"I have no doubt we shall find the secret station in that grove," said Captain Hardy. "I see several tall trees sticking up above the others that might conceal aerials. I doubt if any one is there now, but some one might be. So we shall have to approach carefully and in such a way that we can capture any one who might be within the grove. Suppose we advance on it from all four sides, as we did on the willow copse at the Elk City reservoir. Then if any one is within the grove we shall see him."
The leader gave each boy his orders and the advance began. Henry was to circle and enter the woods from the rear. Roy was to approach from one side and Willie from the other. Lew was to go in at the front. Captain Hardy and the secret service man were to station themselves outside the wood so that they could see every point of its exterior and detect any one leaving it. Each glided away toward his post.
At a given signal from Captain Hardy, the boys began to work their way silently from their posts into the grove. This was small in extent and such precautions seemed almost unnecessary. But after their desperate experience with the dynamiters, the members of the wireless patrol were taking no chances. They knew full well that discretion is the better part of valor. And they knew, in addition, that the success of their search might depend upon the caution with which they proceeded. So they went forward, when the captain's signal rang out, like so many Indians on the war-path, stalking a hated enemy.
Indeed they were almost as invisible as Indians. Each had circled skilfully to his post. And now each crept forward silently, slipping from rock to bush, taking advantage of the slightest cover, and advancing so stealthily through the tall grass that even the two men on watch outside the grove could hardly tell where the scouts were moving. And any one inside the grove could not have detected them at all.
The four scouts reached the four sides of the grove almost simultaneously. Each of the four crept round the trunk of a big tree and squatted down with the trunk at his back, to look and to listen. From side to side their eyes roved, examining every tree and stump in sight. But they saw nothing on the ground or in the branches overhead to alarm them. There was no indication of human presence other than their own; and Willie was certain that the wood was deserted, for several small flocks of birds flew up in alarm as he penetrated the grove. Had other men been within the wood, he knew the birds would long ago have been frightened away.
Slowly the four scouts worked their way toward the centre of the grove, gliding round the trunks of trees and stopping every few feet to look and listen. But they heard nothing, saw nothing, to indicate that any man was within the grove. Each one, as he advanced, scouted to right and left of his line of march, so that when the four met in the centre of the wood, they had covered every rod of ground within the grove. And they had found nobody.
What was more, they had seen no signs of a wireless outfit. But, in view of their experience in searching for the dynamiters' hidden wireless, this was not surprising. None of the scouts had expected to find the secret plant without a thorough search. As soon as Captain Hardy and the secret service man joined them, a systematic search of the wood was begun.
There could not have been more than two hundred trees in the little grove. Satisfied that the place contained no enemy agents, Captain Hardy took his company to one end of the ground and began a careful examination of each tree. The six searchers strung out in a line across the grove, testing each tree as they advanced. They scanned the trunks and thumped them with clubs to make sure that they were not hollow. They peered at them from all sides, looking for holes and hollow limbs. With sticks they scratched away the leaves from about the bases of the trees, turning up the soil for several inches and testing it for hidden wires. All the trees seemed sound. No hollow limbs were discovered. No suspicious marks were found in the earth about the tree trunks. The tall trees noted by Captain Hardy seemed never to have been touched by man. From tree to tree the search proceeded until every tree in the grove had been tested and the scouts were on the far edge of the wood. But no hidden wire, no secret instruments, no skilfully concealed aerials were found.
Blankly the searchers looked at one another. "It must be here," said Henry. "I am absolutely certain that the motor-car came from this direction and was about this distance from where I stood. And the signals were so loud and clear that I'm just sure they were sent from some spot close by."
"Let us look for wheel tracks," suggested Captain Hardy. "If we can find where the car stopped, we shall know that the message was sent from some point near by. Search along the sides of the grove first."