was dying out of sight, till it was perfectly invisible; and yet it
was clear about where they were, only for a few minutes, though. Then
there was a faint, gauzy film close by, into which they rowed, and as
they passed completely in, the _Hvalross_ was almost hidden; five
minutes later it was not to be seen.

The mist was upon them, thickening each moment, and a curiously
depressing chill came over the boy. It was as if the cold were
attacking his mind as well as his body, and he quite started as the deep
voice of Johannes said, the words sounding muffled:

"Keep your helm fast, sir. We mustn't miss the ship."

"Mustn't miss the ship," thought Steve, with a strange sense of dread
creeping over him now like another and darker mist. "If we did miss
her, what then?"

CHAPTER TWELVE.

A STRANGE PERIL.

It seemed hard to believe, so rapidly had the change taken place. Only
a few minutes before, and they were gliding along with the blue sky
above and the air perfectly clear; now everything was shut out, even
Johannes in the bows of the boat looking indistinct from where Steve and
the captain were seated in the stern.

Captain Marsham made no verbal reply to the warning of the Norseman, but
his right arm which held the steering oar grew rigid, and he did not
stir from his position.

Steve was no experienced sailor, but he had seen plenty of the last fog,
and as he sat there growing anxious the following problem presented
itself to him after the fashion of the mathematical studies at school,
and based on the difficulty of making a way through what was little
better than black darkness. Let A, B, and C represent the points of a
triangle. If three parties start together from those points to reach a
common centre, and travel at different rates of speed, when will they
meet?

"It looks as if the answer is--never," thought Steve. "Why, the
_Hvalross_ is steaming faster--we saw her; and she'll go right on and
leave us behind. This fog, too, may last for days."

"Keep cool, my lad," said the captain in a low voice; "we shall soon be
on board. Listen, and try if you can hear the beat of the propeller."

Those words sent a hopeful thrill through the boy, just as his spirits
were getting very low indeed, and he leaned over the boat's side
listening, but the regular dip, dip of the oars was all he could
distinguish. He did not speak; there was no need.

"Steady!" cried the captain suddenly, and his voice sou