On the return to the wharf, Sir Walter somewhat nervously asked Holmes if he thought the plan they had settled upon would work. "Charon is a very shrewd old fellow," said he. "He may outwit us yet." "The chances are just two and one-eighth degrees in your favor," observed Holmes, quietly, with a glance at Raleigh's ears. "The temporal angle of your ears is 93-1/8 degrees, whereas Charon's stand out at 91, by my otometer. To that extent your criminal instincts are superior to his. If criminology is an exact science, reasoning by your respective ears, you ought to beat him out by a perceptible though possibly narrow margin." With which assurance Raleigh went ahead with his preparations, and within twelve hours the _Gehenna_ was under way, carrying a full complement of crew and officers, with every state-room on board occupied by some spirit of the more illustrious kind. Even Shylock was on board, though no one knew it, for in the dead of night he had stolen quietly up the gang-plank and had hidden himself in an empty water-cask in the forecastle. [Illustration: "IN THE DEAD OF NIGHT SHYLOCK HAD STOLEN UP THE GANG-PLANK"] "'Tisn't Venice," he said, as he sat down and breathed heavily through the bung of the barrel, "but it's musty and damp enough, and, considering the cost, I can't complain. You can't get something for nothing, even in Hades." VIII ON BOARD THE "GEHENNA" When the _Gehenna_ had passed down the Styx and out through the beautiful Cimmerian Harbor into the broad waters of the ocean, and everything was comparatively safe for a while at least, Sherlock Holmes came down from the bridge, where he had taken his place as the commander of the expedition at the moment of departure. His brow was furrowed with anxiety, and through his massive forehead his brain could be seen to be throbbing violently, and the corrugations of his gray matter were not pleasant to witness as he tried vainly to squeeze an idea out of them. "What is the matter?" asked Demosthenes, anxiously. "We are not in any danger, are we?" "No," replied Holmes. "But I am somewhat puzzled at the bubbles on the surface of the ocean, and the ripples which we passed over an hour or two ago, barely perceptible through the most powerful microscope, indicate to my mind that for some reason at present unknown to me the House-boat has changed her course. Take that bubble floating by. It is the last expiring bit of aerial agitation of the House-boat's wake. Observe whence it comes. Not from the Azores quarter, but as if instead of steering a straight course thither the House-boat had taken a sharp turn to the northeast, and was making for Havre; or, in other words, Paris instead of London seems to have become their destination." Demosthenes looked at Holmes with blank amazement, and, to keep from stammering out the exclamation of wonder that rose to his lips, he opened his _bonbonniere_ and swallowed a pebble.