back, stop propeller motor, rudder right, rudder left, stop steering motor, light signals front, light signals rear, launch torpedoes, and so on. The idea is that of a delayed contact. The machinery is always ready, but it delays a few seconds until the right impulse is given, a purely mechanical problem. I take advantage of the delay to have the message repeated by a signal back to me. I can even change it, then. You can see for yourself that it really takes no experience to run the thing when all is going right. Gladys has done it frequently herself. All you have to do is to pay attention, and press the right key for the necessary change. It is when things go wrong that even an expert like myself—confound it—there's something wrong!"
The Z99 had suddenly swerved. Captain Shirley's brow knitted. We gathered around closer, Gladys next to her father and leaning anxiously over the transmitting apparatus.
"I wanted to turn her to port yet she goes to starboard, and signals starboard, too. There—now—she has stopped altogether. What do you think of that?"
Gladys stroked the old seafarer's hand gently, as he sat silently at the table, peering with contracted brows out into the now brilliantly moonlit night.
Shirley looked up at his daughter, and the lines on his face relaxed as though he would hide his disappointment from her eager eyes.
"Confound that light! What's the matter with it?" he exclaimed, changing the subject, and glancing up at the gas-fixture.
Kennedy had already been intently looking at the Welsbach burner overhead, which had been flickering incessantly.
"That gas company!" added the Captain, shaking his head in disgust, and showing annoyance over a trivial thing to hide deep concern over a greater, as some men do. "I shall use the electricity altogether after this contract with the company expires. I suppose you literary men, Mr. Jameson, would call that the light that failed."
There was a forced air about his attempt to be facetious that did not conceal, but rather accentuated, the undercurrent of feelings in him.
"On the contrary," broke in Kennedy, "I shouldn't be surprised to find that it is the light that succeeded."
"How do you mean?"
"I wouldn't have said anything about it if you hadn't noticed it yourself. In fact, I may be wrong. It suggests something to me, but it will need a good deal of work to verify it, and then it may not be of any significance. Is that the way the Z99 has behaved always lately?"
"Yes, but I know that she hasn't broken down of herself," Captain Shirley asserted. "It never did before, not since I perfected that new coherer. And now it always does, perhaps fifteen or twenty minutes after I start her out."
Shirley was watching the lights as they serpentined their way to us across the nearly calm water of the bay, idly toying with the now useless combinator.
"Wait here," he said, rising hurriedly. "I must send my motor-boat out there to pick her up and tow her in."
He was gone down the flight of rustic steps on the face of the cliff before we could reply.
"I wish father wouldn't take it to heart so," murmured Gladys. "Sometimes I fear that success or failure of this boat means life or death to him."
"That is exactly why we are here," reassured Kennedy, turning earnestly to her, "to help him to settle this thing at once. This is a beautiful spot," he added, as we stood on the edge of the cliff and looked far out over the tossing waves of the sound.
"What is on that other point?" asked Kennedy, turning again toward the harbour itself.
"There is a large cottage colony there," she replied. "Of course many of the houses are still closed so early in the season, but it is a beautiful place in the summer. The hotel over there is open now, though."
"You must have a lively time when the season is at its height," ventured Kennedy. "Do you know a cottager there, a Mrs. Brainard?"
"Oh, yes, indeed. I have known her in Washington for some time."
"No doubt the cottagers envy you your isolation here," remarked Kennedy, turning and surveying the beautifully kept grounds. "I should think it would be pleasant, too, to have an old Washington friend here."
"It is. We often invite our friends over for lawn-parties and other little entertainments. Mrs. Brainard has just arrived and has only had time to return my first visit to her, but I expect we shall have some good times this summer."
It was evident, at least, that Gladys was not concealing anything about her friend, whether there was any suspicion or not of her.
We had gone into the house to await the return of Captain Shirley. Burke had just returned, his face betraying that he was bursting with news.
"She's here, all right," he remarked in an undertone to Kennedy, "in the Stamford cottage—quite an outfit. French chauffeur, two Japanese servants, maids, and all."
"The Stamford cottage?" repeated Gladys. "Why, that is where Mrs. Brainard lives."
She gave a startled glance at Kennedy, as she suddenly seemed to realise that both he and the secret-service man had spoken about her friend.
"Yes," said Burke, noting on the instant the perfect innocence of her concern. "What do you know about Mrs. Brainard? Who, where is, Mr. Brainard?"
"Dead, I believe," Gladys hesitated. "Mrs. Brainard has been well known in Washington circles for years. Indeed, I invited her with us the night of the Manila display."
"And Mr. Nordheim?" broke in Burke.
"N-no," she hesitated. "He was there, but I don't know as whose guest."
"Did he seem very friendly with. Mrs. Brainard?" pursued the detective.
I thought I saw a shade of relief pass over her face as she answered, "Yes." I could only interpret it that perhaps Nordheim had been attentive to Gladys herself and that she had not welcomed his attentions.
"I may as well tell you," she said, at length. "It is no secret in our set, and I suppose you would find it out soon, anyhow. It is said that he is engaged to Mrs. Brainard—that is all."
"Engaged?" repeated Burke. "Then that would account for his being at the hotel here. At least, it would offer an excuse."
Gladys was not slow to note the stress that Burke laid on the last word.
"Oh, impossible," she began hurriedly, "impossible that he could have known anything about this other matter. Why, she told me he was to sail suddenly for Germany and came up here for a last visit before he went, and to arrange to come back on his return. Oh, he could know nothing—impossible."
"Why impossible?" persisted Burke. "They have submarines in Germany, don't they? And rival companies, too."
"Who have rival companies?" inquired a familiar voice. It was Captain Shirley, who had returned out of breath from his long climb up the steps from the shore.
"The Germans. I was speaking of an attaché named Nordheim."
"Who is Nordheim?" inquired the captain.
"You met him at the Naval building, that night, don't you remember?" replied Gladys.
"Oh, yes, I believe I do—dimly. He was the man who seemed so devoted to Mrs. Brainard."
"I think he is, too, father," she replied hastily. "He has been suddenly called to Berlin and planned to spend the last few days here, at the hotel, so as to be near her. She told me that he had been ordered back to Washington again before he sailed and had had to cut his visit short."
"When did you first notice the interference with the Turtle?" asked Burke. "I received your message this morning."
"Yesterday morning was the first," replied the captain.
"He arrived the night before and did not leave until yesterday afternoon," remarked Burke.
"And we arrived to-night," put in Craig quietly. "The interference is going on yet."
"Then