These forts were not immediately in the town; they were about five miles, on an average, from the old citadel, long since disused as a place for actual fighting. The connections between the various forts, intended, as both boys knew, for the greater facility of their defence by means of troops fighting more or less independently, were carefully traced on another map, in which the contour of the land and the natural shelter were shown. And on this map, at certain spots, there were strange marks—well beyond the perimeter of the forts themselves, that is, outside the line that might be drawn around Liege and passing through each of the forts.
"Look at those crosses," said Paul. "What do you suppose they mean, Arthur?"
"I don't know," said Arthur, frowning. "But we can find out, you know."
"You mean by going to one or two of these places? They're some distance off."
"But we ought to find out—don't you think so?"
"Yes, you're right, of course. We can find them easily enough."
"Yes. All we've got to do is to take the map along with us. Then when we get near we can make sure by looking at it."
"We could do that, but I think we won't, Arthur. Suppose we ran into the man it belongs to again? We might not get away from him another time, and I think it would be just as well to leave these maps here. We can hide them, and then write a note and leave it where it will be found in the morning, telling them where we hid the maps."
"What's the use of hiding them if we tell some one where they are, Paul?"
"Can't you see? Suppose something happens to us, so that we can't get back? We'd want the maps to be found and taken to the commander of the forts, wouldn't we?"