For what seemed a long time Mr. Tetlow stood looking over the room full of pupils. One could have heard a pin drop, so quiet was it. The hard breathing of the boys and girls could be heard. From over in a corner where Danny Rugg sat, came a sound of whispering.

"Quiet!" commanded the principal sharply. "There must be no talking. I will wait one minute more for the guilty ones to acknowledge that they rolled the big snowball on the steps. Then, if they do not speak, I shall have something else to say."

The minute ticked slowly off on the big clock. No one spoke. Bert glanced from side to side as he sat in his seat, wondering what would come next. Many others had the same thought.

"I see no one wishes to take advantage of my offer," said Mr. Tetlow slowly. "Very well. You may all go to your class-rooms, with the exception of Bert Bobbsey. I wish to see him in my office at once. Do you hear, Bert?"

There was a gasp of astonishment, and all eyes were turned on Bert. He grew red in the face, and then pale. He could see Nan looking at him curiously, as did other girls. Bert was glad Flossie and Freddie were not in the room, for the kindergarten children did not assemble for morning exercises with the larger boys and girls. Flossie and Freddie might have been frightened at the solemn talk.

For a moment Bert could hardly believe what he had heard. He was wanted in Mr. Tetlow's office! It did not seem possible. And there was but one explanation of it. It must be in connection with the big snowball. And Bert knew he had had no hand in putting it on the school steps.

There was a buzz of talk, many whisperings, and some one spoke aloud. It sounded like Danny Rugg, but poor Bert was so confused at his own plight that he could not be sure.

"Silence!" commanded Mr. Tetlow, as the boys and girls marched to their various rooms. "Bert, you will wait for me in my office," he added. Poor Bert looked all around. He met many glances that were kind, and others, from Danny Rugg's friends, that were not. Nan waved her hand at her brother as she passed him, and Bert smiled at her. He made up his mind to be brave. Bert went to the principal's office, and sat in a chair. There was another boy there, who looked at Bert in a questioning manner.

"Are you here to get some writing paper, Bert?" asked the other boy.
"Miss Kennedy sent me for some."

"No," answered Bert. "I only wish I was. I guess Mr. Tetlow thinks I had something to do with the big snowball."

"Did you?"

"I did not!" exclaimed Bert quickly.

The principal entered a little later, gave to the other boy the package of writing paper Miss Kennedy had sent for, and then sat down beside Bert.

"I am sorry to have to do this, Bert," he said, "but this is a serious matter and I must treat it seriously. Now again, I ask if you have anything to say to me? Perhaps you were too worried to stand up before the whole school."

"No, sir," answered Bert, "I don't know that I have anything to say, if you mean about the big snowball."

"Then you deny that you had anything to do with it?"

"Yes, sir. I never helped roll it on the steps."

"Do you know who did?"

"No, sir. I haven't the least idea."

"And you were not anywhere near it?"

"No, sir."

"Ahem! Let me ask you, have you a knife, Bert?"

Without thinking Bert's hand went to his pocket, and then, as he recalled something, his face turned red, and he said:

"I have one, but I haven't got it now."

"Is this it?" asked Mr. Tetlow, suddenly holding out one.

Bert did not need to give more than a single glance at it to know that it was his knife. It had his name on the handle and had been given him by his father at Christmas.

"Yes, that's mine," he said slowly.

"So I thought. And do you know where it was found, Bert?"

"No, Mr. Tetlow, I haven't any idea."

"Suppose I told you the janitor picked it up on the steps almost under the big snowball? If I tell you that what have you to say?"

"Well, Mr. Tetlow, I'll have to say that I don't know anything about it.
I didn't drop my knife there, I'm sure."

"Then someone else must have done it. Be careful now, Bert. I don't want to be hasty, but it looks to me very much as though you were one of the boys who had played this trick—a trick that has made considerable trouble. I am sure there must have been others concerned with you, and I am almost positive that you had a hand in it.

"Now I am not going to ask you to tell tales against your companions. I don't believe in that sort of thing. But I am very sorry that you did not admit at first that you had a share in rolling the big ball. Very sorry, Bert."

"But, Mr. Tetlow, I didn't do it!" cried poor Bert, the tears coming into his eyes. "I don't know how my knife got there, but I do know I didn't help roll that ball. Please believe me; won't you?"

For a moment the principal was silent. Then he said slowly:

"Bert, I would very much like to believe you, for I have always found you a good, manly and upright boy. But the evidence is strong against you I am sorry to say. And this trick was one I can not easily overlook. Rolling the snowball on the steps was bad enough, but when water was poured over it, to freeze, and become ice, making it so much harder to clean off, it made matters so much worse.

"Besides making a lot of work for the janitor, there was danger that some of the teachers might slip on the icy path and be injured. If your knife had only been found lying on top of the ice I might think you had come up merely to look at the big ball, and had dropped your property there. But the knife was found frozen fast, showing that it must have been dropped during the time the water was poured on the steps. So you see whoever left it there must have been on hand when the trick was played."

"That may be true, Mr. Tetlow!" cried Bert, "but I did not leave my knife there. I remember now—I can explain it! I couldn't think, at first, but I see it now."

"Very well," said Mr. Tetlow quietly, "I'll hear what you have to say,
Bert."