The three boys were strong and they pulled with all their might, but for a time it seemed doubtful if they could lift the professor out of the crevasse as, despite his leanness, he was a fairly heavy man. He aided them, however, by digging his heels in the wall of the crevasse as they hoisted and in ten minutes' time they were able to grasp his hands and pull him into safety.
A draught from the vacuum bottle containing hot coffee which Frank carried soon restored the professor and he was able to describe to them how, as he was walking along, declaiming concerning the fur-bearing pollywog, the ground seemed to suddenly open under his feet and he felt himself tumbling into an abyss of unknown depth.
As the chasm narrowed, he managed to jam himself partially across the rift and in this way encountered an ice-coated ledge. One glance down showed him that if he had not succeeded in doing this his plunge would have ended in death, for the crevasse seemed to exist to an unknown depth beneath the surface of the earth.
"And now that I am safe and sound," said the professor, "let us hurry on. The fall hasn't reduced my eagerness to see the wrecked Viking ship."
"But the crevasse, how are we to pass that?" asked Frank.
"We must make a detour to the south," said the professor, "I noticed when I was down there that the rift did not extend more than a few feet in that direction. In fact, had I dared to move I might have clambered out."
The boys, not without some apprehension, stepped forward in continuance of their journey, and a few minutes later, after they had made the detour suggested by the professor, realized to their joy that they had passed the dangerous abyss in safety.
"And now," shouted Frank, "forward for the Viking ship or—"
"Or a sell!" shouted the irrepressible Billy.
"Or a sell," echoed Frank.