. The bullfinch requires fine roots for its nest; the gray fly-catcher will have cobwebs for the outworks of its shed. All the parus tribe, except the individual abovementioned, select some hollow in a tree, or cranny in a wall; and sheltered as such places must be, yet will they collect abundance of feathers and warm materials for their infants' bed. Endless examples might be found of the dissimilarity of requirements in these constructions among the several associates

So great is the power of instinct, in animals of this class, that they seem driven from one appetite to another, and continue almost passive under its influence. Reason we cannot call it, since the first dictates of that principle would be self

"Take a brute," says Addison,

"out of his instinct, and you find him wholly deprived of understanding. With what caution," continues he, "does the hen provide herself with a nest in places unfrequented, and free from noise and disturbance! When she has laid her eggs in such a manner that she can cover them, what care does she take in turning them frequently, that all parts may partake of the vital warmth! When she leaves them, to provide for her necessary sustenance, how punctually does she return before they have time to cool, and become incapable of producing an animal! In the summer you see her giving herself greater freedoms, and quitting her care for above two of our groves, our hedges, and our houses; and yet the supposition cannot be entertained for a moment that they are superfluous, or not essential for some purpose with which we are unacquainted. By how many of the ordinations of Supreme Intelligence is our ignorance made manifest! Even the fabrication of the nests of these little animals exceeds our comprehension; we know none of the causes or motives of that unembodied mind that willed them thus."Journal of a Naturalist