What was the gentleman that wanted to buy a steamer in Nassau doing up the Hudson?
This was the principal one: he could not answer it.

He gave it up; as the French have it, he had to "throw his tongue to the dogs," having no use for it in this connection.
But while he was dreaming of the possible mission of the stranger, he heard voices on the beach.

Not deeming it wise to show himself, he rolled off the cushion upon the floor of the standing-room, and then fixed himself in a position where he could see and hear what passed between the speakers.

He could see without being seen.

It did not require a second look for him to decide that the second person on the beach was Major Pierson, though his companion called him Mulgate.
If Christy had been interested before, he was excited now.