"Then you do not care for me, at all?"

"I do, but only as an acquaintance."

"Not even as a friend?"

"I do not like to answer such pointed questions, sir; but, since you ask, I will tell you. I do not like you, even as a friend. You demand so much. You are very selfish, never considering my feelings at all, and you often annoy me with your moods. Frankly, I am happier away from you."

"My moods!" Foster repeated, bitterly. "You cause my moods. But I know what the real trouble is. I was all right until Ross came along."

"You have no right, Mr. Foster," said the girl, angrily, "to bring Lieutenant Ross' name into this discussion."

"Oh, I understand. Do you think he can marry you on his pay?"

"Mr. Ross' pay would not influence him, nor me."

"Well, I'll tell you this"--and Foster's voice became a snarl--"you two won't be married. I'll see to it. I want you; and if I can't have you, no one else shall."

"Whew!" whistled Ross, softly, while he smiled sweetly, and danced a mental jig in the air. Then he danced a few steps of a real jig, to apprise them of his coming. "Time to end this," he said; then called out, cheerily: "Look out below," and entered the hatch.

"Got a bad habit," he said, as he descended, "of coming down this ladder by the run. Must break myself, before I break my neck. Well, how are you making out? Been looking around?"

The girl's face, pale but for two red spots in her cheeks, was turned away from him as he stepped off the ladder, and she trembled visibly.

Foster, though flushed and scowling, made a better effort at self-control.

"Why, no, lieutenant," he said, with a sickly smile. "It is all strange and new to us. We were waiting for you. But I have become slightly interested in this--" He indicated a circular window, fixed in the steel side of the boat. "Isn't it a new feature in submarines?"

"Yes, it is," answered Ross. "But it has long been known that glass will stand a stress equal to that of steel, so they've given us deadlights.

See the side of the ship out there? We can see objects about twenty feet away near the surface. Deeper down it is darker."

"And I suppose you see some interesting sights under water," pursued Foster, now recovered in poise.

"Yes, very interesting--and some very harrowing. I saw a man drowning not long ago. We were powerless to help him."

"Heavens, what a sight!" exclaimed Foster. "The expression on his face must have been tragic."

"Pitiful--the most pitiful I ever looked at. He seemed to be calling to us. Such agony and despair; but it did not last long."

"But while it _did_ last--did you have a camera? What a chance for a photographer! That is my line, you know. Did ever a photographer get a chance to photograph the expression on the face of a drowning man? What a picture it would be?"

"Don't," said the girl, with a shudder. "For mercy's sake, do not speak of such things."

"I beg your pardon, Miss Fleming," said Ross, gently. "It was very tactless in me."

"And I, Miss Fleming," said Foster, with a bow, "was led away by professional enthusiasm. Please accept _my_ apology, too. Still, lieutenant, I must say that I would like the chance."

"Sorry, Mr. Foster," answered Ross, coldly. "We do all sorts of things to men in the navy, but we don't drown them for the sake of their pictures. Suppose I show you around, for at two bells the men will be back from their dinner. Now, aft here, is the gasoline engine, which we use to propel the boat on the surface. We can't use it submerged, however, on account of the exhaust; so, for under-water work, we use a strong storage battery to work a motor. You see the motor back there, and under this deck is the storage battery--large jars of sulphuric acid and lead. It is a bad combination if salt water floods it."

"How? What happens?" asked Foster.

"Battery gas, or, in chemical terms, chlorine gas is formed. It is one of the most poisonous and suffocating of all gases. That is the real danger in submarine boats--suffocation from chlorine. It will remain so until we get a better form of motive power, liquid or compressed air, perhaps. And here"--Ross led them to a valve wheel amidships--"as though to invite such disaster, they've given us a sea cock."

"What's it for?" asked Foster.

"To sink the boat in case of fire. It's an inheritance from steamboats--pure precedent--and useless, for a submarine cannot catch fire. Why, a few turns of that wheel when in the awash trim would admit enough water in two minutes to sink the boat. I've applied for permission to abolish it."

"Two minutes, you say. Does it turn easy? Would it be possible to accidentally turn it?"

"Very easy, and very possible. I caution my men every day."

"And in case you do sink, and do not immediately suffocate, how do you rise?"

"By pumping out the water. There's a strong pump connected with that motor aft there, that will force out water against the pressure of the sea at fifty fathoms down. That is ten atmospheres--pretty hard pressure. But, if the motor gets wet, it is useless to work the pump; so, we can be satisfied that, if we sink by means of the sea cock, we stay sunk. There is a hand pump, to use on the surface with dead batteries, but it is useless at any great depth."

"What do you mean by the awash trim, lieutenant?" asked Foster, who was now looking out through the deadlight.

"The diving trim--that is, submerged all but the conning-tower. I'll show you, so that you can say that you have really been under water."

Ross turned a number of valves similar to the sea cock, and the girl's face took on a look of doubt and sudden apprehension.

"You are not going to sink the boat, are you, Mr. Ross?" she asked.

"Oh, no, just filling the tanks. When full, we still have three hundred pounds reserve buoyancy, and would have to go ahead and steer down. But we won't go ahead. Come forward, and I'll show you the torpedo-tube."

Foster remained, moodily staring through the deadlight, while the other two went forward. Ross noticed his abstraction, and, ascribing it to weariness of technical detail, did not press him to follow, and continued his lecture to Miss Fleming in a lower tone and in evident embarrassment.

"Now, here is the tube," he said. "See this rear door. It is water-tight. When a torpedo is in the tube, as it is now, we admit water, as well; and, to expel the torpedo, we only have to open the forward door, apply compressed air, and out it goes. Then it propels and steers itself. We have a theory--no, not a theory now, for it has been proved--that, in case of accident, a submarine's crew can all be ejected through the tube except the last man. He must remain to die, for he cannot eject himself. That man"--Ross smiled and bowed low to the girl--"must be the commander."

"How terrible!" she answered, interested, but looking back abstractedly at Foster. "Why do you remain at this work? Your life is always in danger."

"And on that account promotion is more probable. I want promotion, and more pay"--he lowered his voice and took her hand--"so that I may ask for the love and the life companionship of the dearest and best girl in the world."

She took her gaze off Foster, cast one fleeting glance into the young lieutenant's pleading face, then dropped her eyes to the deck, while her face flushed rosily. But she did not withdraw her hand.

"Must you wait for promotion?" she said, at length.

"No, Irene, no," exclaimed Ross, excitedly, squeezing the small hand in his own. "Not if you say so; but I have nothing but my pay."

"I have always been poor," she said, looking him frankly in the face.

"But, John, that is not it. I am afraid. He--Mr. Foster, threatened us--vowed we would never-- Oh, and he turned something back there after you started. He did it so quickly--I just barely saw him as I turned to follow you. I do not know what it was. I did not understand what you were describing."

"He turned something! What?"

"It was a wheel of some kind."

Ross looked at Foster. He was now on the conning-tower ladder, half-way up, looking at his opened watch, with a lurid, malevolent twist to his features.

"Say your prayers!" yelled Foster, insanely. "You two are going to die, I say. Die, both of you."