She seated herself in the chair that Thornd.y.k.e placed for her, and continued in a brisk and business-like manner-

"I must tell you who I am in order to explain my visit to you. For the last six years I have lived with Mr. and Mrs. Hornby, although I am no relation to them. I first came to the house as a sort of companion to Mrs. Hornby, though, as I was only fifteen at the time, I need hardly say that my duties were not very onerous; in fact, I think Mrs. Hornby took me because I was an orphan without the proper means of getting a livelihood, and she had no children of her own.

"Three years ago I came into a little fortune which rendered me independent; but I had been so happy with my kind friends that I asked to be allowed to remain with them, and there I have been ever since in the position of an adopted daughter. Naturally, I have seen a great deal of their nephews, who spend a good part of their time at the house, and I need not tell you that the horrible charge against Reuben has fallen upon us like a thunderbolt. Now, what I have come to say to you is this: I do not believe that Reuben stole those diamonds. It is entirely out of character with all my previous experience of him. I am convinced that he is innocent, and I am prepared to back my opinion."

"In what way?" asked Thornd.y.k.e.

"By supplying the sinews of war," replied Miss Gibson. "I understand that legal advice and a.s.sistance involves considerable expense."

"I am afraid you are quite correctly informed," said Thornd.y.k.e.

"Well, Reuben's pecuniary resources are, I am sure, quite small, so it is necessary for his friends to support him, and I want you to promise me that nothing shall be left undone that might help to prove his innocence if I make myself responsible for any costs that he is unable to meet. I should prefer, of course, not to appear in the matter, if it could be avoided."

"Your friendship is of an eminently practical kind, Miss Gibson," said my colleague, with a smile. "As a matter of fact, the costs are no affair of mine. If the occasion arose for the exercise of your generosity you would have to approach Mr. Reuben's solicitor through the medium of your guardian, Mr. Hornby, and with the consent of the accused. But I do not suppose the occasion will arise, although I am very glad you called, as you may be able to give us valuable a.s.sistance in other ways. For example, you might answer one or two apparently impertinent questions."

"I should not consider any question impertinent that you considered necessary to ask," our visitor replied.

"Then," said Thornd.y.k.e, "I will venture to inquire if any special relations exist between you and Mr. Reuben."

"You look for the inevitable motive in a woman," said Miss Gibson, laughing and flushing a little. "No, there have been no tender pa.s.sages between Reuben and me. We are merely old and intimate friends; in fact, there is what I may call a tendency in another direction-Walter Hornby."

"Do you mean that you are engaged to Mr. Walter?"

"Oh, no," she replied; "but he has asked me to marry him-he has asked me, in fact, more than once; and I really believe that he has a sincere attachment to me."

She made this latter statement with an odd air, as though the thing a.s.serted were curious and rather incredible, and the tone was evidently noticed by Thornd.y.k.e as well as me for he rejoined-

"Of course he has. Why not?"

"Well, you see," replied Miss Gibson, "I have some six hundred a year of my own and should not be considered a bad match for a young man like Walter, who has neither property nor expectations, and one naturally takes that into account. But still, as I have said, I believe he is quite sincere in his professions and not merely attracted by my money."

"I do not find your opinion at all incredible," said Thornd.y.k.e, with a smile, "even if Mr. Walter were quite a mercenary young man-which, I take it, he is not."

Miss Gibson flushed very prettily as she replied-

"Oh, pray do not trouble to pay me compliments; I a.s.sure you I am by no means insensible of my merits. But with regard to Walter Hornby, I should be sorry to apply the term 'mercenary' to him, and yet-well, I have never met a young man who showed a stronger appreciation of the value of money. He means to succeed in life and I have no doubt he will."

"And do I understand that you refused him?"

"Yes. My feelings towards him are quite friendly, but not of such a nature as to allow me to contemplate marrying him."

"And now, to return for a moment to Mr. Reuben. You have known him for some years?"

"I have known him intimately for six years," replied Miss Gibson.

