"Ask him what it is," called Tad.
"He says he doesn't know," answered the Professor.
Tad halted his pony and turned in the saddle waiting until Ned came up with him.
"What is it, Ned?" he demanded.
"Don't you hear that noise?"
"That roaring?" asked Butler.
"Yes."
"I've been listening to that for the last sixty seconds," answered Tad, his face drawing down into sharp lines of concentration. "What do you think it is?"
"Water."
"It's something more than mere water. It's a torrent, Ned. This is where we get it. Everyone crowd close to the bank," shouted Tad.