“It appears to me that flying is an easy process,” said Tom; “could we not contrive some sort of flapper, by which we might be able to rise into the air?”
“Your opinion, my dear boy, is by no means singular; hundreds have entertained the same belief before you; and so confident was the famous Bishop Wilkins, that he declared it to be his conviction, that, in future ages, it will be as usual to hear a man call for his wings, as it is now to call for his boots.”
“Yes,” said the vicar; “and if my memory is correct, William of Malmesbury, in his account of the Conquest of England by the Normans, mentions a Benedictine monk, by the name of Elmer, who having affixed wings to his hands and feet, ascended a lofty tower whence he took his flight, but he fell to the ground and broke both his legs.”
“I do not see the difficulty,” exclaimed Tom.
“The weight of our bodies is so great, that we have not sufficient muscular strength to impart a blow to the air that shall be equal to it. Now are you satisfied?” said his father.
“I am perfectly satisfied, if that be the case, that we can never hope to fly.”
“The principle, however, which I have just explained,” observed Mr. Seymour, “although it will fail us in our attempts to construct wings, is nevertheless extensively applicable in mechanics. A vane or fly, for instance, by resisting the air as it spins round, becomes the regulator of machinery. The intervals between the strokes on the bell of a clock are thus regulated, and the fly, on this occasion, is so contrived that this interval may be altered, or the clock made to strike faster or slower, by presenting the arms of it more or less obliquely to the direction in which they move. The same kind of fly is the regulator used in musical boxes, as I will presently show you, and indeed in almost all mechanical toys. Let us now return to the subject of the kite; for, as yet, we have merely considered the effect of increasing the wind upon its surface; we have next to enquire how the wind operates in raising it into the air.--Do you not remember, when I adjusted the noose in the belly-band, I stated that much depended upon this part of the apparatus? You will, at once, perceive that it will influence the angle which the kite forms with the earth, and I am about to prove to you, that the theory of the kite’s ascent is materially connected with the value of this angle; but, in order to render my explanation intelligible, I have prepared a diagram, to which I am desirous of directing your attention.
“The kite here appears in the act of rising from the ground; the line W will represent the direction of the wind blowing upon it, all the currents of which we will suppose united in one; it is evident, from what has been already stated, that as it falls upon an oblique surface, it will be resolved into two forces, viz. into one parallel with it, and into another perpendicular to that surface; of which the force represented by the line Y will alone produce any effect, carrying the kite along the line O A, or in a direction parallel to itself; and you must have observed that this was the direction in which the kite was impelled, when you suffered it to rise, without checking its progress by the string.”
“I remember that well,” said Tom; “and I also observed that, when I pulled my string, the kite immediately rose more perpendicularly.”