During our walk home my friend was unusually thoughtful and silent, and his face bore a look of concentration under which I thought I could detect, in spite of his habitually impassive expression, a certain suppressed excitement of a not entirely unpleasurable kind. I forbore, however, from making any remarks or asking questions, not only because I saw that he was preoccupied, but also because, from my knowledge of the man, I judged that he would consider it his duty to keep his own counsel and to make no unnecessary confidences even to me.  
On our arrival at his chambers he immediately handed over the camera to Polton with a few curt directions as to the development of the plates, and, lunch being already prepared, we sat down at the table without delay.
 
We had proceeded with our meal in silence for some time when Thorndyke suddenly laid down his knife and fork and looked into my face with a smile of quiet amusement.
 
"It has just been borne in upon me, Jervis," said he, "that you are the most companionable fellow in the world. You have the heaven-sent gift of silence."
 
"If silence is the test of companionability," I answered, with a grin, "I think I can pay you a similar compliment in even more emphatic terms."
 
He laughed cheerfully and rejoined—
 
"You are pleased to be sarcastic, I observe; but I maintain my position. The capacity to preserve an opportune silence is the rarest and most precious of social accomplishments. Now, most men would have plied me with questions and babbled comments on my proceedings at Scotland Yard, whereas you have allowed me to sort out, without interruption, a mass of evidence while it is still fresh and impressive, to docket each item and stow it away in the pigeonholes of my brain. By the way, I have made a ridiculous oversight."
 
"What is that?" I asked.
 
"The 'Thumbograph.' I never ascertained whether the police have it or whether it is still in the possession of Mrs. Hornby."
 
"Does it matter?" I inquired.
 
"Not much; only I must see it. And perhaps it will furnish an excellent pretext for you to call on Miss Gibson. As I am busy at the hospital this afternoon and Polton has his hands full, it would be a good plan for you to drop in at Endsley Gardens—that is the address, I think—and if you can see Miss Gibson, try to get a confidential chat with her, and extend your knowledge of the manners and customs of the three Messieurs Hornby. Put on your best bedside manner and keep your weather eye lifting. Find out everything you can as to the characters and habits of those three gentlemen, regardless of all scruples of delicacy. Everything is of importance to us, even to the names of their tailors."
 
"And with regard to the 'Thumbograph'?"
 
"Find out who has it, and, if it is still in Mrs. Hornby's possession, get her to lend it to us or—what might, perhaps, be better—get her permission to take a photograph of it."
 
"It shall be done according to your word," said I. "I will furbish up my exterior, and this very afternoon make my first appearance in the character of Paul Pry."
 
About an hour later I found myself upon the doorstep of Mr. Hornby's house in Endsley Gardens listening to the jangling of the bell that I had just set in motion.
 
"Miss Gibson, sir?" repeated the parlourmaid in response to my question. "She was going out, but I am not sure whether she has gone yet. If you will step in, I will go and see."
 
I followed her into the drawing-room, and, threading my way amongst the litter of small tables and miscellaneous furniture by which ladies nowadays convert their special domain into the semblance of a broker's shop, let go my anchor in the vicinity of the fireplace to await the parlourmaid's report.
 
I had not long to wait, for in less than a minute Miss Gibson herself entered the room. She wore her hat and gloves, and I congratulated myself on my timely arrival.
 
"I didn't expect to see you again so soon, Dr. Jervis," she said, holding out her hand with a frank and friendly manner, "but you are very welcome all the same. You have come to tell me something?"
 
"On the contrary," I replied, "I have come to ask you something."
 
"Well, that is better than nothing," she said, with a shade of disappointment. "Won't you sit down?"
 
I seated myself with caution on a dwarf chair of scrofulous aspect, and opened my business without preamble.
 
"Do you remember a thing called a 'Thumbograph'?"
 
"Indeed I do," she replied with energy. "It was the cause of all this trouble."
 
