The Submarine Mine

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ARTHUR B. REEVE

THE SUBMARINE MINE

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First published in Cosmopolitan, November 1916

This e-book edition: Roy Glashan's Library, 2021
Version Date: 2022-08-26

Produced by Matthias Kaether and Roy Glashan
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Click here for more Craig Kennedy stories

Cosmopolitan, November 1916, with "The Submarine Mine"

Knowledge gained from bacteriological research, as well the use of powerful implements of modern warfare combine to make this one of the most complicated mysteries upon which the wonderful talents of Craig Kennedy have been employed. It is not surprising that Jameson characterizes the scheme as "diabolical," even before its whole extent and purpose are discovered through Craig's scientific detective work.

"HERE'S the bullet. What I want you to do, Professor Kennedy, is to catch the crank who fired it."

Captain Lansing Marlowe, head of the new American ship-building trust, had summoned us in haste to the Bellevue, and had met us in his suite with his daughter Marjorie. Only a glance was needed to see that it was she, far more than her father, who was worried.

"You must catch him," she appealed. "Father's life is in danger. Oh, you simply must!"

I knew Captain Marlowe to be a proverbial fire-eater, but in this case, at least, he was no alarmist. For, on the table, as he spoke, he laid a real bullet.

Marjorie Marlowe shuddered at the mere, sight of it, and glanced apprehensively at him as if to reassure herself. She was a tall, slender girl, scarcely out of her teens, whose face was quite as striking for its character as its beauty. The death of her mother, a few years before, had placed on her much of the responsibility of the captain's household and, with it, a charm added to youth.

More under the spell of her plea than even Marlowe's vigorous urging, Kennedy, without a word, picked up the bullet and examined it. It was one of the modern spitzer type, quite short, and conical in shape.

More under the spell of her plea than even Marlowe's vigorous urging,
Kennedy, without a word, picked up the bullet and examined it.

"I suppose you know," went on the captain eagerly, "that our company is getting ready to launch to-morrow the Usona, the largest liner that has ever been built on this side of the water—the name is made up of the initials of United States of North America. Just now," he added enthusiastically, "is what I call the golden opportunity for American shipping. Why, the shipyards of my company are being worked beyond their capacity."

Somehow, the captain's enthusiasm was contagious. I could see that his daughter felt it, that she was full of fire over the idea. But, at the same time, something vastly more personal weighed on her mind.

"We've had nothing but trouble ever since we laid the keel of that ship," he continued pugnaciously; "strikes, a fire in the yard, delays, about everything that could happen. Lately, we've noticed a motor-boat hanging about the river front of the yards. So I've had a boat of my own patrolling the river."

"No idea," replied Marlowe. "I don't know who owns the boat or who runs it. My men tell me they think they've seen a woman in it sometimes, though. It's all a mystery."

"Oh, yes; let me tell you. Last night, Marjorie and I arrived from Bar Harbor on my yacht for the launching. It's anchored off the yard now. Well, early this morning, while it was still gray and misty, I was up. I'll confess I'm worried over to-morrow. I hadn't been able to forget that cruiser. I was out on the deck, peering into the mist when I'm sure I saw her. I was just giving a signal to the boat we have patrolling when a shot whistled past me and the bullet buried itself in the woodwork of the main saloon back of me. I dug it out of the wood with my knife—so, you see, I got it almost unflattened. That's all I have got, too. The cruiser made a getaway—clean."

"I'm sure it was aimed at him!" Marjorie exclaimed. "I don't think it was chance. Don't you see? They've tried everything else. Now, if they could get my father, the head of the company, that would be a blow that would cripple the trust."

"Marjorie was so alarmed," he confessed, "that nothing would satisfy her but that I should come ashore and stay here at the Bellevue, where we always put up when we are in town."

"I hope you'll pardon me," she excused, hanging up the receiver. "They want me very much down-stairs." Then appealing, she added: "I'll have to leave you with father. But, please, you must catch that crank who is threatening him!"

"You see," explained the captain, as she left us, "I've invited quite a large party to attend the launching, for one reason or another. Marjorie must play hostess. They're mostly here at the hotel."

"It looks almost as if some one had dumdumed it," he remarked finally. "It's curiously done, too. Just look at those grooves!"

Both the captain and I looked. It had a hard jacket of cupro-nickel, like the army bullet, covering a core of softer metal. Some one had notched or scored the jacket as if with a sharp knife, though not completely through it.

