Finding the house, when they started on their motorcycles, did not prove as difficult a task as Harry had feared it might. They both remembered a number of places they had marked from the cab windows, and it was not long before they were sure they were drawing near.
"I remember that hill," said Harry. "By Jove—yes, there it is! On top of that hill, do you see? We won't go much nearer. I don't want them to see us, by any chance. All we need is to notice which way they're signalling."
They watched the house for some time before there was any sign of life. And then it was only the flashes that they saw. Since the previous day some sort of cover had been provided for the man who did the signalling.
"What do you make of it, Dick?" asked Harry eagerly, after the flashing had continued for some moments.
"It looks to me as if they were flashing toward the north and a little toward the west," said Dick, puzzled.
"That's the way it seems to me, too," agreed Harry. "That isn't what we expected, either, is it?"
"Of course we can't be sure."
"No, but it certainly looks that way. Well, we can't make sure from here, but we've got to do it somehow. I tell you what. We'll circle around and get northwest of the house. Then we ought to be able to tell a good deal better. And if we get far enough around, I don't believe they'll see us, or pay any attention to us if they do."
So they mounted their machines again, and in a few moments were speeding toward a new and better spot from which to spy on the house. But this, when they reached it, only confirmed their first guess. The signals were much more plainly visible here, and it was obvious now, as it had not been before, that the screen they had noticed had been erected as much to concentrate the flashes and make them more easily visible to a receiving station as to conceal the operator. So they turned and figured a straight line as well as they could from the spot where the flashes were made. Harry had a map with him, and on this he marked, as well as he could, the location of the house. Then he drew a line from it to the northwest.
"The next station must be on this line somewhere," he said. "We'll stick to it. There's a road, you see, that we can follow that's almost straight. And as soon as we come to a high building we ought to be able to see both flashes—the ones that are being sent from that house and the answering signals. Do you see?"