d 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 submar