“What do you think, Dr. Trendon?” he asked.

More explicit inquiry was not necessary.

The surgeon understood what was in his superior’s mind.

“Never can tell about volcanoes, sir,” he said.

“Of course,” agreed the captain.  “But—­well, do you recognise any of the symptoms?”

“Want me to diagnose a case of earthquake, sir?” grinned Trendon.  “She might go off to-day, or she might behave herself for a century.”

“Well, it’s all chance,” said the other, cheerfully.  “The man might be alive.  At any rate we must do our best on that theory.  What do you make of that cloud on the peak?”

“Poisonous vapours, I suppose.  Thought we’d have a chance to make sure just now.  Seemed to be coming right for us.  Wind’s shifted it since.”

“There couldn’t be anything alive up there?”

“Not so much as a bug,” replied the doctor positively.

“Yet I thought when the vapour lifted a bit that I saw something moving.”

“When was that, sir?”

“Ten or fifteen minutes back.”

“We’ll see soon enough, sir,” put in Forsythe.  “The wind is driving it down to the south’ard.”

Sullenly, reluctantly, the forbidding mass moved across the headland.  All glasses were bent upon it.  Without taking his binocular from his eyes, Trendon began to ruminate aloud.

“If he could have got to the beach....  No vapour there....  Signal, though....  Perhaps he hadn’t time....  And I’d hate to risk good men on that hell’s cauldron....  Just as much risk here, perhaps.  Only it seems—­”

“There it is,” cried Forsythe.  “Look.  The highest point.”

Dull, gray wisps of murk, the afterguard of the gaseous cloud, were twisting and spiraling in a witch-dance across the landscape, and, seen by snatches and glimpses through it, something flapped darkly in the breeze.  Suddenly the veil parted and fled.  A flag stood forth in the sharp gust, rigid, and appalling.  It was black.

“The Jolly Roger, by God!  They’ve come back!” exclaimed Forsythe.

“And set up the sign of their shop,” added Barnett.

“If they stuck to their flag—­good-bye,” observed Trendon grimly.

“Dr. Trendon,” said Captain Parkinson, “you will arm yourself and go with me in the gig to make a landing.”

“Yes, sir,” responded the surgeon.

“Mr. Barnett.”

“Yes, sir.”

“Should we be overtaken by the vapour while on the highland and be unable to get back to the beach, you are to send no rescuing party up there until the air has cleared.”

“But, sir, may we not—­”

“Do you understand?”

“Yes, sir.”

“In case of an attack you will at once send in another boat with a howitzer.”

“Yes, sir.”

“Dr. Trendon, will you see Mr. Slade and inquire of him the best point for landing?”

Trendon hesitated.