The case was remarkable in other respects also; first, because in one of its features it had a resemblance to the case of Samuel's diamonds, which first brought the Red Triangle to Hewitt's notice; next, because in its course Hewitt encountered what he declared to be the most ingenious and baffling cryptogram that he had ever seen in the length of his strange experience; and thirdly, because I was the means of placing that cryptogram in his hands, owing to one of those odd chances that arise again and again in real life--are, indeed, so common as to pass almost unregarded--and yet might be thought improbable if offered in the guise of a mere story. Hewitt has often alluded to the curious persistence of such chances in his experience. I think I have elsewhere mentioned a certain police officer's prolonged search after a criminal for whose arrest he held a warrant, ending in the discovery--because of a misdirected call--that the man had been living all the time next door to himself; and I have also told of the other detective inspector, who, being sent in search of a criminal of whom he had but the meagrest and most unsatisfactory particulars, and whom he scarcely hoped ever to run down, actually _fell over_ the man as he was leaving the office where he had received his information, in the doorway of which the fellow had stooped to tie his shoe-lace! But, as Hewitt would say, nothing but the exceptional nature of the surrounding circumstances makes these things seem extraordinary. What more ordinary experience, for example, than to meet a friend in some London street--perhaps one friend of the only dozen or so you have among the four millions of people about you? The odds against you two, of all the millions, choosing the one street of the thousands in London to walk down at the same minute of time, would seem incalculable; and yet the chance comes off so often as to be a matter of the most ordinary experience. On this occasion I was expecting orders from my editor to produce certain articles on the subject of the London hospitals. It will be remembered that the matter was very much in the air a few years ago, and as nothing is professionally more uncomfortable than to be called on suddenly for an accurate and reasonable leading article on a subject one knows nothing about, I wrote to my friend, Barton McCarthy, who is house-surgeon at St. Augustine's, and he replied by an offer to tell me anything I cared to ask if I would call at the hospital. I set out accordingly some little time after a breakfast even later than ordinary, and called in at Hewitt's office on my way downstairs, to say that I should not be lunching at our usual place that day. "No," Hewitt answered, "nor shall I, I expect. I'm off to the City, at once. I have an urgent message to go immediately to Kingsley, Bell and Dalton's, in Broad Street, where a big bond robbery has just been discovered. Perhaps I can give you a lift in my cab?"