"How high?" said Rollo.
"Why, between thirty and forty miles. But it grows thinner and thinner towards the top; so it is not as heavy, by any means, as a column of air would be, thirty miles high, and as dense all the way up as it is here."
"What makes it grow thinner and thinner towards the top?" said Rollo.
"Because," said his father, "that which is near the top, has not as much load of air above it, to press it down."
"And that which is at the top," said Rollo, "has none above it, to press it down."
"No," replied his father.
"And how thin is it there?"
"Nobody knows," said his father.
"What, nobody at all?" said Nathan.
"No, I believe not; at least I do not; and I don't know that any body does."