"Are you trying to say that we put stones in our s...o...b..a.l.l.s?"

"I don't have to say it," retorted Joe. "You just said it yourself."

Too late Buck realized his mistake, and his coa.r.s.e red face grew purple as Herb and Jimmy grinned at him in maddening fashion.

"Don't you laugh at me, Jimmy Plummer!" he exclaimed, picking on Jimmy as being the least warlike of the radio boys. "I'll make you laugh out of the other side of your mouth in a minute," and he started to dash past Bob to reach his victim.

But to do so he had to pa.s.s between Bob and the bank of the lake, which just at this point was a foot or so above the water.

As he rushed past, Bob adroitly shot out a muscular arm and his elbow caught the bully fair in the side. Buck staggered, made a wild effort to regain his balance, and with a prodigious splash disappeared in the icy waters of the lake.

For a few seconds friend and enemy gazed anxiously at the spot where he had gone under, but he soon came to the surface, and, sputtering and fuming, struck out for the sh.o.r.e and dragged himself out on to dry land.

He made such a ludicrous figure that even his cronies could not forbear laughing, but he turned on them furiously and their laughter suddenly ceased. Then he turned to Bob.

"If I didn't have these wet clothes on, I'd make you pay for that right now, Bob Layton," he sputtered. "I'll make you sorry for that before you're much older."

"Why not settle it right now?" offered Bob. "Your clothes will dry soon enough, don't worry about that."

"Yes, I know you'd like nothing better than to see me get pneumonia,"

said Buck. "You wait here till I go home and get dry clothes on, and I'll come and give you the licking that you deserve."

"That's only a bluff, and you know it," said Bob contemptuously. "But if any of your friends would like to take your place, why, here I am. How about you, Lutz?"

But Carl muttered something unintelligible, and backed away. The others likewise seemed discouraged by the mischance to their leader, for they turned and followed his retreating form without another word.

"Some sports!" commented Joe.

"Game as a mouse," supplemented Herb.

"That was a swell ducking you gave Buck," chuckled Jimmy. "Just when he was going to pick on me, too. I owe you something for that, Bob."

"Pay me when you get rich and famous," laughed his friend. "You don't owe me anything, anyway. It was a pleasure to shove Buck into the lake.

I'm perfectly willing to do it again any time I get the chance."

"Oh, it's my turn next time," said Joe. "I can't let you hog all the fun, Bob."

"All right," replied his friend. "If we run into him again, I'll leave him to your tender mercies. But I don't imagine he or his friends will bother us any more to-day, so why not have lunch?"

"I was thinking the same thing," remarked Jimmy, and they forthwith set to work to prepare what Jimmy termed a "bang-up lunch."

CHAPTER XVIII

A STARTLING DISCOVERY

The cook had supplied the radio boys with a lavish hand, but their long walk and the swim had given them ravenous appet.i.tes, and by the time they finished there was little left of the lunch. Even this little was soon disposed of by the bright-eyed birds that ventured close in pursuit of the tempting bits. By sitting as still as statues the boys succeeded in enticing the little fellows almost within arm's length, and derived no little amus.e.m.e.nt at the evident struggle between greed and caution.

But soon the last crumb was gone, and after a short rest the lads began to think of returning to camp. They did not want to go back by the same road over which they had come, however, so decided to follow the sh.o.r.es of the lake until they should find some other path. This was, of course, a roundabout way of getting home, but they had the better part of the afternoon before them, and were in no particular hurry.

"Come on over to the north," suggested Joe. "I think there is another trail in that direction."

"Yes, and I imagine the walking is better," put in Herb.

"Say, you don't want to go too far out of the way," came hastily from Jimmy. "We've got to walk back remember."

"Forward it is!" cried Bob. "Come on, Jimmy, you've got to walk off that big lunch you stowed away."

"Gee, if I walk too far I'll be hungry again before I get home," sighed the stout youth.

"Wow! hear Jimmy complain," burst out Joe. "He hardly has one meal down than he's thinking of another."

