Just then three bells struck in the tower and at the second stroke the nine-thirty gun boomed out its welcome "Release."
As the sound died away Mrs. Harold walked over to the big window calling to the girls to join her.
"Stand here a moment," she said, then going over to the electric switch turned off all the lights.
"Why? What?" cried all the girls excepting Peggy and Polly.
"Look at the windows on the third deck of Bancroft, southwest corner," she said, unhooking a drop light from above her desk and crossing the room to the puzzled girls. "Those are Durand's and Bert's rooms. Next to them are Gordon's and Doug's. Watch closely."
Presently from two of the windows lights were flashed three times in rapid succession. Then absolute darkness.
Instantly Mrs. Harold turned the reflector of her drop light toward the academy in such a way that the light would be cast out across the night, then by turning the key on and off quickly she flashed its rays three times, paused a moment, then repeated the signal.
Instantly from the rooms mentioned came the answering flashes, which after a brief interval were repeated, Mrs. Harold again giving her reply.
"Oh, who does it? What is it for? What do they mean?" asked her visitors.
"Just our usual good-night message to each other. My boys are all dear to me, but Durand and Gordon peculiarly so. Those rooms are theirs. Shall I tell you the message the flashes carry? It is just a little honor code. I want the boys to stand well this term, but, like most boys they are always ready for skylarking, and the work from seven-thirty to nine-thirty is easily side-tracked. So we have agreed to exchange a message at gunfire if 'all is well.' If they have been boning tomorrow's work my flash light is answered; if not—well, I see no answering flash."