“No, you had better stay with mother,” her father told her.  “But I will take Bert along.  He can take a message for me in case I have to send one.  Come along!” he called to Nan’s brother.

“All right, Daddy,” answered Bert.

Up the big stone stairs went Daddy Bobbsey and Bert.  Mrs. Bobbsey, with a worried look on her face, remained in the big rotunda with Nan and Freddie.  The two children were worried too.

“Do you s’pose Flossie is hurt?” asked Nan.

“Oh, no, I don’t believe so,” and Mrs. Bobbsey tried to speak easily.  “She has just gone into some room, or down some long hall, and lost her way, I think.  You see there are so many rooms and halls in this building that it would be easy for even daddy or me to be lost.  But your father will soon find Flossie and bring her back to us.”

“But if they don’t find her, Mamma?”

“Oh, they’ll be sure to do that, Nan.  There is nobody around this building who would hurt our little Flossie.”

“What an awful big building it is,” remarked Nan.  “And just think of the thousands and thousands of books!  Why, I didn’t know there were so many books in the whole world!  Mamma, do you suppose any of the people down here read all these books?”

“Hardly, Nan.  They wouldn’t have time enough to do that.”

And now we shall see what happens to Mr. Bobbsey and Bert.  Flossie’s father decided to try upstairs first, as Freddie seemed to think that was the way his little sister had gone.

“Of course, he isn’t very sure about it,” said Mr. Bobbsey to Bert; “but we may as well start one way as the other.  If she isn’t upstairs she must be down.  Now we’ll look around and ask questions.”

They did this, inquiring of every one they met whether a little blue-eyed and flaxen-haired child had been seen wandering about.  Some whom Mr. Bobbsey questioned were visitors, like himself, and others were men who worked in the big library.  But, for a time, one and all gave the same answer; they had not seen Flossie.

Along the halls and into the different rooms went Mr. Bobbsey and Bert.  But no Flossie could they find until, at last, they approached a very large room where a man with very white hair sat at a desk.  The door of this room was open, and there were many books in cases around the walls.

“Excuse me,” said Mr. Bobbsey to the elderly gentleman who looked up with a smile as Flossie’s father and Bert entered the room.  “Excuse me for disturbing you; but have you seen anything of a little girl—­”

“Did she have blue eyes?” asked the old man.

“Yes!” eagerly answered Mr. Bobbsey.

“And did she have light hair?”

“Oh, yes!  Have you seen her?”

Softly the man arose from his desk and tiptoed over to a folding screen.  He moved this to one side, and there, on a leather couch and covered by an office coat, was Flossie Bobbsey, fast asleep.