of. It proves, then, that the bubble is a portion of the wake of a
Stygian craft, and the only Stygian craft that has cleared the
Cimmerian Harbor for years is the House-boat--Q. E. D."

"We can go back until we find the ripple again, and follow that, I
presume," sneered Le Coq, who did not take much stock in the theories
of his great rival, largely because he was a detective by intuition
rather than by study of the science.

"You can if you want to, but it is better not to," rejoined Holmes,
simply, as though not observing the sneer, "because the ripple
represents the outer lines of the angle of disturbance in the water;
and as any one of the sides to an angle is greater than the
perpendicular from the hypothenuse to the apex, you'd merely be going
the long way. This is especially important when you consider the
formation of the bow of the House-boat, which is rounded like the
stern of most vessels, and comes near to making a pair of ripples at
an angle of ninety degrees."

"Then," observed Sir Walter, with a sigh of disappointment, "we must
change our course and sail for Paris?"

"I am afraid so," said Holmes; "but of course it's by no means
certain as yet. I think if Columbus would go up into the mizzentop
and look about him, he might discover something either in
confirmation or refutation of the theory."

"He couldn't discover anything," put in Pinzon. "He never did."

"Well, I like that!" retorted Columbus. "I'd like to know who