"There've been other shots, too," went on Marlowe. "One of my watchmen was wounded in the leg last night. It didn't look like a serious wound, yet the poor fellow seems to be in a bad way, they tell me."

"The wound seems to be all puffed up and very painful. It won't heal; and he seems so weak and feverish. Why, I'm afraid the man will die!"

"Very well; I'll have you driven to the hospital where we have had to take him."

"All right. After you go to the hospital, I'll meet you at the yard at noon. Now, if you'll come downstairs with me, I'll get my car and have you taken to the hospital first."

WE followed Marlowe into the elevator and rode down. In the large parlor, we saw that Marjorie Marlowe had joined a group of the guests, and the captain turned aside to introduce us. Among them, I noticed a striking woman, somewhat older than Marjorie. She turned as we approached and greeted the captain cordially.

"I'm so glad there was nothing serious this morning," she remarked, extending her hand to him.

"Oh, nothing at all, nothing at all!" he returned, holding the hand, I thought, just a bit longer than was necessary. Then he turned to us. "Miss Alma Hillman, let me present Professor Kennedy and Mr. Jameson."

I was not so preoccupied in taking in the group that I did not notice that the captain was more than ordinarily attentive to her. Nor can I say that I blamed him, for, although he might almost have been her father in age, there was a fascination about her that youth does not often possess.

Talking with them had been a young man, slender, good-looking, with almost a military bearing.

Fitzhugh bowed and shook hands, murmured something stereotyped, and turned again to speak to Marjorie.

I watched the young people closely. If Captain Marlowe was interested in Alma, it was more than evident that Fitzhugh was absolutely captivated by Marjorie. And I fancied that Marjorie was not averse to him.

As the conversation ran gaily on to the launching and the gathering party of notables who were expected that night and the next day, I noticed that a dark-eyed, dark-haired, olive-complexioned young man approached and joined us.

Gavira also was welcomed in the party, chatting with animation. It was apparent that the physician was very popular with the ladies, and it needed only half an eye to discern that Fitzhugh was jealous when he talked to Marjorie, while Marlowe but ill concealed his restlessness when Gavira spoke to Alma. As for Alma, she seemed to treat the men impartially.

Just then, a young lady, all in white, passed. Plainly she did not belong to the group, though she was much interested in it. As his eye roved over the parlor, Gavira caught her glance and bowed. She returned it, but her look did not linger. For a moment, she glanced sharply at Fitzhugh, still talking to Marjorie, then at Marlowe and Alma Hillman. She was a pretty little girl with eyes that it is impossible to control. Perhaps there was somewhat of the flirt in her. It was not that that interested me. For there was something almost akin to jealousy in the look she gave the other woman.

The conversation, as usual at such times, consisted mostly of witticisms, and, just at present, we had a rather serious bit of business in hand. Kennedy did not betray any of the impatience that I felt, yet I knew he was glad when Marlowe excused himself and we left the party and passed down the corridor while the captain called his car.

"I don't know how you are going to get at this thing," he remarked, pausing after he had sent a boy for his driver. "But I'll have to rely on you. I've told you all I know. I'll see you at noon at the yard. My man will take you there."

As he turned and left us, I saw that he was going in the direction of the barber shop. Next to it, and in connection with it, though in a separate room, was a manicure. As we passed we looked in. There, at the manicure's table, sat the girl who had gone by us in the parlor and had looked so sharply at Marlowe and Alma.

The boy had told us that the car was waiting at a side entrance, but Kennedy seemed now in no haste to go, the more so when Marlowe, instead of going into the barber shop, apparently changed his mind and entered the manicure's. Craig stopped and watched.

For a moment, the captain paused and spoke, then sat down. Quite evidently he had a keen eye for a pretty face and trim figure. Nor was there any mistaking the pains which the manicure took to please her rich and elderly customer. After watching them a moment, Kennedy lounged over to the desk in the lobby.

"Seems as if she was a good drawing card for the house, doesn't it?" he returned. "Her name is Rae Melzer."

He turned to speak to another guest before Kennedy could follow with another inquiry. As we stood before the desk, a postman arrived with the parcels-post.

"Here's a package addressed to Doctor Fernando Gavira," he said brusquely. "It was broken in the mail—see?"

Kennedy, waiting for the clerk to be free again, glanced casually at the package at first, then with a sudden though concealed interest. I followed his eye. In the crushed box could be seen some thin broken pieces of glass and a wadding of cotton-wool.

