body, and prevents its being precipitated to the ground; such is the effect of the wings and tail when in a passive state.

I will next take some notice of the quill feathers, which are replete with proofs of the wisdom of the almighty artist who made them. As they were intended to swim with in so light and subtle a fluid as the air is, it was necessary that they should be formed of the lightest materials imaginable; and as they were intended to strike upon the air with great power and rapidity, it was requisite that they should possess, in the shafts, great strength with elasticity; it was expedient too, that the quill feathers should separate and open, to let the upper air pass through the wings, to facilitate their ascent, when they are struck upwards; it was also necessary that they should all shut close together, forming each wing into a complete surface or web, when they are, by the muscular power of the bird, forced down, in order to give a more secure hold upon the air below, and by that means keep the bird up.

Now if we do but examine the quill feathers, we shall find in the shafts astonishing strength with elasticity, and very little specific gravity indeed. The webs of the quill feathers are broader on one side of the shafts than the other, which causes them to open as the wings move up, and to shut as they come down, exactly answering the purposes I have already mentioned; therefore, we see how wonderfully complete the wings are in all their parts, and how effectually they serve all the uses required.

I will now shew the application and effect of the wings and tail in an active state. When a bird, by the power of its pectoral and deltoid muscles, puts its wings into action, and strikes them downwards in a perfectly vertical direction upon the air below, that air being compressed by the stroke of the wings, makes a resistance, by its elastic power, against the under side of the wings, in proportion to the rapidity of the stroke and the dimensions of the wings, and forces the bird upwards; at the same time, the back edges of the wings being

more weak or elastic than the fore edges, they give way to the resisting power of the compressed air, which rushes upwards past the same back edges, acting against them with its elastic power, and thereby causes a projectile force, which impels the bird forwards; thus we see that by one act of the wings the bird produces both buoyancy and progression. When the tail is forced upwards, and the wings are in action, the bird ascends, and forced downwards it consequently descends; but the most important use of the tail is to support the posterior weight of the bird, and to prevent the vacillation of the whole.

Thus having discovered and explained to my readers, the natural mechanical means by which birds accomplish flying, they will be able to see that the plan upon which I have formed my scheme for artificial flying, is perfectly analogous to the principles of nature, which certainly ought to be clearly understood, and taken as our only guide, before we can

ever expect to arrive at success in the art of flying; but with the knowledge of these principles, there cannot remain a doubt of

success.

When we first think of a man attempting to fly by mechanical means, we are induced, considering his specific gravity, to pronounce it impossible; and had we never seen or known of any bird larger than a humming bird, whose weight does not exceed one drachm, and whose diminutive wings measure only three inches from tip to tip; and were to be told by some traveller, that he had seen a bird with a body as large as a sheep, that had wings of twelve feet expansion, and that it could quit the earth, and ascend into the air with its ponderous body, and there fly about with as much ease as the little humming bird; we should think it too marvellous a tale to be credited. But as we are accustomed to see, almost every day, birds of such various dimensions and cific gravity, as are exhibited by nature, from the humming bird to the common wren; from

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the wren, through a numerous gradation, up to the eagle, we can readily give credit to the history of the wonderful condor, in South America, whose existence is so well attested that we can have no reason to doubt of it; more especially as we witness so vast a gradation in the indigenous birds of our own country. I believe that there were two of these prodigious birds in the Leverian Museum.

The following observations upon the wonderful difference in the weight of some birds, with their apparent means of supporting it in their flight, may tend to remove some prejudices against my plan, from the minds of some of my readers. The weight of the humming bird is one drachm, that of the condor not less than four stone; now if we reduce four stone into drachms, we shall find the condor is 14,336 times as heavy as the humming bird. What an amazing disproportion of weight! Yet, by the same mechanical use of its wings, the condor can overcome the specific gravity of its body with as much ease as the little humming bird.