Page: 81

This is a scale.

A scale is an instrument for measuring weight.

Which man's weight is greater.

They are on the scale.

The weight of the thin man is 100 pounds.

The weight of the fat man is 200 pounds.

Clocks are instruments for measuring time.

This is a watch.

Watches and clocks are instruments for measuring time.

This is an instrument for measuring heat.

A yard measure is an instrument for measuring distance.

Inches,feet,yards,metres,and miles are measures of distance.

Page: 82

All bodies have an attraction for one another.

If the bodies are great the attraction between them is great.

If the bodies are small the attraction is small.

If the bodies go farther from one another the attraction gets smaller.

Here is a light.

Here is a square.

It sends out light in every direction.

I put the square at different distances from the light.

At distance 1,it gets all the light which is going out between the lines.

At distance 2, it gets one-fourth of the light.

At distance 5, it gets one twenty-fifth.

It is the same with the attraction between bodies.

Page: 83

What keeps the moon up in the sky?

Why does not the moon come down?

The moon is a great body.

Its weight is great.

The earth is a great body

Its weight is eighty-one times the weight of the moon.

Two times three is six.

The moon and the earth are not very far from one another.

The distance between them is about two hundred and thirty-nine thousand miles.

Because they are great bodies and near one another, the attraction between the moon and the earth is very great.

Why does the moon not come down to the earth?

That is a question.

Page: 84

The answer is: because it is going round the earth.

This is a cord in my hand.

The cord has a weight at its end.

The weight is hanging down on the cord which is in my hand.

I make the weight go round on the cord.

I keep the end of the cord in my hand.

Now I let the end of the cord in my hand go.

The weight goes off in a straight line.

It takes the cord with it.

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The pull of the cord in my hand kept the weight from going off in a straight line.

The attraction between the earth and the moon keeps the moon from going off in a straight line.

The moon goes round and round the earth...month after month.

It does not get farther from the earth or near to the earth.

It keeps about the same distance from the earth.

Page: 86

Here is Sir Isaac Newton, the great man of science.

Newton had a great mind.

He is under an apple tree.

It is the year 1666.

Those are apples which are over his head.

The seat has three legs.

Here is an apple which was over his head.

The apple was on a branch of the tree.

The apple came off the branch.

It came down.

It came down on Newton's head.

Page: 87

That is the story.

The story may be true or may not be true.

But that is the story.

It comes from the great writer,Voltaire.

Ture?

2+2=4. That is true.

2+2=5. That is not true.

It is a false statement.

apples are fruit.

That statement is true.

Apples are animals.

That statement is false.

In this story the fall of the apple on Newton's head was the cause of the idea.

The blow which the apple gave to Newton's head gave an idea to Newton.

It made a question come into Newton's mind.

This was the question.

Have the fall of the apple and the motion of the moon the same cause?

Page: 88

Here is a ball.

It is hanging on a cord.

I will give a blow to the ball with this stick.

I gave the blow.

Now the ball is in motion.

What was the cause of the motion?

The blow of the stick was the cause of the motion.

The ball was not in motion before the blow.

It was at rest.

It was hanging on the end of the cord.

The blow was the cause of the motion.

After the blow,the ball was in motion.

The motion came from the blow.

The motion was the effect of the blow.