As the clerk signed for another package, Craig saw a chance, reached over, and abstracted two or three of the broken pieces of glass, then turned, with his back to the postman and clerk, and examined them.

One, I saw at once, had a rim around it. It was quite apparently the top of a test-tube. The other, to which some cotton-wool still adhered, was part of the rounded bowl. Quickly Craig dropped the pieces into one of the hotel envelopes that stood in a rack on the desk, then, changing his mind about asking more now about the little manicure, strode out of the side entrance, where Marlowe's car was waiting for us.

HURRIEDLY we drove across to the City Hospital, where we had no difficulty in being admitted and finding, in a ward, on a white cot, the wounded guard.

Though his wound was one that should not have bothered him much, it had, as Marlowe said, puffed up angrily and in a most peculiar manner. He was in great pain.

Though he questioned the man, Craig did not get anything out of him except that the shot had come from a cruiser which had been hanging about and was much faster than the patrol-boat.

Puzzled himself, Craig did not say much, but, as he pondered the case, shook his head gravely to himself and finally walked out of the hospital abstractedly.

"We have almost an hour before we are to meet Marlowe at the yard," he considered, as we came to the car. "I think I'll go up to the laboratory first."

IN the quiet of his own workshop, Kennedy carefully examined again the peculiar grooves on the bullet. He was about to scrape it, but paused. Instead, he filled a tube with a soupy solution, placed the bullet in it, and let it stand. Next, he did the same with the pieces of glass from the envelope.

Then he opened a drawer and, from a number of capillary pipettes, selected a plain capillary tube of glass. He held it in the flame of a burner until it was red hot. Then carefully he drew out one end of the tube until it was hair-fine.

Again he heated the other end, but this time he let the end alone, except that he allowed it to bend by gravity, then cool. It now had a siphon curve. Another tube he treated in the same way.

By this time, he was ready to proceed with what he had in mind. He took a glass slide, and on it placed a drop from each of the tubes containing the bullet and the glass.

That done, he placed the bent, larger end of the capillary tubes in turn on each of the drops on the slide. The liquid ascended the tubes by capillary attraction and siphoned over the curve, running, as he turned the tubes up, to the finely pointed ends.

Next, in one watch-glass he placed some caustic soda and in another some pyrogallic acid, from each of which he took just a drop, as he had done before, inclining the tubes to let the fluid gravitate to the throttle-end.

"There's a bubble of air in there," he remarked. "The acid and the soda will absorb the oxygen from it. Then I can tell whether I'm right. By the way, we'll have to hurry if we're to be on time to meet Marlowe in the yard," he announced, glancing at his watch, as he placed the tubes in the electric incubator.

WE were a little late as the chauffeur pulled up at the executive offices at the gate of the shipyard, and Marlowe was waiting impatiently for us. Evidently he wanted action, but Kennedy said nothing yet of what he suspected, and appeared to be interested only in the yard.

In the towering superstructure of the building-slip, we at last came to the huge steel monster itself, the Usona. As we approached, above us rose her bow, higher than a house, with poppets both there and at the stern, as well as bracing to support her. All had been done up to the launching, the stem- and stern-posts set in place, her sides framed and plated up, decks laid, bulkheads and casings completed, even much of her internal fitting done. Marlowe explained to us how the launching-ways were composed of the ground-ways, fastened to the ground, as the name implied, and the sliding-ways that were to move over them. The sliding-ways, he said, were composed of a lower course and an upper course, on which rested the "cradle," fitting closely the side of the ship.

To launch her, she must be lifted slightly by the sliding-ways and cradle from the keel-blocks and bilge-blocks, and this was done by oak wedges, hundreds and hundreds of which we could see, jammed between the upper and lower courses of sliding-ways. Next he pointed out the ribbands which were to keep the sliding-ways on the ground-ways, and at the bow the points on either side where the sliding- and ground-ways were bolted together by two huge timbers, known as sole-pieces.

"You see," he concluded, "it is a gigantic task to lift thousands of tons of steel and literally carry it a quarter of a mile to forty feet of water in less than a minute. Everything has to be calculated to a nicety."

It was all very interesting, and we talked with men whom it was a pleasure to see handling great problems so capably. But none could shed any light on the problem which it was Kennedy's to solve. And yet I felt sure, as I watched Craig, that, unsatisfactory as it appeared to Marlowe and to myself, he was slowly forming some kind of theory or, at least, plan of action in his head.

