"Of course. I didn't think of that, that's all. But if we come back we can get the note back before anyone sees it. Is that what you mean, Paul?"
"Yes. Now study that map very carefully. I think we can remember where the cross marks are, all right."
"I can remember this one," said Arthur. "It's exactly on the spot where that new house was built last summer, near the Ourthe. Don't you remember? We stopped and got some milk there, and we wondered how a farmer could build such a solid looking house when he didn't seem to have much money or much of anything else. A stupid fellow, he was. He scarcely knew enough to give us the milk we wanted."
"Yes, I remember now," said Paul, looking at the map again. He was thinking hard, trying to fathom the connection between what they both remembered of that house and the strange, significant cross on the map. There was a connection; the cross did have some significance. Of so much he was sure. But for the life of him that was all he could guess. It was a perplexing problem.
"Come on," he said, at last, impatiently. "I may be very stupid, but I don't understand. The only way we'll find out will be by going there."
"All right," agreed Arthur, grinning. "I'm wiser than you for once, Paul. I haven't even tried to find out. I know I can't guess, so I'm not wasting time trying to. I think we'll be lucky if we find out when we do get there."
"So do I, come to think of it," said Paul. Somehow he felt better; before he had been inclined to blame himself for being stupid. "After all, you know, Arthur, even if they didn't expect anyone like us to get hold of these maps and sketches, that doesn't mean that they would make everything on them so plain that you could guess it at first sight. That sort of mark is awfully easy to understand when you have the key, but it's as bad as a cipher if you haven't."
It was quite dark, of course, when they finally set out. Though it was Saturday night few people were about, and the locality was a lonely one. Then, too, all of those who could had gone into the town. It was there that news of what was going on in the great world outside would first be had; it was there that the country people could count upon getting the first hint of the intelligence that was to have so frightful a meaning for them.
The course the two scouts took carried them along the bank of the placid Ourthe, flowing peacefully, calmly along toward its confluence with the more important stream of the Meuse at Liege. Behind them one strange thing proved that all was not quite normal. From Fort Boncelles a searchlight began to play. They had seen that light before, but only when it was being tested or when there were manoeuvres in progress. Now it seemed to have a sinister meaning.
"I think that means that there is war," said Paul. "They are keeping the searchlight going so that they may be sure to escape a surprise."