A slip, a fall, would have meant that Bo must drown in that mountain torrent.
Ranger trotted straight to the edge, and there, obedient to Helen's clutch on the bridle, he halted.

The stream was fifty feet wide, shallow on the near side, deep on the opposite, with fast current and big waves.
Helen was simply too frightened to follow.
"Let him come!" yelled Dale.

"Stick on now!...

Ranger!" The big black plunged in, making the water fly.

That stream was nothing for him, though it seemed impassable to Helen.