“Thank goodness that something connects with something,” said I. “At present we seem to be faced by a long series of inexplicable incidents with no bearing upon each other. For example, what possible connection can there be between an angry wolfhound and a visit to Bohemia, or either of them with a man crawling down a passage at night? As to your dates, that is the biggest mystification of all.”

Holmes smiled and rubbed his hands. We were, I may say, seated in the old sitting-room of the ancient hotel, with a bottle of the famous vintage of which Holmes had spoken on the table between us.

“Well, now, let us take the dates first,” said he, his fingertips together and his manner as if he were addressing a class. “This excellent young man’s diary shows that there was trouble upon July 2nd, and from then onward it seems to have been at nine-day intervals, with, so far as I remember, only one exception. Thus the last outbreak upon Friday was on September 3rd, which also falls into the series, as did August 26th, which preceded it. The thing is beyond coincidence.”