[Ill.u.s.tration]

[Ill.u.s.tration]

CHAPTER XI.

THE SMOKE WHICH FALLS.

In the evening, after dinner, Monsieur Roger, to whom Paul recalled his promise, asked Miette to go and find him a pebble in the pathway before the chateau. When he had the bit of stone in his hand, Monsieur Roger let it fall from the height of about three feet.

"As you have just heard and seen," said he, addressing Paul, "this stone in falling from a small height produces only a feeble shock, but if it falls from the height of the house upon the flagstones of the pavement, the shock would be violent enough to break it."

Monsieur Roger interrupted himself, and put this question to Paul:

"Possibly you may have asked yourself why this stone should fall. Why do bodies fall?"

"Goodness knows," said the small voice of Miss Miette in the midst of the silence that followed.

"Miette," said Madame Dalize, "be serious, and don't answer for others."

"But, mamma, I am sure that Paul would have answered the same as I did:--would you not, Paul?"

Paul bent his head slightly as a sign that Miette was not mistaken.

"Well," continued Monsieur Roger, "another one before you did ask himself this question. It was a young man of twenty-three years, named Newton. He found himself one fine evening in a garden, sitting under an apple-tree, when an apple fell at his feet. This common fact, whose cause had never awakened the attention of anybody, filled all his thoughts; and, as the moon was shining in the heavens, Newton asked himself why the moon did not fall like the apple."

"That is true," said Miette; "why does not the moon fall?"

"Listen, and you will hear," said Monsieur Dalize.

Monsieur Roger continued:

"By much reflection, by hard work and calculation, Newton made an admirable discovery,--that of universal attraction. Yes, he discovered that all bodies, different though they may be, attract each other: they draw towards each other; the bodies which occupy the celestial s.p.a.ces,--planets and suns,--as well as the bodies which are found upon our earth. The force which attracts bodies towards the earth, which made this stone fall, as Newton's apple fell, has received the name of weight. Weight, therefore, is the attraction of the earth for articles which are on its surface. Why does this table, around which we find ourselves, remain in the same place? Why does it not slide or fly away?

Simply because it is retained by the attraction of the earth. I have told you that all bodies attract each other. It is therefore quite true that in the same way as the earth attracts the table, so does the table attract the earth."

"Like a loadstone," said Albert Dalize.

"Well, you may compare the earth in this instance to a loadstone. The loadstone draws the iron, and iron draws the loadstone, exactly as the earth and the table draw each other; but you can understand that the earth attracts the table with far more force than the table attracts the earth."

"Yes," said Miette; "because the earth is bigger than the table."

"Exactly so. It has been discovered that bodies attract each other in proportion to their size,--that is to say, the quant.i.ty of matter that they contain. On the other hand, the farther bodies are from each other the less they attract each other. I should translate in this fashion the scientific formula which tells us that bodies attract each other in an inverse ratio to the square of the distance. I would remind you that the square of a number is the product obtained by multiplying that number by itself. So all bodies are subject to that force which we call weight; all substances, all matter abandoned to itself, falls to the earth."

[Ill.u.s.tration]

Just here Miss Miette shifted uneasily on her chair, wishing to make an observation, but not daring.

"Come, Miss Miette," said Monsieur Roger, who saw this manoeuvre, "you have something to tell us. Your little tongue is itching to say something. Well, speak; we should all like to hear you."

"Monsieur Roger," said Miette, "is not smoke a substance?"

"Certainly; the word substance signifies something that exists. Smoke exists. Therefore it is a substance."

"Then," replied Miette, with an air of contentment with herself, "as smoke is a substance, there is one substance which does not fall to the earth. Indeed, it does just the opposite."

"Ah! Miss Miette wants to catch me," said Monsieur Roger.

Miette made a gesture of modest denial, but at heart she was very proud of the effect which she had produced, for every one looked at her with interest.

"To the smoke of which you speak," continued Monsieur Roger, "you might add balloons, and even clouds."

"Certainly, that is true," answered Miette, naively.

"Very well; although smoke and balloons rise in the air instead of falling, although clouds remain suspended above our heads, smoke and balloons and clouds are none the less bodies with weight. What prevents their fall is the fact that they find themselves in the midst of the air, which is heavier than they are. Take away the air and they would fall."

"Take away the air?" cried Miette, with an air of doubt, thinking that she was facing an impossibility.

"Yes, take away the air," continued Monsieur Roger; "for that can be done. There even exists for this purpose a machine, which is called an air-pump. You place under a gla.s.s globe a lighted candle. Then you make a vacuum,--that is to say, by the aid of the air-pump you exhaust the air in the globe; soon the candle is extinguished for want of air, but the wick of the candle continues for some instants to produce smoke.

Now, you think, I suppose, that that smoke rises in the globe?"

"Certainly," said Miette.

"No, no, not at all; it falls."

"Ah! I should like to see that!" cried Miette.

"And, in order to give you the pleasure of seeing this, I suppose you would like an air-pump?"

"Well, papa will buy me one.--Say, papa, won't you do it, so we may see the smoke fall?"

"No, indeed!" said Monsieur Dalize; "how can we introduce here instruments of physical science during vacation? What would Paul say?"

"Paul would say nothing. I am sure that he is just as anxious as I am to see smoke fall.--Are you not, Paul?"

And Paul Solange, already half-conquered, made a sign from the corner of his eye to his little friend that her demand was not at all entirely disagreeable to him.

[Ill.u.s.tration]

[Ill.u.s.tration]

CHAPTER XII.

AT THE CENTRE OF THE EARTH.