as a compass can mark. Now if this country was an open one with no
bogs to go around, and nothing to keep us from going straight ahead, I
shouldn't need any assistance, but could go on in a straight line all
day long. As it is, I must establish a long straight line, reaching as
far ahead as possible, and then pick out two things in the line, one
near me and one at the far end, which we can recognize again from any
point. Then we'll go on by the best route we can till we come to the
furthest object, and then I'll show you how to get the line again.
What I want you to do is to notice the 'object trees' as we'll call
them, so that we can be sure of them at any time. Notice them in
starting, and as often afterward as you can see them. The appearance
of trees varies with distance and point of view, and it is important
that we shall be sure of our object trees and make no mistake about
them."

"All right, Captain Sam," cried the boys, "pick out your object
trees."

"Well," said Sam, "the big sycamore yonder will do for one, and that
tall leaning pine away over there almost out of sight must do for the
other. That is in our line, and what we've got to do is to get to it.
It doesn't matter by how crooked a route, if we can remember the
sycamore tree again and pick it out from there."

"We'll watch 'em captain, and we won't let 'em slip away from us,"
said Sid Russell.

"Thank you, boys," replied Sam; "I shall be so busy picking our way,
that I can't watch them very well. Now then, we're ready, come on."