To find another trail was not as simple a matter as it had seemed, and they must have traveled over two miles before Bob's keen eyes detected a slight break in the dry underbrush that might denote a path such as they sought. They found a dim trail leading in the general direction in which they wished to go, and set out at a brisk pace, even Jimmy being willing to hurry as visions of the loaded supper table floated before him.

Gradually the path widened out, as others ran into it, until it became a fairly well-defined woods road. It was thickly strewn with last year's soft and rotting leaves, and the boys made little sound in spite of the rapidity of their pace. Bob and Joe and Herb were striding along in a group, Jimmy having dropped behind while he fixed a refractory shoe lace, when suddenly Bob halted abruptly and held up a warning hand. The others, scenting something amiss, stopped likewise, looking inquiringly at Bob.

Silently he pointed to a spot slightly ahead of them and several paces off the road. Even as the others gazed wonderingly, Bob beckoned them to follow and slipped silently into the brush that lined the road.

On the other side stood a big tree, its trunk and branches sharply outlined against the clear sky. At the base of this tree, with his back toward them, stood a man. Now, the surprising part of it all, and that which had caused the boys to proceed so cautiously, was the fact that the man wore headphones and was evidently receiving a message of some kind. Fastened to the tree was a box, which evidently contained telephonic apparatus. At first the boys thought he must be listening at an ordinary telephone, but the fact that he had no transmitter indicated that he was listening in on a radio receiving set.

The boys had hardly reached their place of concealment when the man turned sharply about, darting furtive glances here and there, evidently in search of possible intruders. The boys crouched lower behind the bushes and prayed fervently that Jimmy would not arrive before the man had gone. The fellow was of fair size, with a deeply tanned face, and wore a moustache. Fortunately, after they had been watching him a few minutes, he removed the earphones, placed them in the box, and, after locking it, started into the woods, following a dimly marked footpath.

It was well that he left when he did, for not two minutes later Jimmy came puffing along, looking anxiously for the others. He stopped in amazement when he saw his friends emerge from the bushes, and was about to raise his voice in vehement questionings when Bob leaped at him and clapped a hand over his mouth.

"Be quiet!" he hissed into his ear. "There's some funny work going on here, and we want to find out what it is."

Thus admonished, Jimmy was released, and in low tones the others told him of what they had seen and showed him the box fastened to the tree.

While they were about it, they made a hasty search for the antenna, and found it strung close to the trunk of the tree, extending from the top almost to the roots. After this discovery they hurried after the man with the moustache, fearful lest they should lose his trail.

It was no easy matter to follow the dimly marked path, for it pa.s.sed at times over stony ground and big boulders, where often it took much searching here and there before they picked up its continuation.

"We may be taking all this trouble for nothing," said Bob, after one of these searches. "Maybe he's just a lumberman receiving instruction by wireless from his employers. Big business firms are using radio more and more for such purposes."

"I didn't like the way he kept looking about him, as though he had something to conceal," objected Joe. "It can't do any harm to see where he goes, anyway. We may find out something important."

"His hands weren't those of a lumberman," observed Herb. "Those hands never saw rough work nor, judging from the man's face and manner, honest work. Come on, fellows."

Accordingly the boys followed the difficult trail with untiring patience, and at last their perseverance was rewarded. The path widened out into a little clearing, and at the further side of this was a rough log cabin. The little shack had two small windows, and with infinite caution the boys approached until they could see into the nearest one.

The interior was rudely furnished with a heavy table and two crudely fashioned chairs, while in the corner furthest from them two bunks had been built, one above the other. In another corner was a compact radio transmitting set.

At the table was seated the man with the moustache, intently studying a notebook propped up before him. From this he made notes on a sheet of paper, scowling at times like one engaged in a difficult task. At length he shoved back his chair, rose to his feet, and, striding across the little shack, carefully placed the notebook under a board on a shelf.

Luckily he was so absorbed in what he was doing that he did not even glance toward the window where the radio boys were observing his every motion.

But Bob now judged that they had seen enough, and he wished to run no unnecessary risk of detection. At a signal from him they made for the underbrush at the edge of the clearing, where they could command a view of the door, and waited to see if the mysterious stranger would emerge.