“So your net has been sweeping the quiet and pleasant waters of feminine conversation,” remarked Thorndyke when we met at the dinner table and I gave him an outline of my afternoon’s adventures.

“Yes,” I answered, “and here is the catch cleaned and ready for the consumer.”

I laid on the table two of my notebooks in which I had entered such facts as I had been able to extract from my talk with Miss Gibson.

“You made your entries as soon as possible after your return, I suppose?” said Thorndyke ­“while the matter was still fresh?”

“I wrote down my notes as I sat on a seat in Kensington Gardens within five minutes after leaving Miss Gibson.”

“Good!” said Thorndyke.  “And now let us see what you have collected.”

He glanced quickly through the entries in the two books, referring back once or twice, and stood for a few moments silent and abstracted.  Then he laid the little books down on the table with a satisfied nod.

“Our information, then,” he said, “amounts to this:  Reuben is an industrious worker at his business and, in his leisure, a student of ancient and medieval art; possibly a babbling fool and a cad or, on the other hand, a maligned and much-abused man.  “Walter Hornby is obviously a sneak and possibly a liar; a keen man of business, perhaps a flutterer round the financial candle that burns in Throgmorton Street; an expert photographer and a competent worker of the collotype process.  You have done a very excellent day’s work, Jervis.  I wonder if you see the bearing of the facts that you have collected.”

“I think I see the bearing of some of them,” I answered; “at least, I have formed certain opinions.”

“Then keep them to yourself, mon ami, so that I need not feel as if I ought to unbosom myself of my own views.”

“I should be very much surprised if you did, Thorndyke,” I replied, “and should have none the better opinion of you.  I realise fully that your opinions and theories are the property of your client and not to be used for the entertainment of your friends.”

Thorndyke patted me on the back playfully, but he looked uncommonly pleased, and said, with evident sincerity, “I am really grateful to you for saying that, for I have felt a little awkward in being so reticent with you who know so much of this case.  But you are quite right, and I am delighted to find you so discerning and sympathetic.  The least I can do under the circumstances is to uncork a bottle of Pommard, and drink the health of so loyal and helpful a colleague.  Ah!  Praise the gods! here is Polton, like a sacrificial priest accompanied by a sweet savour of roasted flesh.  Rump steak I ween,” he added, sniffing, “food meet for the mighty Shamash (that pun was fortuitous, I need not say) or a ravenous medical jurist.  Can you explain to me, Polton, how it is that your rump steak is better than any other steak?  Is it that you have command of a special brand of ox?”

The little man’s dry countenance wrinkled with pleasure until it was as full of lines as a ground-plan of Clapham Junction.

“Perhaps it is the special treatment it gets, sir,” he replied.  “I usually bruise it in the mortar before cooking, without breaking up the fibre too much, and then I heat up the little cupel furnace to about 600 C, and put the steak in on a tripod.”

Thorndyke laughed outright.  “The cupel furnace, too,” he exclaimed.  “Well, well, ’to what base uses’ ­but I don’t know that it is a base use after all.  Anyhow, Polton, open a bottle of Pommard and put a couple of ten by eight ‘process’ plates in your dark slides.  I am expecting two ladies here this evening with a document.”

“Shall you bring them upstairs, sir?” inquired Polton, with an alarmed expression.

“I expect I shall have to,” answered Thorndyke.

“Then I shall just smarten the laboratory up a bit,” said Polton, who evidently appreciated the difference between the masculine and feminine view as to the proper appearance of working premises.

“And so Miss Gibson wanted to know our private views on the case?” said Thorndyke, when his voracity had become somewhat appeased.

“Yes,” I answered; and then I repeated our conversation as nearly as I could remember it.

“Your answer was very discreet and diplomatic,” Thorndyke remarked, “and it was very necessary that it should be, for it is essential that we show the backs of our cards to Scotland Yard; and if to Scotland Yard, then to the whole world.  We know what their trump card is and can arrange our play accordingly, so long as we do not show our hand.”

