midnight
The way was rough , and before he was half way past the falls , Frank began to fear he could not make it . But he kept on , and half an hour later he floated the canoe into the quiet waters at the foot of the waterfall . Then he began paddling again . It was past midnight when the stream , which had now become a little river , took a sudden turn . As he rounded it Frank uttered a half-suppressed exclamation . There ahead of him , perched on the cliff , at the foot of which the river flowed , was the sanitarium . `` That 's what I wanted to know , '' he said , as he steered the canoe over toward the cliff .