"You'll find me either here or at the hotel, I imagine," returned Marlowe to Kennedy's inquiry, as we parted from him. "I've instructed all the men to keep their eyes open. I hope some of us have something to report soon."

Whether or not the remark was intended as a hint to Kennedy, it was unnecessary. He was working as fast and as surely as he could.

LATE in the afternoon, we got back to the laboratory, and Craig began immediately to take from the little electric incubator the two crooked tubes he had left there.

Breaking off the ends with tweezers, he began examining, on slides, the two drops that exuded, using his most powerful microscope.

"Well," he remarked at last, looking up from his examination of one of the slides, "here is a drop that shows what was in the grooves of that bullet. Just take a look."

I applied my eye to the microscope. All I could see was some dots and rods, sometimes something that looked like chains of dots and rods, the rods straight, with square ends, sometimes isolated, but more often joined end to end in long strings.

"Anaerobic bacilli and spores," he replied excitedly, "the things that produce the well-known 'gas-gangrene' of the trenches, the gas-phlegmon bacilli—all sorts —actively gas-forming microbes that can't live in air. The method I took to develop and find them was that of Colonel Sir Almroth Wright, of the British Army Medical Corps."

"The spores or seeds," he replied. "In the tubes, by excluding the air, I have developed the bacilli. Why, Walter," he went on seriously, "those are among the microbes most dreaded in the infection of wounds. The spores live in the earth, it has been discovered, especially in cultivated soil, and they are extraordinarily long-lived, lying dormant for years, waiting for a chance, to develop. Those rods you saw are only from five to fifteen thousandths of a millimeter long and not more than one-thousandth of a millimeter broad.

"You can't see them move here, because the air has paralyzed them. But these vibrios move among the corpuscles of the blood just as a snake moves through the grass, to quote Pasteur. If I colored them, you would see that each is covered with fine vibrating hairs three or four times as long as itself. At certain times, an oval mass forms in them. That is the spore, which lives so long and is so hard to kill. It was the spores that were on the bullet. They resist any temperature except comparatively high and prolonged ones, and even resist antiseptics for a long time. On the surface of a wound, they aren't so bad; but, deep in, they distil minute gas bubbles, puff up the surrounding tissues, and are almost impossible to combat."

I could only stare at him while the diabolical nature of the attack impressed itself on my mind. Some one had tried to murder Marlowe in this most hideous way. No need to be an accurate marksman when a mere scratch from such a bullet meant ultimate death anyhow.

I could only stare at him while the diabolical
nature of the attack impressed itself on my mind.

Why had it been done, and where had the cultures come from? I realized fully the difficulty of trying to trace them. Anyone could purchase germs, I knew. There was no law governing their sale.

"Here, on this other film, I find the same sort of wisp-like anaerobes," he announced. "There was the same thing on those pieces of glass that I got from that broken package that came to the hotel."

"Then it was Gavira who was receiving spores and cultures of the anaerobes!" I exclaimed excitedly.

"But that doesn't prove that it was he who used them," cautioned Craig, adding: "Not yet, at least. I think the best thing for us to do will be to run over to the Bellevue. I should like to see Marlowe again and, besides, there we can watch some of these people around him."

MARLOWE was out when we arrived; in fact, had not yet returned from the yard. Nor had many of the guests remained at the hotel during the day. Most of them had been out sightseeing, though now they were returning, and, as they began to gather in the hotel parlor. Marjorie was again called on to put them at their ease.

Fitzhugh had returned, and had wasted no time in dressing and getting down-stairs again to be near Marjorie. Gavira also appeared, having been out on a case.

"I wish you would call up the shipyard, Walter," said Kennedy, as we stood in the lobby, where we could see best what was going on. "Tell Marlowe I would like to see him very urgently."

I found the number and entered a booth, but, as often happens, the telephone central was overwhelmed by the rush of early-evening calls, and the only satisfaction I got was that the line was busy. From where I stood, I could see that Kennedy was closely watching the little manicure, Rae Melzer.

A moment later, I saw Alma Hillman come out of the manicure shop, and before anyone else could get in, I saw Craig saunter over and enter.

I was so interested in what he was doing that, for the moment, I forgot about my call, and found myself unconsciously moving over in that direction, too. As I looked in, I saw that he was seated at the little white table, deep in conversation with the girl.

