By degrees the trees got dimmer, but the water shone with a pale gleam and presently the moon came out between drifting clouds.
Then as they swept round a bend a throbbing Agatha had heard for some time got suddenly loud and she glanced at Thirlwell.
"The Grand Rapid," he said.

"The water's very low; it's quite safe." Agatha knew he did not think she was afraid; he had tactfully pretended to misunderstand her glance, and she fixed her eyes ahead.

The shadows were deeper and the forest was indistinct, but it was not dark.

Besides, the moon was getting bright and threw a glittering beam across the river.

She could see for some distance and not far in front the water was furrowed and marked by lines of foam.