"And what sort of character do you give him?"

"Speaking from my own observation of him," she replied, "I can say that I have never known him to tell an untruth or do a dishonourable deed. As to theft, it is merely ridiculous. His habits have always been inexpensive and frugal, he is unambitious to a fault, and in respect to the 'main chance' his indifference is as conspicuous as Walter's keenness. He is a generous man, too, although careful and industrious."

"Thank you, Miss Gibson," said Thornd.y.k.e. "We shall apply to you for further information as the case progresses. I am sure that you will help us if you can, and that you can help us if you will, with your clear head and your admirable frankness. If you will leave us your card, Dr. Jervis and I will keep you informed of our prospects and ask for your a.s.sistance whenever we need it."

After our fair visitor had departed, Thornd.y.k.e stood for a minute or more gazing dreamily into the fire. Then, with a quick glance at his watch, he resumed his hat and, catching up the microscope, handed the camera case to me and made for the door.

"How the time goes!" he exclaimed, as we descended the stairs; "but it hasn't been wasted, Jervis, hey?"

"No, I suppose not," I answered tentatively.

"You suppose not!" he replied. "Why here is as pretty a little problem as you could desire-what would be called in the jargon of the novels, a psychological problem-and it is your business to work it out, too."

"You mean as to Miss Gibson's relations with these two young men?"

Thornd.y.k.e nodded.

"Is it any concern of ours?" I asked.

"Certainly it is," he replied. "Everything is a concern of ours at this preliminary stage. We are groping about for a clue and must let nothing pa.s.s unscrutinised."

"Well, then, to begin with, she is not wildly infatuated with Walter Hornby, I should say."

"No," agreed Thornd.y.k.e, laughing softly; "we may take it that the canny Walter has not inspired a grand pa.s.sion."

"Then," I resumed, "if I were a suitor for Miss Gibson's hand, I think I would sooner stand in Reuben's shoes than in Walter's."

"There again I am with you," said Thornd.y.k.e. "Go on."

"Well," I continued, "our fair visitor conveyed to me the impression that her evident admiration of Reuben's character was tempered by something that she had heard from a third party. That expression of hers, 'speaking from my own observation,' seemed to imply that her observations of him were not in entire agreement with somebody else's."

"Good man!" exclaimed Thornd.y.k.e, slapping me on the back, to the undissembled surprise of a policeman whom we were pa.s.sing; "that is what I had hoped for in you-the capacity to perceive the essential underneath the obvious. Yes; somebody has been saying something about our client, and the thing that we have to find out is, what is it that has been said and who has been saying it. We shall have to make a pretext for another interview with Miss Gibson."

"By the way, why didn't you ask her what she meant?" I asked foolishly.

Thornd.y.k.e grinned in my face. "Why didn't you?" he retorted.

"No," I rejoined, "I suppose it is not politic to appear too discerning. Let me carry the microscope for a time; it is making your arm ache, I see."

"Thanks," said he, handing the case to me and rubbing his fingers; "it is rather ponderous."

"I can't make out what you want with this great instrument," I said. "A common pocket lens would do all that you require. Besides, a six-inch objective will not magnify more than two or three diameters."

"Two, with the draw-tube closed," replied Thornd.y.k.e, "and the low-power eye-piece brings it up to four. Polton made them both for me for examining cheques, bank-notes and other large objects. But you will understand when you see me use the instrument, and remember, you are to make no comments."

We had by this time arrived at the entrance to Scotland Yard, and were pa.s.sing up the narrow thoroughfare, when we encountered a uniformed official who halted and saluted my colleague.

"Ah, I thought we should see you here before long, doctor," said he genially. "I heard this morning that you have this thumb-print case in hand."

"Yes," replied Thornd.y.k.e; "I am going to see what can be done for the defence."

"Well," said the officer as he ushered us into the building, "you've given us a good many surprises, but you'll give us a bigger one if you can make anything of this. It's a foregone conclusion, I should say."