Chapter XX: A Clue From the Air

Slowly the little police-boat finished her circuit, nosing into every dark nook and spying out every black corner; but blacker than either the night or the water was the gloom in the hearts of Captain Hardy and his fellow members of the wireless patrol. With bowed head the disappointed leader turned to the commander of the boat, to tell him to return to his dock. But Captain Hardy was too loyal to his fellows, too resentful of Lieutenant Gavigan's remarks about them to indicate by word or act that he thought they had been on a wild-goose chase. So he said simply, "We were too late, Lieutenant. They have given us the slip. But none the less I thank you for your assistance."

Then he turned aside and stood peering gloomily into the dark waters, that reflected the exact shade of his own mind. Appreciating better than his youthful companions the full extent of the disaster that had befallen them, he could not, for the time being, summon up his usual fortitude or see any hopeful prospect. Now that the spies knew that they were discovered, he felt sure that they would never risk the sending of another wireless message. And a wireless message was the sole clue by which his little patrol might once more pick up the trail of the fugitives.

But Captain Hardy's disappointment was no whit keener than that of his fellows, nor his sufferings any more poignant; yet with the buoyancy of inexperienced youth, hope was not entirely crushed in the heart of any one of the young scouts. So absolute was their faith in their leader, so astonishing had been the good fortune that so far had attended their efforts, that each felt that in some way this present disaster would yet be retrieved. And with hope as a motive power, each began, in a manner true to his character, to attack the problem that confronted them, to get ready for further service. It was a splendid example of the spirit of "never say die" that their leader had drilled into them--an example that he would be quick to follow, once the shock of disappointment had passed away.

Lew, hopeless of solving the puzzle of the spies' disappearance, was thinking of how the scouts should equip themselves if they should be called upon for a land pursuit; for at following trails and taking care of himself in the open he had no superior in the wireless patrol. Roy, keen minded as a Sherlock Holmes, was turning over in his mind the problem of the spies' escape, trying to reason out what their line of action would be in the immediate future. Willie was examining a mental landscape to decide the same question. With that wonderful facility of memory he had acquired by hours of practice at Camp Brady, he now called up the maps of the neighboring waters he had been studying; and in his mind's eye he could see every point and indentation of the shore-lines, every arm of water, every inequality of the land as pictured on the contour map, and the principal roads of the region. And he was asking himself what a party of fugitives in a small boat would naturally do.

Henry, eager as always to learn more about the wireless, had ingratiated himself with the _Patrol's_ wireless man and was eagerly examining his instruments and plying him with questions. At first the operator answered with good-natured tolerance as one replies to the queries of a child. But when he saw how much Henry actually knew, and found that though he was only a boy he had already acted as operator at a government wireless station, he fell into an earnest discussion about the possibilities of wireless in police work--for in New York the police wireless was still in an experimental stage. Then he permitted Henry to clamp on the receivers and listen in.

Henry welcomed the opportunity, for in all the weeks they had been watching the Germans, the wireless patrol had hardly had an opportunity to listen to the myriad voices in the air. They had had to shut out all other sounds and tune down to the low lengths used by the Germans--and by nobody else. They had been like spectators at the opera with their ears plugged to shut out the music.

Now, as Henry eagerly listened in, he caught a sharp, whining note that vibrated powerfully in his ear. "There's the Navy Yard calling," he said, and a deep frown passed over his face, for it made him think of submarines and the failure of the wireless patrol. For a moment he tuned to a short length and listened for a spy message, as he had done so many times before.

"That's the Waldorf-Astoria talking," said Henry a moment later, and he copied down the message and shoved it over to the police operator.

Then followed press despatches--stories of land and sea, of fires and battles, of shipwrecks and the arrest of a spy. And again Henry scowled and slid his tuning-coil and briefly listened in at lower range.

Down the river ploughed the little steamer, repassing, one by one, the landmarks it had passed on its trip northward. As it steamed along and the meaning of their failure became more apparent to the young scouts, they became gloomier and gloomier. But Henry, exulting at the opportunity to handle such an outfit, almost forgot their failure, and drank in eagerly the gossip of the night. So engrossed was he, that he was startled when he heard the order to slacken speed, and heard his captain say, "Well, here we are, boys."

Reluctantly he removed the receivers. Then, as an after-thought struck him, he clamped them again to his ears, tuned his coil to a low length, and strained his ears in one last search for a forbidden voice in the dark. For a moment he sat listening vainly. Then, with unwilling fingers, he began to take the clamps from his head. But suddenly he jammed the receivers back on his ears and sat tense.

"Hurry up, Henry," called Captain Hardy. "We're waiting for you."

"Hush!" said Henry, lifting a warning hand. Then he sat rigid, bending eagerly forward. In his ear a call was sounding. It was the old familiar call of the motor station. He seized a pencil and began to write. A moment later he jumped to his feet and went rushing after his captain.

"Here!" he called, thrusting a paper into Captain Hardy's hand. "The motor-car station just sent this message."

"The motor-car station!" exclaimed Captain Hardy, in astonishment. "Then Sanders can't be aboard the motor-boat. The Chief said he had him covered so closely that he could not escape--and evidently he couldn't." A moment later Captain Hardy stood frowning, trying to puzzle out the meaning of it. "I don't see how he could have sent a message," he continued, "if he is so closely watched that he couldn't get away."

"Perhaps the message will tell us," suggested Roy.

"Right again, Roy," said Captain Hardy. "We'll hurry to the office and decipher it."

On the run they made their way to the subway station at Bowling Green. They caught a north bound train and shortly afterward swarmed up out of the subway and made a rush for the secret service offices.

With hardly more than a word of greeting they drew up at a table and laid the paper with the message before them.

"Forty," said Captain Hardy, counting the letters. "If they use the same cipher they did last time, that'll make five columns of eight letters each." Rapidly he set down the letters in the order indicated, thus:

T T E N R
H A S E Y
G Y U R A
I L O E B
N T V R O
D C Z E H
I A E V C
M X D E E

Then slowly he read off the message: "ECHO--BAY--REVERE--RENDEZVOUS--EXACTLY--AT--MIDNIGHT."

With a cry of joy Captain Hardy leaped to his feet. "We've got another chance," he said. "Sanders must be going to meet them at Revere Rendezvous--wherever that is." Then, turning to a man at the next desk, he inquired, "Where is Echo Bay?"

"At New Rochelle," said the agent. "That's where Fort Slocum is."

"Fort Slocum!" cried Captain Hardy. "This may be even more serious than it seems. Can this man be spying on the fort, too? How far is New Rochelle from here?"

"Eighteen or twenty miles."

"Can we get there by twelve o'clock?"

"Sure. Why?"

"The spies we are after are to meet at Echo Bay, Revere Rendezvous, at midnight. Are you sure that we can get there?" Then he glanced at his watch. "It's already long past ten."

The Chief was still at the office. The agent went to consult him, and came back for details. Captain Hardy stepped into the Chief's private office and made the entire situation plain. The Chief sat like a cake of ice, a thinking machine immovable and unmoved, listening to the recital.

"How many men have you here?" he asked his subordinate, the instant Captain Hardy had done talking.

"Four."

"Two of you go by automobile, two by motorboat. Divide these boys and take half with each party. Let those who go by land approach the meeting-place on foot and hide. The motorboat must come in behind the spy boat and cut off retreat. Be sure you are armed."