Instead of coming to rest before the slip, the plane turned and went away, making a complete circle, then coming to rest. To the surprise of every one, the rapid staccato bark of the Lewis gun broke the silence.

Kennedy was evidently firing, but at what? There was nothing in sight.

Suddenly there came a tremendous detonation, which made even the launching-slip tremble, and a huge column of water, like a geyser, rose in the air about eight hundred feet out in the river, directly in front of us.

The truth flashed over us in an instant. There, ten feet or so in the dark water out in the river, Craig had seen a huge circular object, visible only against a sandy bottom from the hydro-aeroplane above, as the sun-rays were reflected through the water. It was a contact submarine mine.

Marlowe looked at me, his face almost pale. The moment the great hulk of the Usona in its wild flight to the sea would have hit that mine, tilting it, she would have sunk in a blast of flame.

The air-boat now headed for the sh.o.r.e, and a few moments later, as Craig climbed into our stand, Marlowe seized him in congratulation too deep for words.

"Is it all right?" sang out one of the men in the gangs, less impressionable than the rest.

"If there is still water enough," nodded Craig.

Again the order to saw away the sole pieces was given, and the gangs resumed. "Zip--zip," again went the two saws.

There were perhaps two inches more left, when the hull quivered. There was a crashing and rending as the timbers broke away.

Marjorie Marlowe, alert, swung the bottle of champagne in its silken net on a silken cord and it crashed on the bow as she cried, gleefully, "I christen thee Usona!"

Down the ship slid, with a slow, gliding motion at first, rapidly gathering headway. As her stern sank and finally the bow dipped into the water, cheers broke forth. Then a cloud of smoke hid her. There was an ominous silence. Was she wrecked, at last, after all? A puff of wind cleared the smoke.

"Just the friction of the ways--set the grease on fire," shouted Marlowe. "It always does that."

Wedges, sliding ways, and other parts of the cradle floated to the surface. The tide took her and tugs crept up and pulled her to the place selected for temporary mooring. A splash of a huge anchor, and there she rode--safe!

In the revulsion of feeling, every eye on the platform turned involuntarily to Kennedy. Marlowe, still holding his hand, was speechless. Marjorie leaned forward, almost hysterical.

"Just a moment," called Craig, as some turned to go down. "There is just one thing more."

There was a hush as the crowd pressed close.

"There's a conspiracy here," rang out Craig's voice, boldly, "a foreign trade war. From the start I suspected something and I tried to reason it out. Having failed to stop the work, failed to kill Marlowe--what was left? Why, the launching. How? I knew of that motor-boat. What else could they do with it? I thought of recent tests that have been made with express cruisers as mine-planters. Could that be the scheme? The air-boat scheme occurred to me late last night. It at least was worth trying. You see what has happened. Now for the reckoning. Who was their agent? I have something here that will interest you."

Kennedy was speaking rapidly. It was one of those occasions in which Kennedy's soul delighted. Quickly he drew a deft contrast between the infinitely large hulk of the Usona as compared to the infinitely small bacteria which he had been studying the day before. Suddenly he drew forth from his pocket the bullet that had been fired at Marlowe, then, to the surprise of even myself, he quietly laid a delicate little nail file and brush in the palm of his hand beside the bullet.

A suppressed cry from Rae Melzer caused me to recollect the file and brush she had missed.

"Just a second," raced on Kennedy. "On this file and brush I found spores of those deadly anaerobes--dead, killed by heat and an antiseptic, perhaps a one-per-cent. solution of carbolic acid at blood heat, ninety-eight degrees--dead, but nevertheless there. I suppose the microscopic examination of finger-nail deposits is too minute a thing to appeal to most people. But it has been practically applied in a number of criminal cases in Europe. Ordinary washing and even cleaning doesn't alter microscope findings. In this case this trifling clue is all that leads to the real brain of this plot, literally to the hand that directed it." He paused a moment.

"Yesterday I found that anaerobe cultures were being received by some one in the Belleclaire, and--"

"They were stolen from me. Some one must have got into my office, where I was studying them." Doctor Gavira had pressed forward earnestly, but Craig did not pause again.

