While they watched, admiring the swelling, swinging, ponderous advance of the great surface, and harkening to the booming thunder of its agony that filled the air, a breathless runner joined the group and spoke a few quick words to Black Feather. That chief approached Ouenwa and whispered in his ear. The boy glanced quickly at Beatrix and Kingswell, and then questioned Black Feather anxiously. Presently he turned back to the lovers.
"The ice is stuck down-stream," he said. "Blue Cloud has seen it. He fears that the water will rise over the flat—and the fort."
The river continued to rise until evening. After that the waters subsided a little, great cakes of rotten ice hung stranded along the crest of the bank, and the main body ceased to run downward. But from up the valley the thunder of a hidden disturbance still boomed across the windless air.
"The jam had broken down-stream," said Ouenwa.
Kingswell, unused to the ways of running ice, was satisfied, and retired to his couch with an easy mind. He slept soundly until, in the gray of the dawn, Ouenwa shook him roughly, and all but dragged him to the floor.
"Wake up, wake up," cried the boy. "Damn, but you sleep like a bear! The fort is in danger! We must run for higher land."
"Rip me!" exclaimed Kingswell, springing to his feet, "but what is the trouble? Are we attacked?"
"The river is all but empty of water," replied Ouenwa. "The ice sags in the channel, like an empty garment. The water hangs above, behind the third point where we cut the timber for the boats."
Kingswell, all the while, was busily employed pulling on his heavy clothes. Though he did not fully understand the threatening danger, he felt that it was real enough. While he tied the thongs of his deerhide leggins, Ouenwa told him that warning had reached the fort but a few minutes before.
"How?" inquired Kingswell, hurriedly bestowing a wallet of gold coins and some other valuables about his person.