THE AUTHOR OF PARADISE LOST, Part I. THE AUTHOR OF PARADISE LOST, Part II. WEATHERING CAPE HORN, Part II. FROM the earliest ages, men have been so envious of the flight of birds, that they have tried to imitate their feathered friends, and endeavoured, like them, to skim at their ease through the atmosphere. But every effort has proved unavailing, from the time of 1Icarus, up to the 2" Flying Man," and every man-bird has 3 ignominiously failed in his attempt, some adventurers having lost their courage, some their limbs, and some their lives. And the reason of the failure may be readily ascertained. In the first place, the wings of birds are very much longer in proportion to their bodies, than are the arms of man. This is seen even in short-winged birds, such as the partridge or the sparrow, while the wings of the frigate bird or the albatross are so long that at a distance the bird appears to be all wing. Then again, these enormous wings must require corresponding muscles to work them; so that even if we could make wings of proportionate size, and fix them on our arms, we should still be as much tied to the earth as before, for want of the power to move them. Again, even if we had the requisite limbs and muscles, and had been furnished with a goodly array of feathers, our efforts at flight would be unavailing. We might possibly be able to descend from a height without injury, but we should not be able to ascend, and thus we should lose one of the principal objects of flight, while it would be perfectly impossible to transport our selves through the air. The reason of our failure lies principally in the construction of the human skeleton, together with the comparative imperfection of our organs of respiration. The bone of a bird is of a very different texture from that of man. It is hollow, contains air instead of marrow, and is throughout of a far more porous and spongy tex ture than the bone of man or of quadrupeds; and this texture is retained even when the bird is not intended to fly. It is well known that as the bone becomes older, its substance solidifies; and therefore we might be led to imagine that if a 7section of the leg-bone of an adult ostrich, a wingless, or rather a flightless bird, were placed under the microscope, it would present a much more solid and firm appearance than a similar section taken from a young 'mammal. But such is not the case; and the difference between the two is so great as to be evident to the unassisted eye: while if even a moderate magnifying power be brought to bear on them, the distinction is so clearly marked that the most inexperienced spectator will at once refer the two sections to different classes of animals. Into these hollow bones the air is forced from the lungs, and thus the body of the bird is rendered much lighter, bulk for bulk, than that of a mammal; and so plentiful is the supply of air conveyed through the bones, that respiration can be partially carried on even when the ordinary channels are stopped. This was discovered accidentally by a sportsman, who had shot a bird, which fell into the water. He had only wounded it, and in order to kill it easily, he held its head under the water into which it had fallen, as its plumage was already wet, and could not suffer more damage. But the bird had a particular objection to being drowned, and obstinately persisted in remaining alive, even though its head had been under water for thrice the time that would have drowned an ordinary bird. At last the cause of vitality was discovered in a shattered wing-bone, the broken extremity of which remained out of the water, thus affording a channel through which the bird continued to draw sufficient air to support life. Nor are birds the only animals whose bodies are thus 10 permeated by air. Every practical entomologist knows that the air-tubes which supply the place of lungs in insects are carried throughout the body, and even to the ends of the limbs, so that the legs and 12antennæ of an insect become organs of respiration, as well as of locomotion or touch. In the elaborate work on the 13anatomy of the common cockchafer, by Strauss Durckheim, a German naturalist, there is a drawing of the air-tubes and 14sacs that fill the interior of the insect. There are some birds which can still further increase the comparative bulk of their bodies by driving air into a series of cellular spaces between the skin and the muscles. Of this structure the common gannet, or Solan goose, is a familiar example, and by this power it attains that complete 15buoyancy which enables it to ride fearless and unharmed on the rough waves of a troubled sea. The enclosed air also benefits the bird in another way. When the gannet sees from its lofty height its finny prey, it proportions the rate of its descent to the size of the fish and its depth in the water. If the fish is small and near the surface, the bird sweeps over the waves, and snaps it up just as a swallow snaps up a fly; but if it is of tolerable size, and rather deep in the water, the gannet hurls itself headlong upon it, plunges into the water, driving up the spray like a cloud, and then emerges from the surface, bearing the prey in its beak. Now every one knows that if the hand is struck upon the water, the sensation is nearly as painful as if a board were struck; and those who are accustomed to dive from heights always take care to keep the body straight, and to join the hands over the head, so as to plough their way through the water, which otherwise would strike against the head with unpleasant violence. |