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 mass;and, besides, it fell quicker than the water in my tube."
"Of course: because it did not encounter the resistance of the air. Thisresistance is very easy to prove; and if Miss Miette will give me asheet of any kind of paper----"
Miss Miette looked at Monsieur Roger, seeming to be slightlynettled,--not by the errand, but by something else.
Then she went in search of a sheet of letter-paper, which she broughtback to Monsieur Roger. He raised his hand and dropped the paper.Instead of falling directly towards the earth, as a piece of lead orstone would do, it floated downward from the right to the left, gentlybalanced, and impeded in its fall by the evident resistance of the air.When this bit of paper had at last reached the ground, Monsieur Rogerpicked it up, saying,--
"I am going to squeeze this bit of paper in such a way as to make it apaper ball; and I am going to let this paper ball fall from the sameheight as I did the leaf."
The paper ball fell directly in a straight line upon the floor.
"And yet it was the same sheet," said he, "which has fallen so fast. Thematter submitted to the action of gravity remains the same; there can beno doubt on that point. Therefore, if the sheet of paper falls morequickly when it is rolled up into a ball, it is certainly because itmeets with less resistance from the air; and if it meets with lessresistance, it is because under this form of a ball it presents only asmall surface, which allows it easily to displace the air in order topass."
"That is so," said Miss Miette, with a certainty which made every onesmile.
Miette, astonished at the effect which she had thus produced, looked ather friend Paul, who remained silent, but very attentive.
"Well, Paul," said she, "is not that certain?"
"Yes," answered Paul.
"Hold," returned Monsieur Roger. "I am going to show you an examplestill more convincing of the resistance of the air,--only I must have apair of scissors; and if Miss Miette will have the kindness to----"
Miss Miette looked again at Monsieur Roger with a singular air. None theless, she ran off in search of the scissors. Then Monsieur Roger pulledfrom his pocket a coin, and with the aid of the scissors cut a round bitof paper, a little smaller than the coin. That done, he placed thecircular bit of paper flat upon the coin, in such a manner that it didnot overlap, and asked Miss Miette to take the coin between her thumband her finger.
"Now," said he, "let it all fall."
Miette opened her fingers, and the coin upon which he had placed the bitof paper fell. Coin and paper reached the ground at the same time.
"Why," asked Monsieur Roger, "does the paper reach the ground as soon asthe coin?"
And as Miette hesitated to answer, Monsieur Roger continued:
"Because the fall of the bit of paper was not interfered with by theresistance of the air."
"Of course," cried Miette, "it is the coin which opened the way. Thepaper was preserved by the coin from the resistance of the air."
"Exactly so," said Monsieur Roger; "and these simple experiments haveled scientists to ask if in doing away entirely with the resistance ofthe air it would not be possible to abolish the differences which may beobserved between the falling of various bodies,--for instance, the paperand the coin, a hair and a bit of lead. And they have decided that in avacuum--that is to say, when the resistance of the air is abolished--thepaper and the coin, the hair and the lead would fall with exactly thesame swiftness; all of them would traverse the same space in the sametime."
"The hair falls as fast as lead," said Miette, in a tone which seemed toimply, "I would like to see that."
Monsieur Roger understood the thought of Miette, and answered bysaying,--
"Well, I am going to show you that."
He chose a long tube of glass, closed by bits of metal, one of which hada stop-cock. He put in this tube the coin, the round bit of paper, a bitof lead, and a strand of hair from Miss Miette's head. Then he fastenedthe tube by one of its ends upon the disk of the air-pump and worked thepistons. As soon as he thought that the vacuum had been made, he closedthe stop-cock of the tube, to prevent the exterior air from entering. Hewithdrew the tube from the machine, held it vertically, then turned itbriskly upsidedown. Everybody saw that the paper, the coin, the hair,and the lead all arrived at the same time at the bottom of the tube. Theexperiment was conclusive. Then Monsieur Roger opened the stop-cock andallowed the air to enter into the tube. Again he turned the tubeupsidedown: the coin and the bit of lead arrived almost together at thebottom of the tube, but the paper, and especially the strand of hair,found much difficulty on the way and arrived at the bottom much later.
"Why, how amusing that is!" cried Miette; "as amusing as anything Iknow. I don't understand why Paul wishes to have nothing to do withphysical science."
But Miette was mistaken this time, for Paul was now very anxious tolearn more.
"Very well," said Monsieur Roger, "as all this has not wearied you, Iam, in order to end to-day, going to make another experiment which willnot be a bit tiresome, and which, without any scientific apparatus,without any air-pump, will demonstrate to you for the last time theexistence of the pressure, of the weight of the atmosphere."
Monsieur Roger stopped and looked at Miette, whose good temper he wasagain going to put to the test. Then he said,--
"I need a carafe and a hard egg; and if Miss Miette will only be kindenough to----"
This time Miette seemed still more uneasy than ever, more embarrassed,more uncomfortable; still, she fled rapidly towards the kitchen. Duringher 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, thehard-boiled egg (it was not boiled very hard, however) in the other.Monsieur Roger took the shell off the egg and placed the egg thusdeprived of its shell upon the empty carafe, somewhat after the mannerof a stopper or cork.
"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: youwill force the egg down."
"Oh, but nobody must touch it. It must not be a hand that forces itdown, 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 threwinto the empty carafe.
"In order to burn," said he, "this paper is obliged to absorb the oxygenof 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 theegg upon the carafe's neck, very much in the manner you would place aclose-fitting ground-glass stopper in the neck of a bottle, andimmediately they saw the egg lengthen, penetrate into the neck of thecarafe, and at last fall to the bottom. "There," said he, "isatmospheric pressure clearly demonstrated. When a partial vacuum hadbeen made in the carafe,--that is to say, when there was not enough airin it to counterbalance or resist the pressure of the exteriorair,--this exterior air pressed with all its weight upon the egg andforced it down in very much the same way as Miss Miette wished me to dojust 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 havingsent you on so many errands. I thought I saw that it annoyed you alittle 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," criedMonsieur Roger, much moved by this touching and kindly delicacy offeeling, and opening his arms to the pretty and obliging little child ofhis friends.