e that you can detonate them when the time comes?"

"Positive. Everything is working fine. I've done my part of it.
Changing wireless operators gave me just the chance I wanted."

"All right. I guess I'll go now."

"Remember the signal. As soon as the things are detonated I will get
off, some way, by wireless the S O S--as if it came from the fleet, you
understand?"

"Yes--that will be the signal for the dash. Good luck--I'm going ashore
now."

As they passed up the ladder, I could no longer restrain myself.

"Craig," I cried, "this is devilish!"

I thought I saw it all now. In the cases of goods on the _Furious_ were
some terrible infernal machines which had been hidden, to be detonated
by these deadly rays of wireless.

Kennedy was busy, working quickly putting together the parts he had
taken from the two packages we had carried.

As I watched him, I realized that the burning of the Rovigno house was
not the action of an incendiary, after all. It had been done by these
deadly rays, probably by mere accident.

As nearly as I could make it out, there was a counterplot against the
_Furious_. Somewhere was an infernal workshop, possibly hedged about by
doors of steel which ordinary force would find hard to penetrate, but
from which, any moment, this super-criminal might send out his deadly
power.

The more I considered it, while Kennedy worked, the more uncanny it
seemed. This man had rendered the mere possession of explosives more
dangerous to the possessor than to the enemy.

Archimedes had been outdone!

The problem before us now was not only the preservation of American
neutrality, but the actual safety of life.

Through the open hatch I could now hear voices on the deck. One was that
of a woman, which I recognized quickly. It was Julia Rovigno.

"I'll be just as quiet as a mouse," she was saying. "I'll stay in the
cabin--I won't be in the way."

I could not hear the man's voice in reply, but it did not sound like
Rovigno's. It was rather like Gaskell's.

Still, we had heard enough to know that Julia Rovigno was on the yacht,
had insisted on going on the expedition for the excitement of the thing,
just as we had heard over the detectaphone.

"Hadn't we better warn her?" I asked Craig, who had paused in his work
at the sound of voices.

Before he could answer we were plunged in sudden darkness. Someone had
switched out the light that had been shining down through the hatchway.
Before we knew it