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 poudré, 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
