“No, I won’t go in,” Freddie said.

Having swallowed the apple, the elephant held out his trunk toward the Bobbseys again.  He was asking for “more,” as plainly as though he had spoken.

“No more!” called the keeper, and this the elephant seemed to understand, for he lowered his trunk, and backed into his corner, throwing hay dust over his back as he did in the Summer to keep the flies from tickling him.

“Well, I guess we’ve seen enough of elephants for one day,” said Mrs. Bobbsey.  “I thought I should faint when I saw Flossie go into that cage.  I wish I could get a cup of tea.”

“We’ll go and have lunch,” said Mr. Bobbsey.  “It’s about noon, I think.”

They went to a restaurant near a great round stone, which was perched on the top of a big ledge of rock, and when Freddie wanted to know what it was his father told him.

“That’s a rocking stone,” said Mr. Bobbsey.  “It stands there on a sort of little knob, and it is so nicely balanced that a man, or two or three boys, can easily push it and rock it to and fro.”

“Do you mean one man can move that big rock?” asked Bert.

“Yes, he can make it rock, but he can not make it move off the rock on which it rests.  Come and try.”

Bert and his father pushed their backs against the stone, and, surely enough, they could make it rock an inch or two back and forth.  Freddie helped, or at least he thought he did, which is the same thing.  But the stone really did rock, and the children thought it was quite a wonderful thing.  Sometimes your heavy piano, if it stands on an uneven place in the floor, may be rocked back and forth a little.  That’s the way it was with the rocking stone.  The restaurant where the Bobbseys ate was named “Rocking Stone,” because it was within sight of the queer rock.

I have not time to tell you all that the Bobbsey twins saw and did in Bronx Park that day.  But they had a fine time, and Flossie and Freddie, at least, wanted to come back the next day.

“There’re lots of things that we didn’t see,” remarked Flossie.

“Yes.  And I want to rock that big stone again,” added Freddie.  “Why, it rocked back and forth just as easy as a cradle!”

“Oh, Freddie Bobbsey!  The idea!  To make out that big rock was like a cradle!” cried Flossie.

“I didn’t say it was like a cradle.  I said it wobbled just like a cradle,” replied Freddie.  “Daddy, can we go back again to-morrow?”

“I planned to take you to the Natural History Museum to-morrow,” said Mr. Bobbsey.  “There you can see all sorts of stuffed animals—­walruses almost as big as a small house, a model of a whale and many other queer things.”

“Oh, do let’s go!” begged Bert.

“We will,” promised Mr. Bobbsey, but when the next day came the plan of the Bobbseys had to be changed.

In Mr. Bobbsey’s mail that morning was a letter from his bookkeeper at the lumberyard, which, when Mr. Bobbsey had read it, made him thoughtful.