“But what is it, then?”
“Look closely.”
They went to the edge of the beach and looked up and down the river carefully, also studying the forking valleys into which they could see from the place where they were in camp.
“Well, I don’t know,” said Rob, “but it seems to me she’s rising a little!”
Alex nodded. “We’ve been in camp here three hours now,” said he, “and she’s come up a little more than an inch.”
“Why, how do you know that?” asked John.
“I set a stick with a notch at water-level when we first came ashore.”
“How did you happen to think of that?”
“Very likely the same thing which made Rob guess it.”