whispered Harry. "We've got to find out just how often he passes
that spot. We want to know if the intervals are regular, too, so
that we can calculate just when he'll be there."

Three times the man came and went, while they waited, timing him.
And Harry found that he passed the spot at which they had entered
every fifteen minutes. That was not exact for there was a
variation of a minute or so, but it seemed pretty certain that he
would pass between thirteen and seventeen minutes after the hour,
and so on.

"So we'll know when it's safe to make a dash to get out," said
Harry. "The first thing a general does, you know, is to secure
his retreat. He doesn't expect to be beaten, but he wants to know
what he can live to fight another day if he is."

"We've got to retreat, haven't we?" asked Dick. "It wouldn't do
us any good to stay here."

"That's so. But we've got to advance first. Now to get near that
house, and see what we can find Look out for those traps and
things our friend warned us of. It looks like just the place for
them. And keep to cover!"

They wormed their way forward, often crawling along. Both knew a
good deal about traps and how they are set, and their common sense
enabled them to see the most likely places for them. They kept to
open ground, avoiding shrubbery and what looked like windfalls of
branches. Before they came into full view of the house they had
about a quarter of a mile to go. And it was an exciting journey.