"Doctor!" called the captain.
"Here, in a hole," answered a reassuring voice; "throw me a cord, and I shall soon be on the surface of the globe again."
They threw a cord to the doctor, who was at the bottom of a hole about ten feet deep; he fastened it round his waist, and his companions hauled him up with difficulty.
"Are you hurt?" asked Hatteras.
"Not a bit," answered the doctor, shaking his kind face, all covered with snow.
"But how did you tumble down there?"
"Oh, it was the refraction's fault," he answered laughing. "I thought I was stepping across about a foot's distance, and I fell into a hole ten feet deep! I never shall get used to it. It will teach us to sound every step before we advance. Ears hear and eyes see all topsy-turvy in this enchanted spot."
"Can you go on?" asked the captain.
"Oh, yes; the little fall has done me more good than harm."
In the evening the travellers had marched twenty-five miles; they were worn out, but it did not prevent the doctor climbing up an iceberg while the snow-house was being built. The full moon shone with extraordinary brilliancy in the clearest sky; the stars were singularly bright; from the top of the iceberg the view stretched over an immense plain, bristling with icebergs; they were of all sizes and shapes, and made the field look like a vast cemetery, in which twenty generations slept the sleep of death. Notwithstanding the cold, the doctor remained a long time in contemplation of the spectacle, and his companions had much trouble to get him away; but they were obliged to think of rest; the snow-hut was ready; the four companions burrowed into it like moles, and soon slept the sleep of the just.