"If I hear anyone, Pete, or see anything wrong," said Jack, "I'll give the Patrol call—the cry of a crow."
"Sure! I'll understand, if I hear it, and I'll give the same call if I'm the one that sees something."
"Right! If we hear that call the one who hears it will stop patrolling at once and go for the sound."
"They can't see us if we keep in the shadow, can they, Jack?"
"I don't believe so, Pete. It is a pretty heavy shadow, and anyone coming over the wall is likely to have his eyes more or less dazzled by the arc lights on the other side."
"Don't call unless you have to, Pete. Remember that they're not fools, these fellows, and they're apt to know that such a call means danger, even if they don't know who's here. We don't want just to scare them off—they might come back if we did that. We want to catch the ring-leaders."
They started from the railroad spur, so they would meet there each time as they completed a round of the walls, since that was where they felt the enemy was most likely to appear.
"Sleepy, Pete?" asked Jack, when they had been at it nearly an hour.
"I would be, I think, if I wasn't walking around, Jack. That's fine, though. It helps to keep me awake."
"Same here! I've heard of being so tired that you can go to sleep standing up, or even when you're walking about, but it doesn't seem possible to me."