Mrs. Dudley left the room an instant and returned with a cabinet photograph. Hatch and the scientist looked at it together; it was unmistakably the man in the motor boat.
"You can do nothing yourself," said The Thinking Machine at last, and he moved as if to go. "Within a few hours we will have the guilty person. You may rest assured that your name will be in no way brought into the matter unpleasantly."
Hatch glanced at his companion; he thought he detected a sinister note in the soothing voice, but the face expressed nothing. Mrs. Dudley ushered them into the hall; Osaka stood at the front door. They passed out and the door closed behind them.
Hatch started down the steps but The Thinking Machine stopped at the door and tramped up and down. The reporter turned back in astonishment. In the dim reflected light he saw the scientist's finger raised, enjoining silence, then saw him lean forward suddenly with his ear pressed to the door. After a little he rapped gently. The door was opened by Osaka who obeyed a beckoning motion of the scientist's hand and came out. Silently he was led off the veranda into the yard; he appeared in no way surprised.
"Your master, Mr. Dudley, has been murdered," declared The Thinking Machine quietly, to Osaka. "We know that Mrs. Dudley killed him," he went on as Hatch stared, "but I have told her she is not suspected. We are not officers and cannot arrest her. Can you go with us to Boston, without the knowledge of anyone here and tell what you know of the quarrel between husband and wife to the police?"
Osaka looked placidly into the eager face.
"I had the honour to believe that the circumstances would not be recognized," he said finally. "Since you know, I will go."
"We will drive down a little way and wait for you."
The Japanese disappeared into the house again. Hatch was too astounded to speak, but followed The Thinking Machine into the carry-all. It drove away a hundred yards and stopped. After a few minutes an impalpable shadow came toward them through the night. The scientist peered out as it came up.
"Osaka?" he asked softly.
"Yes."
An hour later the three men were on a train, Boston bound. Once comfortably settled the scientist turned to the Japanese.
"Now if you will please tell me just what happened the night of the ball?" he asked, "and the incidents leading up to the disagreement between Mr. and Mrs. Dudley?"
"He drank elaborately," Osaka explained reluctantly, in his quaint English, "and when drinking he was brutal to the honourable lady. Twice with my own eyes I saw him strike her-once in Japan where I entered his service while they were on a wedding journey, and once here. On the night of the ball he was immeasurably intoxicated, and when he danced he fell down to the floor. The honourable lady was chagrined and angry-she had been angry before. There was some quarrel which I am not comprehensive of. They had been widely divergent for several months. It was, of course, not prominent in the presence of others."
"And the cut on his arm where the court plaster was applied?" asked the scientist. "Just how did he get that?"
"It was when he fell down," continued the Japanese. "He reached to embrace a carved chair and the carved wood cut his arm. I assisted him to his feet and the honourable lady sent me to her room to get court plaster. I acquired it from her dressing table and she placed it on the cut."
"That makes the evidence against her absolutely conclusive," remarked The Thinking Machine, as if finally. There was a little pause, and then: "Do you happen to know just how Mrs. Dudley placed the body in the boat?"
"I have not that honour," said Osaka. "Indeed I am not comprehensive of anything that happened after the court plaster was put on except that Mr. Dudley was affected some way and went out of the house. Mrs. Dudley, too, was not in the ball room for ten minutes or so afterwards."
Hutchinson Hatch stared frankly into the face of The Thinking Machine; there was nothing to he read there. Still deeply thoughtful Hatch heard the brakeman bawl "Boston" and mechanically followed the scientist and Osaka out of the station into a cab. They were driven immediately to Police Headquarters. Detective Mallory was just about to go home when they entered his office.
"It may enlighten you, Mr. Mallory," announced the scientist coldly, "to know that the man in the motor boat was not a French naval officer who died of natural causes-he was Langham Dudley, a millionaire ship owner. He was murdered. It just happens that I know the person who did it."
The detective arose in astonishment and stared at the slight figure before him inquiringly; he knew the man too well to dispute any assertion he might make.
"Who is the murderer?" he asked.
The Thinking Machine closed the door and the spring lock clicked.
"That man there," he remarked calmly, turning on Osaka.
For one brief instant there was a pause and silence; then the detective advanced upon the Japanese with hand outstretched. The agile Osaka leapt suddenly, as a snake strikes; there was a quick, fierce struggle and Detective Mallory sprawled on the floor. There had been just a twist of the wrist-a trick of jiu jitsu-and Osaka had flung himself at the locked door. As he fumbled there Hatch, deliberately and without compunction, raised a chair and brought it down on his head. Osaka sank down without a sound.
It was an hour before they brought him around again. Meanwhile the detective had patted and petted half a dozen suddenly acquired bruises, and had then searched Osaka. He found nothing to interest him save a small bottle. He uncorked it and started to smell it when The Thinking Machine snatched it away.
"You fool, that'll kill you!" he exclaimed.
Osaka sat, lashed hand and foot to a chair, in Detective Mallory's office-so placed by the detective for safe keeping. His face was no longer expressionless; there were fear and treachery and cunning there. So he listened, perforce, to the statement of the case by The Thinking Machine who leaned back in his chair, squinting steadily upward and with his long, slender fingers pressed together.
"Two and two make four, not some times but all the time," he began at last as if disputing some previous assertion. "As the figure two, wholly disconnected from any other, gives small indication of a result, so is an isolated fact of little consequence. Yet that fact added to another, and the resulting fact added to a third, and so on, will give a final result. That result, if every fact is considered, must be correct. Thus any problem may be solved by logic; logic is inevitable.
