our present case, for instance. Without the thumb-print, the robbery might have been committed by anybody; there is no clue whatever. But the existence of the thumb-print narrows the inquiry down to Reuben or some person having access to his finger-prints."
"Yes, I see. Then you consider my theory of John Hornby as the perpetrator of the robbery as quite a tenable one?"
"Quite," replied Thorndyke. "I have entertained it from the first; and the new facts that you have gathered increase its probability. You remember I said that four hypotheses were possible: that the robbery was committed either by Reuben, by Walter, by John Hornby, or by some other person. Now, putting aside the 'some other person' for consideration only if the first three hypotheses fail, we have left, Reuben, Walter, and John. But if we leave the thumb-print out of the question, the probabilities evidently point to John Hornby, since he, admittedly, had access to the diamonds, whereas there is nothing to show that the others had. The thumb-print, however, transfers the suspicion to Reuben; but yet, as your theory makes evident, it does not completely clear John Hornby. As the case stands, the balance of probabilities may be stated thus: John Hornby undoubtedly had access to the diamonds, and therefore might have stolen them. But if the thumb-mark was made after he closed the safe and before he opened it again, some other person must have had access to them, and was probably the thief.
"The thumb-mark is that of Reuben Hornby, a fact that establishes a prima facie probability that he stole the diamonds. But there is no evidence that he had access to them, and if he had not, he could not have made the thumb-mark in the manner and at the time stated.
"But John Hornby may have had access to the previously-made thumb-mark of Reuben, and may possibly have obtained it; in which case he is almost certainly the thief.
"As to Walter Hornby, he may have had the means of obtaining Reuben's thumb-mark; but there is no evidence that he had access either to the diamonds or to Mr. Hornby's memorandum block. The prima facie probabilities in his case, therefore, are very slight."
"The actual points at issue, then," I said, "are, whether Reuben had any means of opening the safe, and whether Mr. Hornby ever did actually have the opportunity of obtaining Reuben's thumb-mark in blood on his memorandum block."
"Yes," replied Thorndyke. "Those are the points—with some others—and they are likely to remain unsettled. Reuben's rooms have been searched by the police, who failed to find any skeleton or duplicate keys; but this proves nothing, as he would probably have made away with them when he heard of the thumb-mark being found. As to the other matter, I have asked Reuben, and he has no recollection of ever having made a thumb-mark in blood. So there the matter rests."
"And what about Mr. Hornby's liability for the diamonds?"
"I think we may dismiss that," answered Thorndyke. "He had undertaken no liability and there was no negligence. He would not be liable at law."
After my colleague retired, which he did quite early, I sat for a long time pondering upon this singular case in which I found myself involved. And the more I thought about it the more puzzled I became. If Thorndyke had no more satisfactory explanation to offer than that which he had given me this evening, the defence was hopeless, for the court was not likely to accept his estimate of the evidential value of finger-prints. Yet he had given Reuben something like a positive assurance that there would be an adequate defence, and had expressed his own positive conviction of the accused man's innocence. But Thorndyke was not a man to reach such a conviction through merely sentimental considerations. The inevitable conclusion was that he had something up his sleeve—that he had gained possession of some facts that had escaped my observation; and when I had reached this point I knocked out my pipe and betook myself to bed.
The Prisoner
On the following morning, as I emerged from my room, I met Polton coming up with a tray (our bedrooms were on the attic floor above the laboratory and workshop), and I accordingly followed him into my friend's chamber.
"I shan't go out to-day," said Thorndyke, "though I shall come down presently. It is very inconvenient, but one must accept the inevitable. I have had a knock on the head, and, although I feel none the worse, I must take the proper precautions—rest and a low diet—until I see that no results are going to follow. You can attend to the scalp wound and send round the necessary letters, can't you?"
I expressed my willingness to do all that was required and applauded my friend's self-control and good sense; indeed, I could not help contrasting the conduct of this busy, indefatigable man, cheerfully resigning himself to most distasteful inaction, with the fussy behaviour of the ordinary patient who, with nothing of importance to do, can hardly be prevailed upon to rest, no matter how urgent the necessity. Accordingly, I breakfasted alone, and spent the morning in writing and despatching letters to the various persons who were expecting visits from my colleague.
Shortly after lunch (a very spare one, by the way, for Polton appeared to include me in the scheme of reduced diet) my expectant ear caught the tinkle of a hansom approaching down Crown Office Row.
"Here comes your fair companion," said Thorndyke, whom I had acquainted with my arrangements, "Tell Hornby, from me, to keep up his courage, and, for yourself, bear my warning in mind. I should be sorry indeed if you ever had cause to regret that you had rendered me the very valuable services for which I am now indebted to you. Good-bye; don't keep her waiting."
I ran down the stairs and came out of the entry just as the cabman had pulled up and flung open the doors.
"Holloway Prison—main entrance," I said, as I stepped up on to the footboard.
"There ain't no back door there, sir," the man responded, with a grin; and I was glad that neither the answer nor the grin was conveyed to my fellow-passenger.
"You are very punctual, Miss Gibson," I said. "It is not half-past one yet."
"Yes; I thought I should like to get there by two, so as to have as long a time with him as is possible without shortening your interview."
I looked at my companion critically. She was dressed with rather more than her usual care, and looked, in fact, a very fine lady indeed. This circumstance, which I noted at first with surprise and then with decided approbation, caused me some inward discomfort, for I had in my mind a very distinct and highly disagreeable picture of the visiting arrangements at a local prison in one of the provinces, at which I had acted temporarily as medical officer.
"I suppose," I said at length, "it is of no use for me to re-open the question of the advisability of this visit on your part?"
"Not the least," she replied resolutely, "though I understand and appreciate your motive in wishing to do so."
"Then," said I, "if you are really decided, it will be as well for me to prepare you for the ordeal. I am afraid it will give you a terrible shock."
"Indeed?" said she. "Is it so bad? Tell me what it will be like."
"In the first place," I replied, "you must keep in your mind the purpose of a prison like Holloway. We are going to see an innocent man—a cultivated and honourable gentleman. But the ordinary inmates of Holloway are not innocent men; for the most part, the remand cases on the male side are professional criminals, while the women are either petty offenders or chronic inebriates. Most of them are regular customers at the prison—such is the idiotic state of the law—who come into the reception-room like travellers entering a familiar hostelry, address the prison officers by name and demand the usual privileges and extra comforts—the 'drunks,' for instance, generally ask for a dose of bromide to steady their nerves and a light in the cell to keep away the horrors. And such being the character of the inmates, their friends who visit them are naturally of the same type—the lowest outpourings of the slums; and it is not surprising to find that the arrangements of the prison are made to fit its ordinary inmates. The innocent man is a negligible quantity, and no arrangements are made for him or his visitors."
"But