"There's just the rub," replied Charley. "It would naturally be safe,
being so hard to get to, and for that reason it wouldn't be watched as
well as more accessible regions, particularly when it is difficult to get
fire patrols. But because some one is evidently trying to burn this
particular stand of timber, it is especially necessary to guard it. Mr.
Marlin wants it watched continually, but so secretly that no one will
realize that it is being guarded. That might make the incendiary
careless--providing he comes again--and so lead to his detection. We must
do nothing to betray ourselves. We'll have to be careful not to mark this
tree in any way, so that a passer-by would guess it was used as a
watch-tower. And we shall have to be sure that we don't wear a path
leading from it to our camp."

For many minutes the boys sat in the tree, well screened from observation
by the spreading limbs, yet themselves able to see perfectly. In every
direction they searched again and again for telltale columns of smoke, but
saw nothing.

"It looks to me," remarked Charley, "as though there isn't a soul in this
region except ourselves. If that is so, it is the best possible time to do
a little exploring. Suppose we take a look at the valley above our camp.
We can cover a lot of ground between now and noon and yet get back here
for another observation during the dinner hour. We ought to be in this
watch-tower or at some other point equally good every time men would
naturally be having fires, and that means morning, noon, and night.
Between times we can explore the forest. It means some pretty stiff
hiking, but I guess we can stand it."

They drew their map and compared it with the country as it actually
appeared.