"There are two plates left," he remarked, as he drew out the second dark slide. "I think I will take a record of the blood-stain on them."
He accordingly made two more exposures—one of the larger blood-stain and one of the smaller smears.
"There," said he, with an air of satisfaction, as he proceeded to pack up what the inspector described as his "box of tricks." "I think we have all the data that we can squeeze out of Scotland Yard, and I am very much obliged to you, Mr. Singleton, for giving so many facilities to your natural enemy, the counsel for the defence."
"Not our natural enemies, doctor," protested Mr. Singleton. "We work for a conviction, of course, but we don't throw obstacles in the way of the defence. You know that perfectly well."
"Of course I do, my dear sir," replied Thorndyke, shaking the official by the hand. "Haven't I benefited by your help a score of times? But I am greatly obliged all the same. Good-bye."
"Good-bye, doctor. I wish you luck, though I fear you will find it 'no go' this time."
"We shall see," replied Thorndyke, and with a friendly wave of the hand to the inspector he caught up the two cases and led the way out of the building.
CHAPTER IV
CONFIDENCES
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