“If you imagine that the kite, under such circumstances, would fall upon the spot directly under it, you are much deceived: recollect that, if the string should snap, the kite would be abandoned to two forces, those of the wind, and its own gravity; and you will perceive that, under such circumstances, it could not obey either of them, but would fall in an intermediate or diagonal direction. This fact will be rendered apparent by the annexed diagram. B A may be supposed to represent the force and direction of the wind acting upon the kite, and B D those of its gravity; then it is evident that, under the influence of these joint forces, it would describe the diagonal, and, for reasons already explained, that line must necessarily be the curve B F.”
“Come,” said the vicar, “before Tom draws down his kite, let us send up a messenger.”
“What may that be?” asked Louisa.
“A piece of paper or pasteboard, which, on being introduced upon the string, is blown along the line up to the kite.”
The messenger was accordingly prepared, and being placed upon the string, it ascended as Mr. Seymour had anticipated. While this operation was in progress, the vicar stood earnestly gazing upon the kite, and, at length, burst forth in the following animated soliloquy:--
“Assuredly, this must be acknowledged as a most beautiful and imposing toy! Fastidious or insensible must be that person, who does not feel exhilarated as he gazes on the kite, proudly floating under the canopy of heaven, and reflecting the departing smiles of the evening sun, after it has ceased to cheer us below.”
“It has been said,” observed Mr. Seymour, “to the disparagement of kite-flying, that as soon as the machine has been raised into the air, and all the string let out, the excitement of the sport is at an end, and that as nothing further can be achieved, the interest of the performer from that moment begins to languish; now at this period the messenger will open a new source of pleasure and instruction, and may, by a little ingenuity, be made to afford a great diversity of amusement. I have therefore provided myself with several varieties of this machine. Here is one in the form of a dragon, which, as it ascends, produces a very striking and almost magical effect. See, there it goes!”
The children were delighted, for the string upon which it was carried became at a certain height invisible; so that the figure appeared like a monster hovering in the air.
“I will now show you a winged variety of this apparatus, which we will name the Brompton Messenger.[[44]] It consists of a hollow cylinder of stiff pasteboard, or thin wood, the diameter of which is sufficiently large to allow its free revolution round the string of the kite. To this cylinder are attached several flappers, or sails, in an oblique direction, like those of a windmill, each of which is covered with paper of a different colour. The action of the wind upon those oblique surfaces necessarily occasions a rapid rotation, upon a principle which I shall presently explain; and the beautiful effect thus produced, as the whirling body ascends, must be seen before it can be appreciated. I have some other contrivances of a similar nature, which it is my intention to prepare for your future amusement.”[(41)]