“You speak of the police as your antagonists; I noticed that at the ‘Yard’ this morning, and was surprised to find that they accepted the position.  But surely their business is to discover the actual offender, not to fix the crime on some particular person.”

“That would seem to be so,” replied Thorndyke, “but in practice it is otherwise.  When the police have made an arrest they work for a conviction.  If the man is innocent, that is his business, not theirs; it is for him to prove it.  The system is a pernicious one ­especially since the efficiency of a police officer is, in consequence, apt to be estimated by the number of convictions he has secured, and an inducement is thus held out to him to obtain a conviction, if possible; but it is of a piece with legislative procedure in general.  Lawyers are not engaged in academic discussions or in the pursuit of truth, but each is trying, by hook or by crook, to make out a particular case without regard to its actual truth or even to the lawyer’s own belief on the subject.  That is what produces so much friction between lawyers and scientific witnesses; neither can understand the point of view of the other.  But we must not sit over the table chattering like this; it has gone half-past seven, and Polton will be wanting to make this room presentable.”

“I notice you don’t use your office much,” I remarked.

“Hardly at all, excepting as a repository for documents and stationery.  It is very cheerless to talk in an office, and nearly all my business is transacted with solicitors and counsel who are known to me, so there is no need for such formalities.  All right, Polton; we shall be ready for you in five minutes.”

The Temple bell was striking eight as, at Thorndyke’s request, I threw open the iron-bound “oak”; and even as I did so the sound of footsteps came up from the stairs below.  I waited on the landing for our two visitors, and led them into the room.

“I am so glad to make your acquaintance,” said Mrs. Hornby, when I had done the honours of introduction; “I have heard so much about you from Juliet ­”

“Really, my dear aunt,” protested Miss Gibson, as she caught my eye with a look of comical alarm, “you will give Dr. Thorndyke a most erroneous impression.  I merely mentioned that I had intruded on him without notice and had been received with undeserved indulgence and consideration.”

“You didn’t put it quite in that way, my dear,” said Mrs. Hornby, “but I suppose it doesn’t matter.”

“We are highly gratified by Miss Gibson’s favourable report of us, whatever may have been the actual form of expression,” said Thorndyke, with a momentary glance at the younger lady which covered her with smiling confusion, “and we are deeply indebted to you for taking so much trouble to help us.”

“It is no trouble at all, but a great pleasure,” replied Mrs. Hornby; and she proceeded to enlarge on the matter until her remarks threatened, like the rippling circles produced by a falling stone, to spread out into infinity.  In the midst of this discourse Thorndyke placed chairs for the two ladies, and, leaning against the mantelpiece, fixed a stony gaze upon the small handbag that hung from Mrs. Hornby’s wrist.

“Is the ‘Thumbograph’ in your bag?” interrupted Miss Gibson, in response to this mute appeal.

“Of course it is, my dear Juliet,” replied the elder lady.  “You saw me put it in yourself.  What an odd girl you are.  Did you think I should have taken it out and put it somewhere else?  Not that these handbags are really very secure, you know, although I daresay they are safer than pockets, especially now that it is the fashion to have the pocket at the back.  Still, I have often thought how easy it would be for a thief or a pickpocket or some other dreadful creature of that kind, don’t you know, to make a snatch and ­in fact, the thing has actually happened.  Why, I knew a lady ­Mrs. Moggridge, you know, Juliet ­no, it wasn’t Mrs. Moggridge, that was another affair, it was Mrs. ­Mrs. ­dear me, how silly of me! ­now, what was her name?  Can’t you help me, Juliet?  You must surely remember the woman.  She used to visit a good deal at the Hawley-Johnsons’ ­I think it was the Hawley-Johnsons’, or else it was those people, you know ­”

“Hadn’t you better give Dr. Thorndyke the ’Thumbograph’?” interrupted Miss Gibson.