"Do you know if the police took possession of it?"
 
"The detective took it to Scotland Yard that the finger-print experts might examine it and compare the two thumb-prints; and they wanted to keep it, but Mrs. Hornby was so distressed at the idea of its being used in evidence that they let her have it back. You see, they really had no further need of it, as they could take a print for themselves when they had Reuben in custody; in fact, he volunteered to have a print taken at once, as soon as he was arrested, and that was done."
 
"So the 'Thumbograph' is now in Mrs. Hornby's possession?"
 
"Yes, unless she has destroyed it. She spoke of doing so."
 
"I hope she has not," said I, in some alarm, "for Dr. Thorndyke is extremely anxious, for some reason, to examine it."
 
"Well, she will be down in a few minutes, and then we shall know. I told her you were here. Have you any idea what Dr. Thorndyke's reason is for wanting to see it?"
 
"None whatever," I replied. "Dr. Thorndyke is as close as an oyster. He treats me as he treats every one else—he listens attentively, observes closely, and says nothing."
 
"It doesn't sound very agreeable," mused Miss Gibson; "and yet he seemed very nice and sympathetic."
 
"He is very nice and sympathetic," I retorted with some emphasis, "but he doesn't make himself agreeable by divulging his clients' secrets."
 
"I suppose not; and I regard myself as very effectively snubbed," said she, smiling, but evidently somewhat piqued by my not very tactful observation.
 
I was hastening to repair my error with apologies and self-accusations, when the door opened and an elderly lady entered the room. She was somewhat stout, amiable and placid of mien, and impressed me (to be entirely truthful) as looking rather foolish.
 
"Here is Mrs. Hornby," said Miss Gibson, presenting me to her hostess; and she continued, "Dr. Jervis has come to ask about the 'Thumbograph.' You haven't destroyed it, I hope?"
 
"No, my dear," replied Mrs. Hornby. "I have it in my little bureau. What did Dr. Jervis wish to know about it?"
 
Seeing that she was terrified lest some new and dreadful surprise should be sprung upon her, I hastened to reassure her.
 
"My colleague, Dr. Thorndyke, is anxious to examine it. He is directing your nephew's defence, you know."
 
"Yes, yes," said Mrs. Hornby. "Juliet told me about him. She says he is a dear. Do you agree with her?"
 
Here I caught Miss Gibson's eye, in which was a mischievous twinkle, and noted a little deeper pink in her cheeks.
 
"Well," I answered dubiously, "I have never considered my colleague in the capacity of a dear, but I have a very high opinion of him in every respect."
 
"That, no doubt, is the masculine equivalent," said Miss Gibson, recovering from the momentary embarrassment that Mrs. Hornby's artless repetition of her phrase had produced. "I think the feminine expression is more epigrammatic and comprehensive. But to return to the object of Dr. Jervis's visit. Would you let him have the 'Thumbograph,' aunt, to show to Dr. Thorndyke?"
 
"Oh, my dear Juliet," replied Mrs. Hornby, "I would do anything—anything—to help our poor boy. I will never believe that he could be guilty of theft—common, vulgar theft. There has been some dreadful mistake—I am convinced there has—I told the detectives so. I assured them that Reuben could not have committed the robbery, and that they were totally mistaken in supposing him to be capable of such an action. But they would not listen to me, although I have known him since he was a little child, and ought to be able to judge, if anyone is. Diamonds, too! Now, I ask you, what could Reuben want with diamonds? and they were not even cut."
 
Here Mrs. Hornby drew forth a lace-edged handkerchief and mopped her eyes.
 
"I am sure Dr. Thorndyke will be very much interested to see this little book of yours," said I, with a view to stemming the tide of her reflections.
 
