"Listen!" he whispered. "I hear voices."
Bob listened. Captain Sumner was right. From the cavern came the sounds of several human tongues.
"They are not speaking Russian," said the captain. "Perhaps we have stumbled upon more savages."
Hardly had he spoken when three human beings came into view.
They were bundled up in furs, in strong contrast to the other natives, who had scarcely any body-covering.
The new-comers were jabbering among themselves at a great rate.
Presently they came to a halt before a large slab of ice.
They tugged and pounded on this until the slab fell to one side, revealing a strange-looking opening.
"What are they up to now?" whispered Bob.
"I don't know—wait."
They waited. Presently the three men disappeared within the opening. Soon a smoke came out, and they saw that firebrands had been lit to light up the scene.