the German professor was working away.

"He came up at supper time, humming cheerfully to himself, and
announced that he had replaced his camera lens with the rock crystal,
that the lantern, with its reflector and a blue spark in the focus,
made an admirable instrument for throwing the invisible rays on the
beast, and that he was all ready, except that his plates, which he had
resensitized--with some phosphorescent substance that I forget the name
of, now--must have time to dry. And then, he needed some light to work
by when the time came, he explained.

"'Also another victim,' I suggested bitterly; for he had not been on
deck when the last two men had died.

"'I hope not,' he said. 'When we can see, it may be possible to stir
him up by throwing things forward; then when he moves der water we can
take shots.'

"'Better devise some means of killing him,' I answered. 'Shooting won't
do, for water stops a bullet before it goes a foot into it.'

"'Der only way I can think of,' he responded, 'is for der next man--you
hear me all, you men--to stick your knife at the end of the
blood--where it collects in a lump. Dere is der creature's stomach, and
a vital spot.'

"'Remember this, boys,' I laughed, thinking of the last poor devil,
with his arms pinioned to his side. 'When you've lost enough blood to
see it in a lump, stab for it.'

"But my laugh was answered by a shriek. A man lashed with a turn of
rope around his waist to the stump of the mizzenmast, was writhing and
heaving on his back, while he struck with his knife, apparently at his
own body. With my own knife in my hand I sprang toward him, and felt
for what had seized him. It was something cold, and hard, and leathery,
close to his waist.

"Carefully gauging my stroke, I lunged with the knife, but I hardly
think it entered the invisible fin, or tail, or paw of the monster; but
it moved away from the screaming man, and the next moment I received a
blow in the face that sent me aft six feet, flat on my back. Then came
unconsciousness.

"When I recovered my senses the remnant of the crew were around me, but
the man was gone--dragged out of the bight of the rope that had held
him against the force of breaking seas, and down to the flooded main
deck, to die like the others. It was too dark to see, or do anything;
so, when I could speak I ordered all hands but one into the flooded
cabin where, in the upper berths and on the top of the table, were a
few dry spots.