Henry dropped to the ground and lay still for a moment. Then he crept, like an Indian, toward the sheltering thicket. Through it he advanced until he was not more than fifty feet from the motor-car. He could see with fair distinctness, but was himself completely concealed. He lay like a log, watching intently.
The driver unfastened his top and slid it backward. As he did so, his overcoat caught on the open door and he gave an exclamation of impatience. When he had laid his top back, he lowered the upper half of his wind-shield. Then, standing on the running-board, he tugged at the top of his wind-shield standard. Up came a sliding inner tube. In a flash the entire mystery stood revealed to Henry. The wind-shield standard contained a collapsible mast, like the telescoping cane he held in his hand. Doubtless an aerial was now fastened to the mast. Somewhere within the car was a wireless outfit. Instead of having many secret stations, the Germans had this one portable station.
Up came a sliding inner tube
"How clever!" thought Henry. "And how well they deceived us."
The spy proceeded to run up his mast. It must have reached twenty feet into the air. And the aerial was dangling from it, too. Evidently the spy had fastened that on before raising the mast. Fifty feet distant stood a tree. The spy took something from the baggage container and walked over to the tree, where, Henry judged by the sound, he was fastening a hook. Then the spy carried over the other end of his aerial and fastened it to the hook. In the darkness Henry could see nothing of the details of this outfit, but he realized that the spy now had an aerial at least fifty feet long and well above the ground. For short distance communication it would answer perfectly.
The spy returned to his car and got into the seat beside the driver's. Henry wormed his way forward as far as he dared, hardly breathing, fascinated by what he beheld. For now he could see plainly. The spy had turned on a tiny light on his dashboard. Cautiously Henry rose to his feet, keeping behind a thick bush, and peered over the side of the car. The spy took a key from his pocket and unfastened a hidden lock. The entire cowl board turned down, revealing a compact but powerful wireless outfit. The aerial wire evidently was strung up within the collapsing mast.
From within the cowl the spy drew forth a curious metal disc, not unlike a spider-web, and like nothing Henry had ever seen. He did not know what it was. He hardly breathed as he stood watching. Then the spy took a dollar from his pocket, examined the milled edge until he found a scratch, fitted the curious disc over the dollar, and turning the coin in his hand, slowly began to make letters on a slip of paper on the inverted dash. When he had finished writing, he fastened the disc back in the cowl, dropped the dollar in his overcoat pocket, and began to send the message he had deciphered from the dollar.
Henry leaned forward. He had no need of his own receiving instrument to catch the letters. And he could not have used it if he had needed it. But it was not important that he should catch the message. The powerful sparks that were leaping across the spy's spark-gap told him that a battery of considerable force was being used, and he knew that Lew would catch that message away back on Staten Island. Lew had caught the preceding message from Long Island, and it had been sent from a distance fully as great as this. With distinctness the letters came to Henry's ears and he realized that the man before him was an expert operator. But the letters he heard made no sense. They would have to be deciphered before the message could be understood.