But Miette was mistaken this time, for Paul was now very anxious to learn more.
"Very well," said Monsieur Roger, "as all this has not wearied you, I am, in order to end to-day, going to make another experiment which will not be a bit tiresome, and which, without any scientific apparatus, without any air-pump, will demonstrate to you for the last time the existence of the pressure, of the weight of the atmosphere."
Monsieur Roger stopped and looked at Miette, whose good temper he was again going to put to the test. Then he said,--
"I need a carafe and a hard egg; and if Miss Miette will only be kind enough to----"
This time Miette seemed still more uneasy than ever, more embarra.s.sed, more uncomfortable; still, she fled rapidly towards the kitchen. During her absence, Monsieur Roger said to Madame Dalize,--
"Miette seems to think that I trouble her a little too often."
"That is not what is annoying her, I am certain," replied Madame Dalize; "but I do not understand the true cause. Let us wait."
At this moment Miette returned, with the carafe in one hand, the hard-boiled egg (it was not boiled very hard, however) in the other.
Monsieur Roger took the sh.e.l.l off the egg and placed the egg thus deprived of its sh.e.l.l upon the empty carafe, somewhat after the manner of a stopper or cork.
[Ill.u.s.tration]
"What I want to do," said he, "is to make this egg enter the carafe."
"Very well," said Miette; "all you have to do is to push from above: you will force the egg down."
"Oh, but n.o.body must touch it. It must not be a hand that forces it down, but by weight from above. No, the atmosphere must do this."
Monsieur Roger took off the egg, and lit a bit of paper, which he threw into the empty carafe.
"In order to burn," said he, "this paper is obliged to absorb the oxygen of the air in the carafe,--that is to say, it makes a partial vacuum."
When the paper had burned for some moments, Monsieur Roger replaced the egg upon the carafe"s neck, very much in the manner you would place a close-fitting ground-gla.s.s stopper in the neck of a bottle, and immediately they saw the egg lengthen, penetrate into the neck of the carafe, and at last fall to the bottom. "There," said he, "is atmospheric pressure clearly demonstrated. When a partial vacuum had been made in the carafe,--that is to say, when there was not enough air in it to counterbalance or resist the pressure of the exterior air,--this exterior air pressed with all its weight upon the egg and forced it down in very much the same way as Miss Miette wished me to do just now with my hand."
In saying these last words, Monsieur Roger looked towards Miette.
"By the way," he said, "I must apologize to you, Miss Miette, for having sent you on so many errands. I thought I saw that it annoyed you a little bit."
Miss Miette raised her eyes with much surprise to Monsieur Roger.
"But that was not it at all," said she.
"Well, what was it?" asked Monsieur Roger.
And Miette replied timidly, yet sweetly,--
"Why, I only thought that you might stop calling me Miss. If you please, I would like to be one of your very good friends."
"Oh, yes; with very great pleasure, my dear little Miette," cried Monsieur Roger, much moved by this touching and kindly delicacy of feeling, and opening his arms to the pretty and obliging little child of his friends.
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CHAPTER XVII.
WHY THE MOON DOES NOT FALL.
Next evening Monsieur Roger, as well as his friend Monsieur Dalize, seemed to have forgotten completely that there was such a thing as physical science. He sat in a corner and chatted about this thing and that with Monsieur and Madame Dalize. Still, the air-pump was there, and the children touched it, looked at it, and examined the different portions of it.
At last there was a conversation in a low tone between Paul and Miette, and in the midst of the whispering were heard these words, clearly p.r.o.nounced by the lips of Miette,--
"Ask him yourself."
Then Monsieur Roger heard Paul answer,--
"No, I don"t dare to."
Miette then came forward towards her friend Roger, and said to him, without any hesitation,--
"Paul asks that you will explain to him about the tower?"
Monsieur Roger remained a moment without understanding, then a light struck him, and he said,--
"Ah! Master Paul wants me to explain to him how I learned the height of the tower Heurtebize?"
"That is it," said Miette.
Paul Solange made an affirmative sign by a respectful movement of the head.
"But," said Monsieur Roger, responding to this sign, "it is physical science, my dear Master Paul,--physical science, you know; and, goodness, I was so much afraid of boring you that both I and Monsieur Dalize had resolved never to approach this subject."
"Still, sir," said Paul, "all that you have said and shown to us was on account of the tower of Heurtebize, and you promised me----"
"That is true," said Monsieur Dalize; "and if you promised, you must keep your word. So explain to Paul how you have been able, without moving, to learn the exact height of that famous tower."
"Come, then, I obey," answered Monsieur Roger.
And, addressing himself to Paul, he said,--
"You will remember that at the beginning of this conversation on gravity I took a little stone and let it fall from my full height. It produced a very feeble shock; but I made you remark that if it were to fall from a greater height the shock would be violent enough to break it."
"Yes," said Paul, "I remember."
"Then, of course, you understand that the violence of the shock of a body against a fixed obstacle depends upon the rate of speed this body possessed at the moment when it encountered the obstacle. The higher the distance from which the body falls, the more violent is the shock,--for its swiftness is greater. Now, the speed of a falling body becomes greater and greater the longer it continues to fall; and, consequently, in falling faster and faster it will traverse a greater and greater s.p.a.ce in a given interval of time. In studying the fall of a body we find that in one second it traverses a s.p.a.ce of sixteen feet and one inch. In falling for two seconds it traverses----"
"Twice the number of feet," said Miette, with a self-satisfied air.
"Why, no," said Paul; "because it falls faster during the second second, and in consequence travels a greater distance."