Once she turned to reach something on a shelf back of her. Quick as a flash. Kennedy abstracted a couple of the nearest implements, one being a nail-file and the other, I think, a brush.

Once she turned to reach something on a shelf back of her.
Quick as a flash. Kennedy abstracted a couple of the nearest im-
plements, one being a nail-file and the other, I think, a brush.

A moment later, she resumed her work, Kennedy still talking and joking with her, though furtively observing.

"Where is my nail-file and brush?" I could imagine her saying, as she hunted for them in pretty confusion, aided by Kennedy, who, when he wanted to, could act the Fitzhugh and Gavira as well as they.

"Kennedy's cut you out," he laughed, catching a glimpse through the door. "Never mind; I used to think I had some influence there myself—till the captain came along. I tell you, these oldsters can give us points."

I laughed, too, and joined him down the hall, not because I cared what he thought but because his presence had reminded me of my original mission to call up Marlowe. However, I decided to postpone calling another moment and talk to the house-physician.

"Yes," I agreed; "I fancy the captain likes young people. He seems to enjoy being with them—Miss Hillman, for instance."

"The Bellevue's a dangerous place for a wealthy widower," he returned. "I had some hopes in that direction myself, but the captain seems to leave us all at the post. Still, I suppose I may still be a brother to her—and physician. So, I should worry."

The impression I got of Gavira was that he enjoyed his freedom too much ever to fall in love, though an intimacy now and then with a clever girl like Alma Hillman was a welcome diversion.

"I'm sorry I shan't be able to be with you until late to-night," he said, as he paused at his office door. "I'm in the medical corps of the guard, and I promised to lecture to-night on gunshot wounds. Some of my material got smashed up, but I have my lantern-slides, anyhow. I'll try to see you all later, though."

Was that a clever attempt at confession and avoidance on his part, I wondered. But, then, I reflected he could not possibly know that we knew he had anaerobic microbes and spores in his possession. I had cleared up nothing, and I hastened to call up the shipyard again.

WHATEVER it was that was the matter, central seemed unable to get me my number. Instead, I found myself cut right into a conversation that did not concern me, evidently the fault of the hotel-switchboard operator. I was about to protest, when the words I heard stopped me in surprise. A man and a woman were talking, though I could not recognize the voices, and no names were used.

"I tell you I won't be a party to that launching scheme," I heard the man's voice say. "I told you that all along."

"Then you're going to desert us?" came back the woman's voice rather tartly. "It's for that girl—well, you'll regret it. I'll turn the whole organization on you—I will, you—you——"

He listened keenly as I told him what I had heard, adding also about my encounter with Gavira.

"Well, anything new? I expected to hear from you, but haven't," boomed the deep voice of Marlowe, who had just come in. "No clue yet to my crank?"

"It's no crank," he whispered. "Marlowe, I am convinced that there is a concerted effort to destroy your plans for American commerce-building. There isn't the slightest doubt in my mind that it is more serious than you think—perhaps a powerful group of European steamship men opposed to you. It is economic war!"

Half doubting, half convinced, Marlowe drew back. One after another, he shot a rapid fire of questions. Who, then, was their agent who had fired the shot? Who was it who had deserted, as I had heard over the wire? Above all, what was it they had planned for the launching? The deeper he got, the more the beads of perspiration came out of his sunburned forehead. The launching was only eighteen hours off, too, and ten of them were darkness. What could be done?

"I'll need it only a few hours. I think I have a scheme that will work perfectly—if you are sure you can guard the inside of the yard to-morrow."

"I'm sure of that. We spent hours to-day selecting picked men for the launching, going over everything."

LATE as it was to start out of town, Craig drove across the bridge and out on Long Island, never stopping until we came to a small lake, around the shores of which he skirted, at last pausing before a huge, barn-like structure.

As the door swung open to the honking of his horn, the light which streamed forth shone on a sign above—"Sprague Aviation School." Inside, I could make out enough to be sure that it was an aeroplane hangar.

Craig jumped from the car, and together the two went into the hangar, while I followed. They talked in low tones, but I could make out that Kennedy was hiring a hydro-aeroplane for the morrow.

As Kennedy and his acquaintance, Sprague, came to terms, my eye fell on a peculiar gun set up in a corner. It had a tremendous cylinder about the barrel as though it contained some device to cool it. It was not a machine gun of the type I had seen, however, yet cartridges seemed to be fed to it from a disk, on which they were arranged radially, rather than from a band.

