V.

The Thinking Machine stared steadily into the eager, exultant eyes of the newspaper man until Hatch at last began to fear that he had been precipitate. After awhile, under close scrutiny, the reporter began to feel convinced that he had made a mistake--he didn't quite see where, but it must be there, and the exultant manner passed. The voice of The Thinking Machine was like a cold shower.

"Remember, Mr. Hatch," he said, critically, "that unless every possible question has been considered one cannot boast of a solution. Is there any possible question lingering yet in your mind?"

The reporter silently considered that for a moment, then:

"Well, I have the main facts, anyway. There may be one or two minor questions left, but the principal ones are answered."

"Then tell me, to the minutest detail, what you have learned, what has happened."

Professor Van Dusen sank back in his old, familiar pose in the large arm chair and Hatch related what he had learned and what he surmised. He related, too, the peculiar circumstances surrounding the wounding of Henley, and right on down to the beginning and end of the interview with Cabell in the latter's apartments. The Thinking Machine was silent for a time, then there came a host of questions.

"Do you know where the woman--Miss Austin--is now?" was the first.

"No," Hatch had to admit.

"Or her precise mental condition?"

"No."

"Or her exact relationship to Cabell?"

"No."

"Do you know, then, what the valet, Jean, knows of the affair?"

"No, not that," said the reporter, and his face flushed under the close questioning. "He was out of the suite every night."

"Therefore might have been the very one who turned on the gas," the other put in testily.

"So far as I can learn, nobody could have gone into that room and turned on the gas," said the reporter, somewhat aggressively. "Henley barred the doors and windows and kept watch, night after night."

"Yet the moment he was exhausted and fell asleep the gas was turned on to kill him," said The Thinking Machine; "thus we see that _he was watched more closely than he watched_."

"I see what you mean now," said Hatch, after a long pause.

"I should like to know what Henley and Cabell and the valet knew of the girl who was found dead," The Thinking Machine suggested. "Further, I should like to know if there was a good-sized mirror--not one set in a bureau or dresser--either in Henley's room or the apartments where the girl was found. Find out this for me and--never mind. I'll go with you."

The scientist left the room. When he returned he wore his coat and hat. Hatch arose mechanically to follow. For a block or more they walked along, neither speaking. The Thinking Machine was the first to break the silence:

"You believe Cabell is the man who attempted to kill Henley?"

"Frankly, yes," replied the newspaper man.

"Why?"

"Because he had the motive--disappointed love."

"How?"

"I don't know," Hatch confessed. "The doors of the Henley suite were closed. I don't see how anybody passed them."

"And the girl? Who killed her? How? Why?"

Disconsolately Hatch shook his head as he walked on. The Thinking Machine interpreted his silence aright.

"Don't jump at conclusions," he advised sharply. "You are confident Cabell was to blame for this--and he might have been, I don't know yet--but you can suggest nothing to show how he did it. I have told you before that imagination is half of logic."

At last the lights of the big apartment house where Henley lived came in sight. Hatch shrugged his shoulders. He had grave doubts--based on what he knew--whether The Thinking Machine would be able to see Cabell. It was nearly eleven o'clock and Cabell was to leave for the South at midnight.

"Is Mr. Cabell here?" asked the scientist of the elevator boy.

"Yes, just about to go, though. He won't see anyone."

"Hand him this note," instructed The Thinking Machine, and he scribbled something on a piece of paper. "He'll see us."

The boy took the paper and the elevator shot up to the fourth floor. After awhile he returned.

"He'll see you," he said.

"Is he unpacking?"

"After he read your note twice he told his valet to unpack," the boy replied.

"Ah, I thought so," said The Thinking Machine.

With Hatch, mystified and puzzled, following, The Thinking Machine entered the elevator to step out a second or so later on the fourth floor. As they left the car they saw the door of Cabell's apartment standing open; Cabell was in the door. Hatch traced a glimmer of anxiety in the eyes of the young man.

"Professor Van Dusen?" Cabell inquired.

"Yes," said the scientist. "It was of the utmost importance that I should see you, otherwise I should not have come at this time of night."

With a wave of his hand Cabell passed that detail. "I was anxious to get away at midnight," he explained, "but, of course, now I shan't go, in view of your note. I have ordered my valet to unpack my things, at least until to-morrow."

