“I’m forced to go full speed ahead to cross the bar,” he told Quest.  “I’m sorry, but the tide’s just on the turn.”

They looked at one another a little blankly.

The Professor, however, beamed upon them all.

“I have always understood,” he said, “that Port Said is a most interesting place.”

CHAPTER XI

THE SHIP OF HORROR

Quest leaned a little forward and gazed down the line of steamer chairs.  The Professor, in a borrowed overcoat and cap, was reclining at full length, studying a book on seagulls which he had found in the library.  Laura and Lenora were both dozing tranquilly.  Mr. Harris of Scotland Yard was deep in a volume of detective stories.

“As a pleasure cruise,” Quest remarked grimly, “this little excursion seems to be a complete success.”

Laura opened her eyes at once.

“Trying to get my goat again, eh?” she retorted.  “I suppose that’s what you’re after.  Going to tell me, I suppose, that it wasn’t Craig I saw board this steamer?”

“We are all liable to make mistakes,” Quest observed, “and I am inclined to believe that this is one of yours.”

Laura’s expression was a little dogged.

“If he’s too clever for you and Mr. Harris,” she said, “I can’t help that.  I only know that he came on board.  My eyes are the one thing in life I do believe.”

“If you’ll excuse my saying so, Miss Laura,” Harris ventured, leaning deferentially towards her, “there isn’t a passenger on board this ship, or a servant, or one of the crew, whom we haven’t seen.  We’ve been into every stateroom, and we’ve even searched the hold.  We’ve been over the ship, backwards and forwards.  The Captain’s own steward has been our guide, and we’ve conducted an extra search on our own account.  Personally, I must say I have come to the same conclusion as Mr. Quest.  At the present moment there is no such person as the man we are looking for, on board this steamer.”

“Then he either changed on to another one,” Laura declared obstinately, “or else he jumped overboard.”

Harris, who was a very polite man, gazed thoughtfully seaward.  Quest smiled.

“When Laura’s set on a thing,” he remarked, “she takes a little moving.  What do you think about it, Professor?”

The Professor laid down his book, keeping his finger in the place.  He had the air of a man perfectly content with himself and his surroundings.

“My friend,” he said, “I boarded this steamer with only one thought in my mind—­Craig.  At the present moment, I feel myself compelled to plead guilty to a complete change of outlook.  The horrors of the last few months seem to have passed from my brain like a dream.  I lie here, I watch these white-winged birds wheeling around us, I watch the sunshine make jewels of the spray, I breathe this wonderful air, I relax my body to the slow, soothing