“Why, of course, Juliet, dear.  What else did we come here for?” With a slightly injured expression, Mrs. Hornby opened the little bag and commenced, with the utmost deliberation, to turn out its contents on to the table.  These included a laced handkerchief, a purse, a card-case, a visiting list, a packet of papier poudre, and when she had laid the last-mentioned article on the table, she paused abruptly and gazed into Miss Gibson’s face with the air of one who has made a startling discovery.

“I remember the woman’s name,” she said in an impressive voice.  “It was Gudge ­Mrs. Gudge, the sister-in-law of ­”

Here Miss Gibson made an unceremonious dive into the open bag and fished out a tiny parcel wrapped in notepaper and secured with a silk thread.

“Thank you,” said Thorndyke, taking it from her hand just as Mrs. Hornby was reaching out to intercept it.  He cut the thread and drew from its wrappings a little book bound in red cloth, with the word “Thumbograph” stamped upon the cover, and was beginning to inspect it when Mrs. Hornby rose and stood beside him.

“That,” said she, as she opened the book at the first page, “is the thumb-mark of a Miss Colley.  She is no connection of ours.  You see it is a little smeared ­she said Reuben jogged her elbow, but I don’t think he did; at any rate he assured me he did not, and, you know ­”

“Ah!  Here is one we are looking for,” interrupted Thorndyke, who had been turning the leaves of the book regardless of Mrs. Hornby’s rambling comments; “a very good impression, too, considering the rather rough method of producing it.”

He reached out for the reading lens that hung from its nail above the mantelpiece, and I could tell by the eagerness with which he peered through it at the thumb-print that he was looking for something.  A moment later I felt sure that he had found that something which he had sought, for, though he replaced the lens upon its nail with a quiet and composed air and made no remark, there was a sparkle of the eye and a scarcely perceptible flush of suppressed excitement and triumph which I had begun to recognise beneath the impassive mask that he presented to the world.

“I shall ask you to leave this little book with me, Mrs. Hornby,” he said, breaking in upon that lady’s inconsequent babblings, “and, as I may possibly put it in evidence, it would be a wise precaution for you and Miss Gibson to sign your names ­as small as possible ­on the page which bears Mr. Reuben’s thumb-mark.  That will anticipate any suggestion that the book has been tampered with after leaving your hands.”

“It would be a great impertinence for anyone to make any such suggestion,” Mrs. Hornby began; but on Thorndyke’s placing his fountain pen in her hand, she wrote her signature in the place indicated and handed the pen to Miss Gibson, who signed underneath.

“And now,” said Thorndyke, “we will take an enlarged photograph of this page with the thumb-mark; not that it is necessary that it should be done now, as you are leaving the book in my possession; but the photograph will be wanted, and as my man is expecting us and has the apparatus ready, we may as well despatch the business at once.”

To this both the ladies readily agreed (being, in fact, devoured by curiosity with regard to my colleague’s premises), and we accordingly proceeded to invade the set of rooms on the floor above, over which the ingenious Polton was accustomed to reign in solitary grandeur.

It was my first visit to these mysterious regions, and I looked about me with as much curiosity as did the two ladies.  The first room that we entered was apparently the workshop, for it contained a small woodworker’s bench, a lathe, a bench for metal work and a number of mechanical appliances which I was not then able to examine; but I noticed that the entire place presented to the eye a most unworkmanlike neatness, a circumstance that did not escape Thorndyke’s observation, for his face relaxed into a grim smile as his eye travelled over the bare benches and the clean-swept floor.

From this room we entered the laboratory, a large apartment, one side of which was given up to chemical research, as was shown by the shelves of reagents that covered the wall, and the flasks, retorts and other apparatus that were arranged on the bench, like ornaments on a drawing-room mantelpiece.  On the opposite side of the room was a large, massively-constructed copying camera, the front of which, carrying the lens, was fixed, and an easel or copyholder travelled on parallel guides towards, or away, from it, on a long stand.

This apparatus Thorndyke proceeded to explain to our visitors while Polton was fixing the “Thumbograph” in a holder attached to the easel.

