Yes, I know now.

Why, it is all firm about here, and nobody could be bogged unless he got into a hole.

Ahoy!" He shouted once more, but there was no answer; and when he raised his voice again it was only for the sound to seem to come back, just as if they were shut up in some large room.
"He must be hereabout," said Dick.
"Shall we find our way back to the boat ?" said Tom in a doubting tone.
"I don't know, but if we don't we could walk home in half an hour.

Come along.

Ahoy!" Still no answer; and in spite of his companion's suggestions and strange doubts Dick kept on hunting about in the darkness among the patches of alders and the heath that here grew freely.