CHAPTER XXII
A TASK ACCOMPLISHED
Two hours later the party was grouped around Chief Flynn, who had remained in his office to learn the result of the raid. Both motor-boats had been left in charge of the New Rochelle road-house keeper, and the entire party had returned to New York in the two motor-cars—the secret service motor and Sanders' car, for Sanders had left it at the road-house and slipped away into the darkness at midnight. The clerk from Hoboken was under arrest, too. He had been taken up by the man who was watching him. Sanders had eluded his shadow by leaving his car late in the afternoon, at a garage, ostensibly to have it washed, and by later leaving his house surreptitiously in the dark. He had not been able to reach the Balaklavan rendezvous in time to join his companions. But they had a wireless equipment aboard their boat and he had made a later appointment with them. And, even as Captain Hardy had suspected, he had been nosing around Fort Slocum in the darkness.
But this was all the secret service ever learned as to the operations of this gang of wireless spies. The prisoners refused to name those higher up, and the Chief could only guess whose might be the master minds behind the plot.
As for the various wireless agents who were relaying the spy messages to Mexico, several were caught by decoy messages and shared the fate of Sanders and the others.
Even the mystery of the sudden flight of Sanders and his crew was cleared up. Following the Chief's orders, his men on the border had taken the three silver coins away from the Mexican. And, sure enough, the coins contained messages. One was the message from New York concerning the sailing of transports. The other messages were about army secrets, and it is not yet known where they came from or how they got into the hands of the Mexican.
The latter protested violently when asked for his silver dollars, and they had to be taken from him by force. The next day one of his guards discovered that the left cuff of his shirt was missing. The shirt had been intact when he was arrested. No trace of the cuff could be found anywhere. The window of the room where the Mexican was confined overlooked a public street. And it was believed by the secret service men that the spy had written a message on his cuff in some way and dropped it out of the window to a confederate. Thereupon a warning had been flashed back along the wireless line—a warning message in the new cipher that had so puzzled the lads of the wireless patrol.
"It's all clear enough now," sighed Willie, when the story had been put together, "but when you have only one piece of a jig-saw puzzle you can't make much out of it. And one piece was about all we had for a long time. I see it all now, but there's one thing I don't yet understand. Why didn't they use a more difficult cipher?"
"I suppose," explained the Chief, "that this very pursuit and capture of the spies answers that question. They knew that if the secret service picked up their messages, we could sooner or later decipher anything they sent. But even a very simple cipher might baffle one unaccustomed to such things. Always there was the danger that some one would pick up their messages. So they chose ciphers that would bother the ordinary man but that they themselves could read readily. They didn't dare use a cipher that would require a long time to unravel, because they foresaw that they might have to flee on short notice, just as it happened."
"I see," said Willie.