"Oh, the 'Thumbograph,'" she replied. "Yes, I will let him have it with the greatest pleasure. I am so glad he wishes to see it; it makes one feel hopeful to know that he is taking so much interest in the case. Would you believe it, Dr. Jervis, those detective people actually wanted to keep it to bring up in evidence against the poor boy. My 'Thumbograph,' mind you. But I put my foot down there and they had to return it. I was resolved that they should not receive any assistance from me in their efforts to involve my nephew in this horrible affair."
 
"Then, perhaps," said Miss Gibson, "you might give Dr. Jervis the 'Thumbograph' and he can hand it to Dr. Thorndyke."
 
"Of course I will," said Mrs. Hornby; "instantly; and you need not return it, Dr. Jervis. When you have finished with it, fling it into the fire. I wish never to see it again."
 
But I had been considering the matter, and had come to the conclusion that it would be highly indiscreet to take the book out of Mrs. Hornby's custody, and this I now proceeded to explain.
 
"I have no idea," I said, "for what purpose Dr. Thorndyke wishes to examine the 'Thumbograph,' but it occurs to me that he may desire to put it in evidence, in which case it would be better that it should not go out of your possession for the present. He merely commissioned me to ask for your permission to take a photograph of it."
 
"Oh, if he wants a photograph," said Mrs. Hornby, "I could get one done for him without any difficulty. My nephew Walter would take one for us, I am sure, if I asked him. He is so clever, you know—is he not, Juliet, dear?"
 
"Yes, aunt," replied Miss Gibson quickly, "but I expect Dr. Thorndyke would rather take the photograph himself."
 
"I am sure he would," I agreed. "In fact, a photograph taken by another person would not be of much use to him."
 
"Ah," said Mrs. Hornby in a slightly injured tone, "you think Walter is just an ordinary amateur; but if I were to show you some of the photographs he has taken you would really be surprised. He is remarkably clever, I assure you."
 
"Would you like us to bring the book to Dr. Thorndyke's chambers?" asked Miss Gibson. "That would save time and trouble."
 
"It is excessively good of you—" I began.
 
"Not at all. When shall we bring it? Would you like to have it this evening?"
 
"We should very much," I replied. "My colleague could then examine it and decide what is to be done with it. But it is giving you so much trouble."
 
"It is nothing of the kind," said Miss Gibson. "You would not mind coming with me this evening, would you, aunt?"
 
"Certainly not, my dear," replied Mrs. Hornby, and she was about to enlarge on the subject when Miss Gibson rose and, looking at her watch, declared that she must start on her errand at once. I also rose to make my adieux, and she then remarked—
 
"If you are walking in the same direction as I am, Dr. Jervis, we might arrange the time of our proposed visit as we go along."
 
I was not slow to avail myself of this invitation, and a few seconds later we left the house together, leaving Mrs. Hornby smiling fatuously after us from the open door.
 
"Will eight o'clock suit you, do you think?" Miss Gibson asked, as we walked up the street.
 
"It will do excellently, I should say," I answered. "If anything should render the meeting impossible I will send you a telegram. I could wish that you were coming alone, as ours is to be a business conference."
 
Miss Gibson laughed softly—and a very pleasant and musical laugh it was.
 
"Yes," she agreed. "Dear Mrs. Hornby is a little diffuse and difficult to keep to one subject; but you must be indulgent to her little failings; you would be if you had experienced such kindness and generosity from her as I have."
 
"I am sure I should," I rejoined; "in fact, I am. After all, a little diffuseness of speech and haziness of ideas are no great faults in a generous and amiable woman of her age."
 
Miss Gibson rewarded me for these highly correct sentiments with a little smile of approval, and we walked on for some time in silence. Presently she turned to me with some suddenness and a very earnest expression, and said—
 
"I want to ask you a question, Dr. Jervis, and please forgive me if I beg you to put aside your professional reserve just a little in my favour. I want you to tell me if you think Dr. Thorndyke has any kind of hope or expectation of being able to save poor Reuben from the dreadful peril that threatens him."
 
This was a rather pointed question, and I took some time to consider it before replying.
 
