“Perhaps I had better not do this,” he said to Nan. “It might be that Bert went off by himself. I don’t mean that he played truant, Nan,” he said, as he heard the girl gasp. “I mean he might have met some one from your father’s office, or something like that. Those at your house—the servant or this old lady that you told me was helping you keep house—would know nothing about it, and it might worry them if we asked about Bert.”

“I’ll tell you what to do. I’ll ask Miss Skell to excuse you, and you may go home to see if Bert is there. If he isn’t, come back and let me know. Then I will do something else. You need not alarm Dinah or Mrs. Pry. I will ask you to go home to get me a certain book. Let me see, I remember Bert once brought to school a book of your father’s containing a number of fine poems for recitation. I’ll send you home to get that book. Then you won’t worry the old lady. How will that do, Nan?”

“It will be a good plan, I think,” Nan answered. “And I hope I’ll find Bert there.”

“Yes. Or at least learn whether or not he has been sent on an errand,” added the principal. “Give this note to Miss Skell.”

He hastily wrote one, and when Miss Skell read it she said to Nan:

“Get on your hat and coat and go.”

The boys and girls in the room, noting that Bert was not present and seeing Nan go out, did not know what to think. It was very mysterious.

But it was more than mysterious to Nan Bobbsey when she reached home and saw nothing of Bert. Mrs. Pry saw the girl coming up the steps and opened the door for her.

“Why, my dear, school isn’t out already, is it?” asked the old lady.

“No, I came back to get a book for Mr. Tarton,” Nan answered. “Did Bert get his arithmetic?” she inquired.