far exceeds the strength of his arms only; and by sitting in such a position, his strength can be exerted with a far greater force than in any other attitude whatever; he at the same time gains an additional advantage, in this plan of mine, by exerting his strength upon a lever.

The two greatest requisites for accomplishing the art of flying, are these; first, expansion of wings large enough to resist, in a sufficient degree, the specific gravity of whatever is attached to them; second, strength enough to strike the wings with a sufficient force to complete the buoyancy, and give a projectile motion to the machine. With these two requisites combined, flying must be accomplished; and, upon my plan, there can be no doubt of wings being made as large as ever they may be wanted; neither ought we to doubt of a man's ability, exerting himself in the way I have described, to bring into action as great a degree of strength, in proportion to his weight, as the condor is possessed of. Therefore, if

we are secure of these two requisites, and I am very confident we are, we may calculate upon the success of flying, with as much certainty as upon our walking.

When I first thought of artificial flying, it occurred to me, that it would be of some importance, to try what effect a pair of wings would have upon the air, without any mechanical power to work them; I thought that if I were to suspend a weight from beneath them, and they should prevent that weight from falling in a perpendicular line to the ground, they would demonstrate that the ideas I had conceived of the cause of the projectile motion of birds were well founded.

I therefore made the following experiment, to which I call the particular attention of my readers; as it positively demonstrates the cause of the projectile motion. I made a pair of small wings, of fine paper, and very small slips of wood to keep them extended, ́and fixed on a tail of the same materials, imitating,

as near as I could, the wings and tail of a bird, when expanded in a passive state. I then suspended a small weight from under them, with a piece of thread, exactly in the centre of gravity; I held them up as high as I could reach, then took away my hand and left them flat upon the air, without giving any impulse to them whatever; and by the weight pressing downwards, the air under the wings became in some degree compressed, and by its reaction against the under side and the back edges of the wings, they were projected with an oblique descent from one end of the room to the other, carrying the weight all that distance, which, without the wings being of this particular construction, could not have been done.

I had cause sufficient to exult in the success of my experiment, which proved to me, in a very satisfactory manner, that what I had conceived to be the cause of the projectile motion of birds, was really the cause, and that if I could but give a vertical motion to the wings, so that they might strike upon the air with

a sufficient force, they would then increase the reaction of the air, and instead of being projected in an oblique descent, totally over come their specific gravity, and continue flying in an horizontal direction.

This is an experiment which any of my readers may make trial of for their own satisfaction and amusement; and that they may be better able to comprehend me, I have given a representation of it in the plates annexed.Vide plate 3.

Another experiment, serving to shew the different effect of buoyancy obtained by a parachute, and by my paper wings, may be tried in the following manner. Take two straight sticks, neatly dressed, about the thickness of a crow-quill, and each about sixteen inches long, lay them across each other in the middle, at right angles, and tie them fast with a piece of thread; then tie a piece of thread from the ends of one stick to the other, so as to secure them at right angles; then take a

sheet of gauze paper, and fasten all the four corners of it to the four ends of the sticks; but previous to this, paste upon the four corners of the paper four small slips of thin cloth, in order to give sufficient strength; then suspend any small weight by a thread from the centre; let the whole fall from a height, and you will see the effect of a parachute in miniature: but this effect is very different from that of the paper wings; the parachute sinks gradually down in a perpendicular line, whilst the wings dart forwards to the distance of several yards.

1 have met with persons who have boldly asserted that it is impossible for a man to exert sufficient strength to raise himself up into the air by mechanical means alone; but the rashness and fallacy of such an assertion, is completely refuted and exposed by Mr. Degen, in Vienna, who has very lately actually ascended into the air, to a considerable height, by sitting in a machine and giving action to two parachutes; and had he properly understood the principles of birds' wings, and considered the

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