"Who were these agents sent over to wage this secret war at any cost?"

he repeated. "One of them, I know now, fell in love with the daughter of the man against whom he was to plot." Marjorie cast a furtive glance at Fitzhugh.

"Love has saved him. But the other? To whom do these deadly germs point? Who dum-dummed and poisoned the bullet? Whose own fingers, in spite of antiseptics and manicures, point inexorably to a guilty self?"

Rae Melzer could restrain herself no longer. She was looking at the file and brush, as if with a hideous fascination. "They are mine--you took them," she cried, impulsively. "It was she--always having her nails manicured--she who had been there just before--she--Alma Hillman!"

XI

THE GUN-RUNNER

"With the treaty ratified, if the deal goes through we'll all be rich."

Something about the remark which rose over the babel of voices arrested Kennedy's attention. For one thing, it was a woman's voice, and it was not the sort of remark to be expected from a woman, at least not in such a place.

Craig had been working pretty hard and began to show the strain. We had taken an evening off and now had dropped in after the theater at the Burridge, one of the most frequented midnight resorts on Broadway.

At the table next to us--and the tables at the Burridge were so close that one almost rubbed elbows with those at the next--sat a party of four, two ladies in evening gowns and two men in immaculate black and white.

"I hope you are right, Leontine," returned one of the men, with an English accent. "The natural place for the islands is under the American flag, anyway."

"Yes," put in the other; "the people have voted for it before. They want it."

It was at the time that the American and Danish governments were negotiating about the transfer of the Danish West Indies, and quite evidently they were discussing the islands. The last speaker seemed to be a Dane, but the woman with him, evidently his wife, was not. It was a curious group, worth more than a pa.s.sing glance. For a moment Craig watched them closely.

"That woman in blue," he whispered, "is a typical promoter."

I recognized the type which is becoming increasingly frequent in Wall Street as the compet.i.tion in financial affairs grows keener and women enter business and professional life.

There were plenty of other types in the brilliantly lighted dining-room, and we did not dwell long on the study of our neighbors. A few moments later Kennedy left me and was visiting another table. It was a habit of his, for he had hundreds of friends and acquaintances, and the Burridge was the place to which every one came.

This time I saw that he had stopped before some one whom I recognized.

It was Captain Marlowe of the American Shipping Trust, to whom Kennedy had been of great a.s.sistance at the time of the launching of his great ship, the Usona. Marlowe's daughter Marjorie was not with him, having not yet returned from her honeymoon trip, and he was accompanied by a man whose face was unfamiliar to me.

As I recognized who it was to whom Kennedy was speaking, I also rose and made my way over to the table. As I approached, the captain turned from Kennedy and greeted me cordially.

"Mr. Whitson," he introduced the man with him. "Mr. Whitson is sailing to-morrow for St. Thomas on the Arroyo. We're preparing to extend our steamship lines to the islands as soon as the formalities of the purchase are completed."

Marlowe turned again to Kennedy and went on with the remark he had evidently been making.

"Of course," I heard him say, "you know we have Mexico practically blockaded as far as arms and munitions go. Yet, Kennedy, through a secret channel I know that thousands of stands of arms and millions of rounds of ammunition are filtering in there. It's shameful. I can't imagine anything more traitorous. Whoever is at the bottom of it ought to swing. It isn't over the border that they are going. We know that.

The troops are there. How is it, then?"

Marlowe looked at us as if he expected Kennedy to catch some one by pure reason. Kennedy said nothing, but it was not because he was not interested.

"Think it over," pursued Marlowe, who was a patriot above everything else. "Perhaps it will occur to you how you can be of the greatest service to the country. The thing is d.a.m.nable--d.a.m.nable."

Neither Kennedy nor I having anything definite to contribute to the subject, the conversation drifted to the islands and Whitson's mission.

Whitson proved to be very enthusiastic about it. He knew the islands well and had already made a trip there for Marlowe.