"I heard that whistle too," he said.

"But it was a mountain-boy." He was right.

At a curve in the road, they met a young Swiss lad who went by them with a smile and salute, and fell to whistling again when he had passed.
Isabel pressed on in silence.

She had started in feverish haste, but her speed was gradually slackening.

She looked neither to right nor left; her eyes perpetually strained forward as though they sought for something just beyond their range of vision.