"I should like," I replied at length, "to tell you as much as my duty to my colleague will allow me to; but that is so little that it is hardly worth telling. However, I may say this without breaking any confidence: Dr. Thorndyke has undertaken the case and is working hard at it, and he would, most assuredly, have done neither the one nor the other if he had considered it a hopeless one."
 
"That is a very encouraging view of the matter," said she, "which, had, however, already occurred to me. May I ask if anything came of your visit to Scotland Yard? Oh, please don't think me encroaching; I am so terribly anxious and troubled."
 
"I can tell you very little about the results of our expedition, for I know very little; but I have an idea that Dr. Thorndyke is not dissatisfied with his morning's work. He certainly picked up some facts, though I have no idea of their nature, and as soon as we reached home he developed a sudden desire to examine the 'Thumbograph.'"
 
"Thank you, Dr. Jervis," she said gratefully. "You have cheered me more than I can tell you, and I won't ask you any more questions. Are you sure I am not bringing you out of the way?"
 
"Not at all," I answered hastily. "The fact is, I had hoped to have a little chat with you when we had disposed of the 'Thumbograph,' so I can regard myself as combining a little business with a great deal of pleasure if I am allowed to accompany you."
 
She gave me a little ironical bow as she inquired—
 
"And, in short, I may take it that I am to be pumped?"
 
"Come, now," I retorted. "You have been plying the pump handle pretty vigorously yourself. But that is not my meaning at all. You see, we are absolute strangers to all the parties concerned in this case, which, of course, makes for an impartial estimate of their characters. But, after all, knowledge is more useful to us than impartiality. There is our client, for instance. He impressed us both very favourably, I think; but he might have been a plausible rascal with the blackest of records. Then you come and tell us that he is a gentleman of stainless character and we are at once on firmer ground."
 
"I see," said Miss Gibson thoughtfully; "and suppose that I or some one else had told you things that seemed to reflect on his character. Would they have influenced you in your attitude towards him?"
 
"Only in this," I replied; "that we should have made it our business to inquire into the truth of those reports and ascertain their origin."
 
"That is what one should always do, I suppose," said she, still with an air of deep thoughtfulness which encouraged me to inquire—
 
"May I ask if anyone to your knowledge has ever said anything to Mr. Reuben's disadvantage?"
 
She pondered for some time before replying, and kept her eyes bent pensively on the ground. At length she said, not without some hesitation of manner—
 
"It is a small thing and quite without any bearing on this affair. But it has been a great trouble to me since it has to some extent put a barrier between Reuben and me; and we used to be such close friends. And I have blamed myself for letting it influence me—perhaps unjustly—in my opinion of him. I will tell you about it, though I expect you will think me very foolish.
 
"You must know, then, that Reuben and I used, until about six months ago, to be very much together, though we were only friends, you understand. But we were on the footing of relatives, so there was nothing out of the way in it. Reuben is a keen student of ancient and mediaeval art, in which I also am much interested, so we used to visit the museums and galleries together and get a great deal of pleasure from comparing our views and impressions of what we saw.
 
"About six months ago, Walter took me aside one day and, with a very serious face, asked me if there was any kind of understanding between Reuben and me. I thought it rather impertinent of him, but nevertheless, I told him the truth, that Reuben and I were just friends and nothing more.
 
"'If that is the case,' said he, looking mighty grave, 'I would advise you not to be seen about with him quite so much.'
 
"'And why not?' I asked very naturally.
 
"'Why, the fact is,' said Walter, 'that Reuben is a confounded fool. He has been chattering to the men at the club and seems to have given them the impression that a young lady of means and position has been setting her cap at him very hard, but that he, being a high-souled philosopher above the temptations that beset ordinary mortals, is superior both to her blandishments and her pecuniary attractions. I give you the hint for your own guidance,' he continued, 'and I expect this to go no farther. You mustn't be annoyed with Reuben. The best of young men will often behave like prigs and donkeys, and I have no doubt the fellows have grossly exaggerated what he said; but I thought it right to put you on your guard.'
 
