“Nonsense,” he said. “It can’t be.”
“But it is, I tell you.”
“Let me try it.”
The professor gave a hard tug, but still the cord did not budge.
“Give me a hand here,” he said to Nat, and together they tugged.
Suddenly, and without the least warning, the cord broke off short in their hands, and they fell sprawling on the floor. To his astonishment, when Nat tried to rise, he found the task difficult. Breathing seemed to be a labor, and his limbs felt like lead. The professor had actually to be helped to his feet, and then staggered, with one hand over his heart, to the helmsman’s settee, on which he sank, breathing with a queer, whistling sound.
“What on earth has happened?” demanded Joe, who like the others, felt strangely oppressed and heavy. His head ached as if it would burst.
“The—the cord must have frozen to the sides of the bag,” gasped out the professor. “The change to this awful altitude turned the night moisture accumulated on the gas bag’s sides to ice. I fear we are doomed, unless——”
He paused, panting and gasping.
“Unless what?” demanded Nat, forcing the words out.