ine 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 compresse