“You see,” he said, in answer to a question from Miss Gibson, “I have a good deal to do with signatures, cheques and disputed documents of various kinds.  Now a skilled eye, aided by a pocket-lens, can make out very minute details on a cheque or bank-note; but it is not possible to lend one’s skilled eye to a judge or juryman, so that it is often very convenient to be able to hand them a photograph in which the magnification is already done, which they can compare with the original.  Small things, when magnified, develop quite unexpected characters; for instance, you have handled a good many postage stamps, I suppose, but have you ever noticed the little white spots in the upper corner of a penny stamp, or even the difference in the foliage on the two sides of the wreath?”

Miss Gibson admitted that she had not.

“Very few people have, I suppose, excepting stamp-collectors,” continued Thorndyke; “but now just glance at this and you will find these unnoticed details forced upon your attention.”  As he spoke, he handed her a photograph, which he had taken from a drawer, showing a penny stamp enlarged to a length of eight inches.

While the ladies were marvelling over this production, Polton proceeded with his work.  The “Thumbograph” having been fixed in position, the light from a powerful incandescent gas lamp, fitted with a parabolic reflector, was concentrated on it, and the camera racked out to its proper distance.

“What are those figures intended to show?” inquired Miss Gibson, indicating the graduation on the side of one of the guides.

“They show the amount of magnification or reduction,” Thorndyke explained.  “When the pointer is opposite 0, the photograph is the same size as the object photographed; when it points to, say, x 4, the photograph will be four times the width and length of the object, while if it should point to, say, / 4, the photograph will be one-fourth the length of the object.  It is now, you see, pointing to x 8, so the photograph will be eight times the diameter of the original thumb-mark.”

By this time Polton had brought the camera to an accurate focus and, when we had all been gratified by a glimpse of the enlarged image on the focussing screen, we withdrew to a smaller room which was devoted to bacteriology and microscopical research, while the exposure was made and the plate developed.  Here, after an interval, we were joined by Polton, who bore with infinite tenderness the dripping negative on which could be seen the grotesque transparency of a colossal thumb-mark.

This Thorndyke scrutinised eagerly, and having pronounced it satisfactory, informed Mrs. Hornby that the object of her visit was attained, and thanked her for the trouble she had taken.

“I am very glad we came,” said Miss Gibson to me, as a little later we walked slowly up Mitre Court in the wake of Mrs. Hornby and Thorndyke; “and I am glad to have seen these wonderful instruments, too.  It has made me realise that something is being done and that Dr. Thorndyke really has some object in view.  It has really encouraged me immensely.”

“And very properly so,” I replied.  “I, too, although I really know nothing of what my colleague is doing, feel very strongly that he would not take all this trouble and give up so much valuable time if he had not some very definite purpose and some substantial reasons for taking a hopeful view.”

“Thank you for saying that,” she rejoined warmly; “and you will let me have a crumb of comfort when you can, won’t you?” She looked in my face so wistfully as she made this appeal that I was quite moved; and, indeed, I am not sure that my state of mind at that moment did not fully justify my colleague’s reticence towards me.

However, I, fortunately, had nothing to tell, and so, when we emerged into Fleet Street to find Mrs. Hornby already ensconced in a hansom, I could only promise, as I grasped the hand that she offered to me, to see her again at the earliest opportunity ­a promise which my inner consciousness assured me would be strictly fulfilled.

“You seem to be on quite confidential terms with our fair friend,” Thorndyke remarked, as we strolled back towards his chambers.  “You are an insinuating dog, Jervis.”

“She is very frank and easy to get on with,” I replied.

“Yes.  A good girl and a clever girl, and comely to look upon withal.  I suppose it would be superfluous for me to suggest that you mind your eye?”

“I shouldn’t, in any case, try to cut out a man who is under a cloud,” I replied sulkily.

“Of course you wouldn’t; hence the need of attention to the ophthalmic member.  Have you ascertained what Miss Gibson’s actual relation is to Reuben Hornby?”

“No,” I answered.

“It might be worth while to find out,” said Thorndyke; and then he relapsed into silence.