“I say,” asked Walker, “isn’t it rather dangerous to go slumming about West Africa alone?”

Hatteras did not reply for a moment.  He seemed not to have heard the suggestion, and when he did speak it was to ask a quite irrelevant question.

“Have you ever seen the Horse Guards’ Parade on a dark, rainy night?” he asked; but he never moved his head, he never took his eyes from the forest.  “The wet level of ground looks just like a lagoon and the arches a Venice palace above it.”

“But look here, Dick!” said Walker, keeping to his subject.  “You never leave word when you are coming back.  One never knows that you have come back until you show yourself the morning after.”

“I think,” said Hatteras slowly, “that the finest sight in the world is to be seen from the bridge in St. James’s Park when there’s a State ball on at Buckingham Palace and the light from the windows reddens the lake and the carriages glance about the Mall like fireflies.”

“Even your servants don’t know when you come back,” said Walker.

“Oh,” said Hatteras quietly, “so you have been asking questions of my servants?”

“I had a good reason,” replied Walker, “your safety,” and with that the conversation dropped.

Walker watched Hatteras.  Hatteras watched the forest.  A West African mangrove forest at night is full of the eeriest, queerest sounds that ever a man’s ears harkened to.  And the sounds come not so much from the birds, or the soughing of the branches; they seem to come from the swamp life underneath the branches, at the roots of trees.  There’s a ceaseless stir as of a myriad of reptiles creeping in the slime.  Listen long enough and you will fancy that you hear the whirr and rush of innumerable crabs, the flapping of innumerable fish.  Now and again a more distinctive sound emerges from the rest—­the croaking of a bull-frog, the whining cough of a crocodile.  At such sounds Hatteras would start up in his chair and cock his head like a dog in a room that hears another dog barking in the street.

“Doesn’t it sound damned wicked?” he said, with a queer smile of enjoyment.

Walker did not answer.  The light from a lamp in the room behind them struck obliquely upon Hatteras’ face and slanted off from it in a narrowing column until it vanished in a yellow thread among the leaves of the trees.  It showed that the same enjoyment which ran in Hatteras’ voice was alive upon his face.  His eyes, his ears, were alert, and he gently opened and shut his mouth with a little clicking of the teeth.  In some horrible way he seemed to have something in common with, he appeared almost to participate in, the activity of the swamp.  Thus, had Walker often seen him sit, but never with the light so clear upon his face, and the sight gave to him a quite new impression of his friend.  He wondered whether all these months his judgment had been wrong.  And out of that wonder a new thought sprang into his mind.