"Oh, a Lewis gun!" he exclaimed, seeing what I was looking at. "That's an idea! Sprague, can you mount that on the plane?"

"Oh, a Lewis gun!" he exclaimed, seeing what I was looking at.
"That's an idea! Sprague, can you mount that on the plane?"

"That's what I have it here for," he returned. "I've been testing it. Why? Do you want it?"

Speeding back to the city, Kennedy laid out the program for me to follow on the morrow. Together we arranged an elaborate series of signals, and that night, late as it was, Craig returned to the laboratory, where he continued his studies with the microscope.

IN spite of his late hours, it was Craig who wakened me in the morning, already prepared to motor out to the aviation school and meet Sprague.

Hastily he rehearsed our signals, which consisted mostly of dots and dashes in the Morse code, which Craig was to convey with a flag and I to receive with the aid of a powerful glass.

I must admit that I felt somewhat lost without Craig when, later in the morning, I took my place alone on the platform that had been built for the favored few of the launching-party at the bow of the huge Usona. Already, however, he had communicated at least a part of his plan to Marlowe, and the captain and Marjorie were among the first to arrive. Marjorie never looked prettier in her life than she did now, on the day when she was to christen the great liner.

They had scarcely greeted me when we heard a shout from the men down at the end of the ship that commanded a freer view of the river. We craned our necks and in a moment saw what it was. They had sighted the hydro-aeroplane coming down the river.

I turned the glass on the mechanical bird as it soared closer. Already, Kennedy had seen us on the platform and had begun to signal as a test. At least a part of the suspense was over for me when I discovered that I could read what he sent.

So fixed had my attention been that I had not noticed that slowly the members of the launching-party had arrived, while other thousands of the less favored crowded into spaces set apart for them. On the stand now with us were Fitzhugh and Miss Hillman, while, between glances at Kennedy, I noticed little Rae Melzer over at the right, and Doctor Gavira, quite in his element, circulating about from one group to another.

Down in the slip, the men were driving home the last of the huge oak wedges which lifted the great Usona from the blocks and transferred her weight to the launching-ways as a new support. All along the stationary or ground-ways and those which were to glide into the water with the cradle and the ship, trusted men were making the final examinations.

As the clock neared noon, which was high water approximately, all the preparatory work was done. Only the sole-pieces before us held the ship in place.

High overhead, floated the hydro-aeroplane, on which I kept my eye fixed almost hypnotically. There was still no signal from Kennedy, however. What was it he was after? Did he expect to see the fast express cruiser lurking like a corsair about the islands of the river?

Men were quitting now the work of giving the last touches to the preparations. Some were placing immense jack-screws which were to give an initial impulse, if it were needed, to start the ship down the ways. Others were smearing the last heavy dabs of tallow, lard oil, and soft soap on the ways, and graphite where the ways stretched two hundred feet or so out into the water, for the ship was to travel some hundreds of feet on the land and in the water and perhaps an equal distance out beyond the end of the ways. Men now reported that everything was ready. Steadily the time of high water approached.

That was a thing that must be done by two gangs, one on each side, and evenly, too. If one gang got ahead of the other, it must stop and let the second catch up.

Suddenly, I saw Craig's flag waving frantically. A muffled exclamation came from my lips involuntarily. Marlowe, who had been watching me, leaned closer.

Kennedy was circling down now until, at last, the air-boat rested on the water and skimmed along toward the ways.

Out on the ways, as far as they were not yet submerged, some men ran, as if to meet him, but Kennedy began signaling frantically again.

"He wants them to keep back!" I called, and the word was passed down the length of the ship.

Instead of coming to rest before the slip, the plane turned and went away, making a complete circle, then came to rest.

To the surprise of everyone, 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 rose in the air about eight hundred feet out in the river 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 rush to the river would have hit that mine, tilting it, she would have sunk in a blast of flame.

The air-boat now headed for the shore, 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.

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

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.

Wedges, sliding-ways, and other parts of the cradle floated to the surface. The tide took the ship, 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'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 the plotters' agent? I have something here that will interest you."

Kennedy was speaking rapidly. It was one of those occasions in which his 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-percent, 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 cleansing don'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 Bellevue, and——"

"They were stolen from me. Some one must have got into my office, where I was studying them."

"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."

"Love has saved him. But the other? To whom do these deadly germs point? Who dumdumed 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!"

THE END