The reporter and the scientist passed into the luxuriously furnished apartments. Jean, the valet, was bending over a suit case as they entered, removing some things he had been carefully placing there. He didn't look back or pay the least attention to the visitors.

"This is your valet?" asked The Thinking Machine.

"Yes," said the young man.

"French, isn't he?"

"Yes."

"Speak English at all?"

"Very badly," said Cabell. "I use French when I talk to him."

"Does he know that you are accused of murder?" asked The Thinking Machine, in a quiet, conversational tone.

The effect of the remark on Cabell was startling. He staggered back a step or so as if he had been struck in the face, and a crimson flush overspread his brow. Jean, the valet, straightened up suddenly and looked around. There was a queer expression, too, in his eyes; an expression which Hatch could not fathom.

"Murder?" gasped Cabell, at last.

"Yes, he speaks English all right," remarked The Thinking Machine. "Now, Mr. Cabell, will you please tell me just who Miss Austin is, and where she is, and her mental condition? Believe me, it may save you a great deal of trouble. What I said in the note is not exaggerated."

The young man turned suddenly and began to pace back and forth across the room. After a few minutes he paused before The Thinking Machine, who stood impatiently waiting for an answer.

"I'll tell you, yes," said Cabell, firmly. "Miss Austin is a middle-aged woman whom my sister befriended several times--was, in fact, my sister's governess when she was a child. Of late years she has not been wholly right mentally, and has suffered a great deal of privation. I had about concluded arrangements to put her in a private sanitarium. I permitted her to remain in these rooms in my absence, South. I did not take Jean--he lived in the quarters of the other employees of the place, and gave the apartment entirely to Miss Austin. It was simply an act of charity."

"What was the cause of your sudden determination to go South to-night?" asked the scientist.

"I won't answer that question," was the sullen reply.

There was a long, tense silence. Jean, the valet, came and went several times.

"How long has Miss Austin known Mr. Henley?"

"Presumably since she has been in these apartments," was the reply.

"Are you sure _you_ are not Miss Austin?" demanded the scientist.

The question was almost staggering, not only to Cabell, but to Hatch. Suddenly, with flaming face, the young Southerner leaped forward as if to strike down The Thinking Machine.

"That won't do any good," said the scientist, coldly. "Are you sure you are not Miss Austin?" he repeated.

"Certainly I am not Miss Austin," responded Cabell, fiercely.

"Have you a mirror in these apartments about twelve inches by twelve inches?" asked The Thinking Machine, irrelevantly.

"I--I don't know," stammered the young man. "I--have we, Jean?"

"_Oui_," replied the valet.

"Yes," snapped The Thinking Machine. "Talk English, please. May I see it?"

The valet, without a word but with a sullen glance at the questioner, turned and left the room. He returned after a moment with the mirror. The Thinking Machine carefully examined the frame, top and bottom and on both sides. At last he looked up; again the valet was bending over a suit case.

"Do you use gas in these apartments?" the scientist asked suddenly.

"No," was the bewildered response. "What is all this, anyway?"

Without answering, The Thinking Machine drew a chair up under the chandelier where the gas and electric fixtures were and began to finger the gas tips. After awhile he climbed down and passed into the next room, with Hatch and Cabell, both hopelessly mystified, following. There the scientist went through the same process of fingering the gas jets. Finally, one of the gas tips came out in his hand.

"Ah," he exclaimed, suddenly, and Hatch knew the note of triumph in it. The jet from which the tip came was just on a level with his shoulder, set between a dressing table and a window. He leaned over and squinted at the gas pipe closely. Then he returned to the room where the valet was.

"Now, Jean," he began, in an even, calm voice, "please tell me _if you did or did not kill Miss Regnier purposely?_"

"I don't know what you mean," said the servant sullenly, angrily, as he turned on the scientist.

"You speak very good English now," was The Thinking Machine's terse comment. "Mr. Hatch, lock the door and use this 'phone to call the police."

Hatch turned to do as he was bid and saw a flash of steel in young Cabell's hand, which was drawn suddenly from a hip pocket. It was a revolver. The weapon glittered in the light, and Hatch flung himself forward. There was a sharp report, and a bullet was buried in the floor.