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, × 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 × 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.
Committed for Trial
Thorndyke's hint as to the possible danger foreshadowed by my growing intimacy with Juliet Gibson had come upon me as a complete surprise, and had, indeed, been resented by me as somewhat of an impertinence. Nevertheless, it gave me considerable food for meditation, and I presently began to suspect that the watchful eyes of my observant friend might have detected something in my manner towards Miss Gibson suggestive of sentiments that had been unsuspected by myself.
Of course it would be absurd to suppose that any real feeling could have been engendered by so ridiculously brief an acquaintance. I had only met the girl three times, and even now, excepting for business relations, was hardly entitled to more than a bow of recognition. But yet, when I considered the matter impartially and examined my own consciousness, I could not but recognise that she had aroused in me an interest which bore no relation to the part that she had played in the drama that was so slowly unfolding. She was undeniably a very handsome girl, and her beauty was of a type that specially appealed to me—full of dignity and character that gave promise of a splendid middle age. And her personality was in other ways not less attractive, for she was frank and open, sprightly and intelligent, and though evidently quite self-reliant, was in nowise lacking in that