“What are you going to do?” asked Nat.

“Here are two notes,” said Jack, holding aloft two envelopes.

“We’ll take your word for it,” remarked Bob Movel.

“One is addressed to Professor Garlach,” went on Jack, “and in it he is advised that if he proceeds in the proper manner he can obtain information of a certain incident in history, not generally known, but in which is related how Frederic II, with a small squad of Germans, put a whole army of French to flight. It is even more wonderful than the incident which Professor Socrat related to his class, and if he speaks loudly enough in the classroom, Professor Socrat can’t help but hear it.”

“What are you going to do with the note?” asked Fred.

“Send it to Garlach.”

“And then?”

“Ah, yes—then,” said Jack. “Well, what will happen next will surprise some folks, I think. The information which Garlach will be sure to want to obtain can only be had by going to a certain hollow tree, on the shore of the lake, and he must go there just at midnight.”

“Well?” asked Dick Balmore as Jack paused, while the silence in the room was broken by Bony’s performance on his finger battery.

“Well,” repeated Jack, “what happens then will be continued in our next, as the novelists say. Now come on and help me fix it up,” and he motioned for his chums to draw more closely around the table, while he imparted something to them in guarded whispers.