"Good-bye, Buffalo!" exclaimed Billy, as he patted the faithful steed. "I hate to leave you, old fellow, but it's got to be. Maybe you can swim ashore."
Buffalo whinnied and stretched out his velvety nose for a caress. There were tears in Billy's eyes, and those of Frank and Andy were not altogether free from moisture, for they had grown to care very much for the animals they had ridden over the prairies.
A half hour passed. Frank, who had been looking at the water from time to time, suddenly uttered an exclamation.
"What is it?" asked his brother. "Do you see anything?"
"Yes!" cried Frank. "I see that the water hasn't risen an inch in the last half hour. Before that it was going up at the rate of nearly a foot an hour."
"Are you sure?" cried Andy.
"I certainly am. I've been watching that yellow rock there, wondering when it would be covered, but the water has been lapping at the base of it more than thirty minutes."
"What does that mean?" asked Andy, anxiously.
"That the lake has stopped rising," said Frank quickly. "Either it has reached its limit, or they have suspected something wrong at the dam, and opened the gates."
"It hasn't reached its limit," declared Billy, "for when it does this hill will be covered. It's away below the top of the dam."