but water. Why do they not pour down?"
His father answered:

"I expected this would be your question. The clouds, my son, are water,
but not in a close mass, like that in a bucket or in the mill pond. You
have seen soap bubbles, and know that a great many of them may be joined
together without breaking. It is supposed by learned men, that clouds
are nothing but many thousands of bubbles, which, being lighter than
air, would, you know, float on it."

"But, father," said John, "what makes it rain?"

"That is not certainly known," replied Mr. Harvey; "but, no doubt,
lightning has much to do with it. I will show you, this evening, several
pictures about clouds and springs of water, which will help you to
understand what I have said."

"Uncle," said Samuel, "there is one more question which I would like to
ask."

"Ask it, my boy," replied Mr. Harvey.

"I have read, sir, that the water of the ocean is salt; why, then, is
not rain water salt, too?"

"Because," said Mr. Harvey, "salt cannot be changed to vapor, and it is
too heavy to be raised, in any quantity, in the air with the water.
Yet, I suppose, that a little salt is always mixed with the bubbles that
form clouds."

CHAPTER VI.

HOW THOMAS KILLED A HAWK.

This afternoon was very hot, and the boys spent it in their room,
arranging their books and pictures, and in reading. At five o'clock,
while Thomas was standing by the window, he suddenly exclaimed: "There's
a hawk!" Both the boys ran to the window, and saw a large hawk, sailing
slowly toward the barn.

"He is the one that steals our chickens," said John. "And see, he's
flying straight for the barn. Thomas, run and ask father for the gun."

Mr. Harvey kept two guns in his house; but he used them only for
shooting hawks, when they were flying about to steal the poultry. John
and Thomas had learned to use them, and sometimes spent an afternoon in
firing at a mark. But they never did so without their father's consent.

[Illustration: THE HAWK.]

Thomas soon joined the other boys, having the gun in his hand; and after
Mr. Harvey had bidden them to be careful, they followed in the direction
the hawk was flying. They kept close by the fence, so that it could not
see them. In a short time it was over the barn yard, and sailing round
and round, in order to make a sweep downwards. "Hurry, Thomas," said
John; and Thomas ran stooping along some bushes, followed by John and
Samuel, on their hands and fee