t amazingly rapid for one under water, the
stranger leaped upon him, at the same time drawing a long knife. There,
under the sea, commenced a battle royal.

Locke was unarmed and so from the start was at a disadvantage. The
stranger seemed not so anxious to stab him as to come to close quarters,
and before Locke could prevent him he had done so. With his left hand he
grabbed Locke's lines, while with the other, in which was the keen
knife, he slashed murderously.

Locke tried to break his grip. But the other was not to be denied. With
one stroke he cut through both lines, pushing Locke backward and himself
springing free at the same time.

Immediately Locke's helmet filled with sea water, while the pressure
became enormous. Locke tried to hold his breath, while his hand searched
for the liberating knob. He gave it one twist. It worked perfectly.
Locke's suit, including the helmet, simply opened and fell from him.

Propelled as much by the pressure that the water exerted as by his own
powerful strokes, Locke shot to the surface.

The day was perfect and the bay was calm. For a few seconds Locke
floated, drawing the air into his starving lungs. Then he raised himself
and gazed about him. At first glance everything seemed the same except
for the fact that, whereas before his own boat had been alone, there
were now two. Then Locke heard an agonizing call for help--from Eva.

After he had gone over the side of their launch Eva was naturally very
intent upon keeping him plentifully supplied with air. He had been down
some time before, glancing about, she had spied the other launch. But at
the time she had thought little of it. For her, all thought of danger
was centered on the man who was now risking his life many fathoms
beneath her from pure motives of patriotism.

It was only, some minutes later, when she heard the grating of another
boat against the side of her own that she realized that she herself
stood in danger. But even at that moment her thoughts were of Quentin,
who now for the first time was wholly dependent on her efforts alone.
She looked up fearfully, and what she saw fairly congealed the blood in
her veins. Directing a murderous emissary to board Eva's launch, in the
cockpit of the other boat stood the Automaton!

Not for an instant did Eva cease her efforts at the pump. But she
shrieked with terror again and again. Now, to add to that terror, the
pressure on the air-pump suddenly ceased. From the dept