FLYING

, the progressive motion of a bird, or other winged animal, through the air.

The parts of birds chiefly concerned in Flying, are the wings and tail: by the former, the bird sustains and wafts himself along; and by the latter he is assisted in ascending and descending, to keep his body poised and upright, and steady. The wings are extended or stretched quite out, and then struck forcibly downwards against the air, which by its resistance raises the bird upwards; then to make another stroke, the wing, by means of its joints, readily closes in some degree, presenting the sharp edge of the pinion foremost to cut the air, and drawing the collapsed feathers after it like a flag, to diminish the resistance to the ascent as much as possible; the wing and feathers are then stretched out horizontally again, and another downward stroke made, which raises the bird still higher; and so on as far as he pleases, or as the density of the air will sustain him; performing those motions of the wings very rapidly, that the flight may be the quicker.

Artificial Flying, is that attempted by men, &c, by the assistance of mechanics.

The art of flying has been attempted by several persons in all ages. Friar Bacon, about 500 years ago, not only asserts the possibility of flying, but affirms that he himself knew how to make a machine with which a man might be able to convey himself through the air like a bird; and further adds, that it had been tried with success. Though the fact is to be doubted, if, as it was said, it consisted in the following method; viz, in a couple of large thin hollow copper globes, exhausted of air; which being much lighter than air, would sustain a chair on which a person might sit. Father Francisco Lana, in his Prodromo, proposes the same thing, as his own thought. He computes, that a round vessel of plate-brass, 14 feet in diameter, weighing 3 ounces the square foot, will only weigh 1848 ounces; whereas a quantity of air of the same bulk will weigh near 2156 ounces; so that the globe will not only be sustained in the air, but will carry with it a weight of 304 ounces; and by increasing the size of the globe, the thickness of the metal remaining the same, he adds, a vessel might be made to carry a much greater weight. But the fallacy is obvious: a globe of the dimensions he describes, as Dr. Hook observes, would not sustain the pressure of the air, but be crushed inwards. Indeed it is not probable that such a globe can be made of a thinness sufficient to float in the atmosphere after it is exhausted of air, and yet be strong enough to sustain the compressing force of the atmosphere. But for this purpose it seems that the globe should be silled with an air as elastic or strong as the atmofphere, and yet be very much lighter; such as has lately been used in the Mongolsiers and Balloons; the former of which is filled with common air heated, so as to be more elastic, and less heavy; and the latter with inflammable air, which is as elastic as the common air, with only about one tenth of its weight. And thus the idea of flying, or rather floating, in the air, has been lately realized by the moderns, using however a different sort of air. See Aerostation. |

The same author describes a machine for Flying, invented by the Sieur Besnier, a smith of Sable, in the county of Main. See Philos. Collec. numb. 1.

By the foregoing method however, at best, only a method of floating can be obtained, like a log floating in a current; but not of Flying, which consists in moving through the air, independent of any current; and which must be effected by something in the nature of wings. Attempts of this latter kind also have indeed been made by several persons of late years; but it does not appear that any of them have been attended with such success as to induce the authors of those attempts to make them public. The philosophers of king Charles the second's reign were much busied about this art; and the celebrated bishop Wilkins was so confident of success in it, that he says, he does not question but in future ages it will be as usual to hear a man call for his wings, when he is going a journey, as it is now to call for his boots.

The story of the flight of Dædalus is well known.

Flying Pinion, is part of a clock having a fly or fan with which to gather the air, and so bridle the rapidity of the clock's motion, when the weight descends in the striking part.

FOCAL Distance, the Distance of the Focus, which is sometimes understood as its distance from the vertex, as in the parabola; and sometimes its distance from the centre, as in the ellipse or hyperbola.