lamp opposite to the opening. The air
pressed the flame in towards the room, in all cases.

"People commonly say, that it is _drawn_ in," said his father, "but that
is not strictly correct; it is really _pressed_ in. There is no power of
attraction, in the air that is in the room, to draw in the air that is
out of doors, through the crevices; but the air that is out of doors, is
so heavy, that it presses in, and crowds the warm and light air up the
chimney.

"And now," said his father, "I cannot tell you anything more this
evening; but, if you remember this, I will give you some further
instruction another time."

"Well, sir," said Nathan, "only I wish you would tell me a little story,
as you did last evening. Have not I been still?"

His father had noticed, that he had been very still and attentive, but
did not think before, that it was in expectation of being rewarded with
a story.

"Well," said his father, "I will tell you a story, or give you a little
advice. How should you like a little advice?"

"Well, father, a little advice; just which you please."

"I advise you, then,--let me see,--what shall I advise you?--No, on the
whole, I will tell you a story. Once there was a man, and he was a
philosopher. He understood all that I have been explaining to you about
the air being light when it was hot. So he got some very thin paper, and
made a large paper bag. He cut the paper very curiously, and pasted it
together at the edges in such a way, that the bag, when it was done, was
round, like a ball; and it had a round opening at the bottom of it. In
fact, it was a large paper ball."

"How large was it?" said Nathan.

"It was so large, that, when it was swelled out full, it would have been
higher than your head."

"O, what a large ball!" said Nathan. "But what was it for?"

"Why, the man thought, as hot air is lighter than cool air, and floats
up, that perhaps, if he could fill his paper ball with hot air, it would
go up too."

"And did it?" said Nathan.

"Yes," said his father. "He filled it with hot air; and the hot air was
so light, that it rose up and carried the paper ball with it."

"How did he get the hot air into it?" said Rollo.

"Why, he held it over a little fire, with the mouth down. Then the hot
air from the fire went up into the ball, and swelled it out full."

"How high did it go?" said Nathan.

"O, it soared away," said his father, "away up into the air, very high;
until at length it go