When the young inventor awoke he looked below and could see nothing—nothing but a sea of mist.
"What's this?" he cried. "Are we above the clouds, or in a fog over some inland sea?"
He was quite worried, until Ivan Petrofsky informed him that they were in the midst of a dense fog, which was common over that part of Siberia.
"But where are we?" asked Ned.
"About over the province of Irtutsk," was the answer. "We are heading north," he went on, as he looked at the compass, "and I think about right to land somewhere near where my brother is confined in the sulphur mine."
"That's so; we've got to drop," said Tom. "I must get the gas pipe repaired. I wish we could see over what sort of a place we were so as to know whether it would be safe to land. I wish the mist would clear away."
It did, about noon, and they noted that they were over a desolate stretch of country, in which it would be safe to make a landing. Bringing the aeroplane down on as smooth a spot as he could pick out, Tom and Ned were soon at work clearing out the clogged pipe of the gas generator. They had to take it out in the open air, as the fumes were unpleasant, and it was while working over it that they saw a shadow