"Now this report, as you may suppose, made me excessively angry, and I wanted to have it out with Reuben then and there. But Walter refused to sanction this—'there was no use in making a scene' he said—and he insisted that the caution was given to me in strict confidence; so what was I to do? I tried to ignore it and treat Reuben as I always had done, but this I found impossible; my womanly pride was much too deeply hurt. And yet I felt it the lowest depth of meanness to harbour such thoughts of him without giving him the opportunity to defend himself. And although it was most unlike Reuben in some respects, it was very like him in others; for he has always expressed the utmost contempt for men who marry for a livelihood. So I have remained on the horns of a dilemma and am there still. What do you think I ought to have done?"
 
I rubbed my chin in some embarrassment at this question. Needless to say, I was most disagreeably impressed by Walter Hornby's conduct, and not a little disposed to blame my fair companion for giving an ear to his secret disparagement of his cousin; but I was obviously not in a position to pronounce, offhand, upon the merits of the case.
 
"The position appears to be this," I said, after a pause, "either Reuben has spoken most unworthily and untruthfully of you, or Walter has lied deliberately about him."
 
"Yes," she agreed, "that is the position; but which of the two alternatives appears to you the more probable?"
 
"That is very difficult to say," I answered. "There is a certain kind of cad who is much given to boastful rhodomontade concerning his conquests. We all know him and can generally spot him at first sight, but I must say that Reuben Hornby did not strike me as that kind of man at all. Then it is clear that the proper course for Walter to have adopted, if he had really heard such rumours, was to have had the matter out with Reuben, instead of coming secretly to you with whispered reports. That is my feeling, Miss Gibson, but, of course, I may be quite wrong. I gather that our two young friends are not inseparable companions?"
 
"Oh, they are very good friends, but you see, their interests and views of life are quite different. Reuben, although an excellent worker in business hours, is a student, or perhaps rather what one would call a scholar, whereas Walter is more a practical man of affairs—decidedly long-headed and shrewd. He is undoubtedly very clever, as Mrs. Hornby said."
 
"He takes photographs, for instance," I suggested.
 
"Yes. But not ordinary amateur photographs; his work is more technical and quite excellent of its kind. For example, he did a most beautiful series of micro-photographs of sections of metalliferous rocks which he reproduced for publication by the collotype process, and even printed off the plates himself."
 
"I see. He must be a very capable fellow."
 
"He is, very," she assented, "and very keen on making a position; but I am afraid he is rather too fond of money for its own sake, which is not a pleasant feature in a young man's character, is it?"
 
I agreed that it was not.
 
"Excessive keenness in money affairs," proceeded Miss Gibson oracularly, "is apt to lead a young man into bad ways—oh, you need not smile, Dr. Jervis, at my wise saws; it is perfectly true, and you know it. The fact is, I sometimes have an uneasy feeling that Walter's desire to be rich inclines him to try what looks like a quick and easy method of making money. He had a friend—a Mr. Horton—who is a dealer on the Stock Exchange and who 'operates' rather largely—'operate' I believe is the expression used, although it seems to be nothing more than common gambling—and I have more than once suspected Walter of being concerned in what Mr. Horton calls 'a little flutter.'"
 
"That doesn't strike me as a very long-headed proceeding," I remarked, with the impartial wisdom of the impecunious, and therefore untempted.
 
"No," she agreed, "it isn't. But your gambler always thinks he is going to win—though you mustn't let me give you the impression that Walter is a gambler. But here is my destination. Thank you for escorting me so far, and I hope you are beginning to feel less like a stranger to the Hornby family. We shall make our appearance to-night at eight punctually."
 
She gave me her hand with a frank smile and tripped up the steps leading to the street door; and when I glanced back, after crossing the road, she gave me a little friendly nod as she turned to enter the house.