Part 14 (1/2)

”Clouds, you doubtless know, are ma.s.ses of vapor from water. Now, when these vapors are sufficiently condensed to acquire a certain weight, they can no longer float in the atmosphere, and they fall in the form of rain. But they fall in rain because they have to traverse the air in order to fall to the ground. Now, the air offers such a resistance to this water that it is obliged to separate, to divide itself into small drops. If there were no air between the water and the ground, the water would not fall in drops of rain, but in a ma.s.s, like a solid body; and I am going to prove that to you, so as to convince Miss Miette.”

Among the various instruments unpacked from the box, Monsieur Roger chose a round tube of gla.s.s, closed at one end, tapering, and open at the other end. He introduced into this tube a certain quant.i.ty of water so as to half fill it. Then he placed the tube above a little alcohol lamp, and made the water boil.

”Remark,” said he, ”how fully and completely the vapors from the water, which are formed by the influence of heat, force out the air which this tube encloses in escaping by the open end of the tube.”

When Monsieur Roger judged that there no longer remained any air in the tube, he begged Monsieur Dalize to hand him the blowpipe. Monsieur Dalize then handed to his friend a little instrument of bra.s.s, which was composed of three parts,--a conical tube, furnished with a mouth, a hollow cylinder succeeding to the first tube, and a second tube, equally conical, but narrower, and placed at right angles with the hollow cylinder. This second tube ended in a very little opening.

Monsieur Roger placed his lips to the opening of the first tube, and blew, placing the little opening of the second tube in front of the flame of a candle, which Monsieur Dalize had just lit. A long and pointed tongue of fire extended itself from the flame of the candle.

Monsieur Roger placed close to this tongue of fire the tapering and open end of the tube in which the water had finished boiling. The air, forced out of the blowpipe and thrust upon the flame of the candle, bore to this flame a considerable quant.i.ty of oxygen, which increased the combustion and produced a temperature high enough to soften and melt the open extremity of the tube, and so seal it hermetically.

”I have,” said Monsieur Roger, ”by the means which you have seen, expelled the air which was contained in this tube, and there remains in it only water. In a few moments we will make use of it. But it is good to have a comparison under your eyes. I therefore ask Miss Miette to take another tube similar to that which I hold.”

”Here it is,” cried Miette.

”Now I ask her to put water into it.”

”I have done so.”

”Lastly, I ask her to turn it over quickly, with her little hand placed against its lower side in order to prevent the water from falling upon the floor.”

Miss Miette did as she was commanded. The water fell in the tube, dividing itself into drops of more or less size. It was like rain in miniature.

”The water, as you have just seen,” said Monsieur Roger, ”has fallen in Miss Miette's tube, dividing itself against the resistance of the air.

In the tube which I hold, and in which there is no longer any air, you will see how water falls.”

Monsieur Roger turned the tube over, but the water this time encountered no resistance from the air. It fell in one ma.s.s, and struck the bottom of the tube with a dry and metallic sound.

”It made a noise almost like the noise of a hammer,” said Paul Solange.

”Exactly,” answered Monsieur Roger. ”Scientists have given this apparatus the name of the water-hammer.” And looking at Miette, who in her astonishment was examining the tube without saying anything, Monsieur Roger added, smiling, ”And this hammer has struck Miss Miette with surprise.”

[Ill.u.s.tration]

[Ill.u.s.tration]

CHAPTER XVI.

AMUSING PHYSICS.

Hearing Monsieur Roger's jest, Miette raised her head, and said,--

”Yes, it is very curious to see water fall like that, in a single ma.s.s; and, besides, it fell quicker than the water in my tube.”

”Of course: because it did not encounter the resistance of the air. This resistance is very easy to prove; and if Miss Miette will give me a sheet of any kind of paper----”

Miss Miette looked at Monsieur Roger, seeming to be slightly nettled,--not by the errand, but by something else.

Then she went in search of a sheet of letter-paper, which she brought back to Monsieur Roger. He raised his hand and dropped the paper.