We must tell Willy what we suspect and assign him to guard duty.

An Indian can sleep and yet be on watch." "Like Hindenburg, who always sleeps with one ear awake," suggested Hippy.
"But never hears anything with it," laughed Tom.

"We'll see." Later in the day when Tom spoke confidentially with the Indian about what the Overlanders suspected, Willy evinced no surprise.

He nodded in agreement with Tom that the new dam must be guarded.
It was.

Willy slept near it in a lean-to down near the river.