“That man yonder,” he spoke, “the one in black.  Watch him.”  Then he told his story.  The detective laughed and walked forward.

It was a most fortunate incident.  It was a strange case.  That mere act of the cigar clerk placed the police on the track and gave to the world the only clue that it holds of the Blind Spot.

The detective had laughed at the lad’s recital—­almost any one had a patent for being queer—­and if this gentleman had a whim for a certain brand of humour that was his business.  Nevertheless, he would stroll forward.

The man was not hard to distinguish; he was standing on the forward deck facing the wind and peering through the mist at the grey, heavy heave of the water.  Alongside of them the dim shadow of a sister ferry screamed its way through the fogbank.  That he was a landsman was evidenced by his way of standing; he was uncertain; at every heave of the boat he would shift sidewise.  An unusually heavy roll caught him slightly off-balance and jostled him against the detective.  The latter held up his hand and caught him by the arm.

“A bad morning,” spoke the officer.  “B-r-r-r!  Did you notice the Yerbe Buena yonder?  She just grazed us.  A bad morning.”

The stranger turned.  As the detective caught the splendid face, the glowing eyes and the youthful smile, he started much as had done the cigar clerk.  The same effect of the age melting into youth and—­the officer being much more accustomed to reading men—­ a queer sense of latent and potent vision.  The eyes were soft and receptive but for all that of the delicate strength and colour that comes from abnormal intellect.  He noted the pupils, black, glowing, of great size, almost filling the iris and the whole melting into intensity that verged into red.  Either the man had been long without sleep or he was one of unusual intelligence and vitality.

“A nasty morning,” repeated the officer.

“Ah!  Er, yes—­did you say it was a nasty morning?  Indeed, I do not know, sir.  However, it is very interesting.”

“Stranger in San Francisco?”

“Well, yes.  At least, I have never seen it.”

“H-m!” The detective was a bit nonplussed by the man’s evident evasion.  “Well, if you are a stranger I suppose it is up to me to come to the defence of my city.  This is one of Frisco’s fogs.  We have them occasionally.  Sometimes they last for days.  This one is a low one.  It will lift presently.  Then you will see the sun.  Have you ever seen Frisco’s sun?”

“My dear sir”—­this same slow articulation—­“I have never seen your sun nor any other.”

“Hum!”

It was an answer altogether unexpected.  Again the officer found himself gazing into the strange, refined face and wonderful eyes.  The man was not blind, of that he was certain.  Neither was his voice harsh or testy.  Rather was it soft and polite, of one merely stating a fact.  Yet how could it be?  He remembered the cigar clerk.  Neither cigar nor sun!  From what manner of land could the man come?  A detective has a certain gift of intuition.  Though on the face of it, outside of the man’s personality, there could be nothing to it but a joke, he chose to act upon the impulse.  He pulled back the door which had been closed behind them and re-entered the boat.  When he returned the boat had arrived at the pier.