"In this case the facts, considered singly, might have been compatible with either a natural death, suicide, or murder-considered together they proved murder. The climax of this proof was the removal of the maker's name from the dead man's shoes, and a fact strongly contributory was the attempt to destroy the identity of the boat. A subtle mind lay back of it all."
"I so regarded it," said Detective Mallory. "I was confident of murder until the Medical Examiner--"
"We prove a murder," The Thinking Machine went on serenely. "The method? I was with Dr. Clough at the autopsy. There was no shot, or knife wound, no poison in the stomach. Knowing there was murder I sought further. Then I found the method in a slight, jagged wound on the left arm. It had been covered with court plaster. The heart showed constriction without apparent cause, and while Dr. Clough examined it I took off this court plaster. Its odour, an unusual one, told me that poison had been transfused into the blood through the wound. So two and two had made four.
"Then-what poison? A knowledge of botany aided me. I recognized faintly the trace of an odour of an herb which is not only indigenous to, but grows exclusively in Japan. Thus a Japanese poison. Analysis later in my laboratory proved it was a Japanese poison, virulent, and necessarily slow to act unless it is placed directly in an artery. The poison on the court plaster and that you took from Osaka are identical."
The scientist uncorked the bottle and permitted a single drop of a green liquid to fall on his handkerchief. He allowed a minute or more for evaporation then handed it to Detective Mallory who sniffed at it from a respectful distance. Then The Thinking Machine produced the bit of court plaster he had taken from the dead man's arm, and again the detective sniffed.
"The same," the scientist resumed as he touched a lighted match to the handkerchief and watched it crumble to ashes, "and so powerful that in its pure state mere inhalation is fatal. I permitted Dr. Clough to make public his opinion-heart failure-after the autopsy for obvious reasons. It would reassure the murderer for instance if he saw it printed, and besides Dudley did die from heart failure; the poison caused it.
"Next came identification. Mr. Hatch learned that no French war ship had been within hundreds of miles of Boston for months. The one seen by Captain Barber might have been one of our own. This man was supposed to be a French naval officer, and had been dead less than eight hours. Obviously he did not come from a ship of his own country. Then from where?
"I know nothing of uniforms, yet I examined the insignia on the arms and shoulders closely after which I consulted my encyclopaedia. I learned that while the uniform was more French than anything else it was really the uniform of no country, because it was not correct. The insignia were mixed.
"Then what? There were several possibilities, among them a fancy dress ball was probable. Absolute accuracy would not be essential there. Where had there been a fancy dress ball? I trusted to the newspapers to tell me that. They did. A short dispatch from a place on the North Shore stated that on the night before the man was found dead there had been a fancy dress ball at the Langham Dudley estate.
"Now it is as necessary to remember every fact in solving a problem as it is to consider every figure in arithmetic. Dudley! Here was the "D" tattooed on the dead man's hand. 'Who's Who' showed that Langham Dudley married Edith Marston Belding. Here was the 'E. M. B.' on the handkerchief in the boat. Langham Dudley was a ship owner, had been a sailor, was a millionaire. Possibly this was his own boat built in France."
Detective Mallory was staring into the eyes of The Thinking Machine in frank admiration; Osaka to whom the narrative had thus far been impersonal, gazed, gazed as if fascinated. Hutchinson Hatch, reporter, was drinking in every word greedily.
"We went to the Dudley place," the scientist resumed after a moment. "This Japanese opened the door. Japanese poison! Two and two were still making four. But I was first interested in Mrs. Dudley. She showed no agitation and told me frankly that she placed the court plaster on her husband's arm, and that it came from her room. There was instantly a doubt as to her connection with the murder; her immediate frankness aroused it.
"Finally, with my hand on her pulse-which was normal-I told her as brutally as I could that her husband had been murdered. Her pulse jumped frightfully and as I told her the cause of death it wavered, weakened and she fainted. Now if she had known her husband were dead-even if she had killed him-a mere statement of his death would not have caused that pulse. Further I doubt if she could have disposed of her husband's body in the motor boat. He was a large man and the manner of her dress even, was against this. Therefore she was innocent.
"And then? The Japanese, Osaka, here. I could see the door of the boat house from the room where we were. Mrs. Dudley asked Osaka if Mr. Dudley's boat wase in the house. He said he didn't know. Then she sent him to see. He returned and said the boat was not there, yet he had not gone to the boat house at all. Ergo, he knew the boat was not there. He may have learned it from another servant, still it was a point against him."
Again the scientist paused and squinted at the Japanese. For a moment Osaka withstood the gaze, then his beady eyes shifted and he moved uncomfortably.
"I tricked Osaka into coming here by a ludicrously simple expedient," The Thinking Machine went on steadily. "On the train I asked if he knew just how Mrs. Dudley got the body of her husband into the boat. Remember at this point he was not supposed to know that the body had been in a boat at all. He said he didn't know and by that very answer admitted that he knew the body had been placed in the boat. He knew because he put it there himself. He didn't merely throw it in the water because he had sense enough to know if the tide didn't take it out it would rise, and possibly be found.
"After the slight injury Mr. Dudley evidently wandered out toward the boat house. The poison was working, and perhaps he fell. Then this man removed all identifying marks, even to the name in the shoes, put the body in the boat and turned on full power. He had a right to assume that the boat would be lost, or that the dead man would be thrown out. Wind and tide and a loose rudder brought it into Boston Harbour. I do not attempt to account for the presence of Mrs. Dudley's handkerchief in the boat. It might have gotten there in one of a hundred ways."
"How did you know husband and wife had quarrelled?" asked Hatch.
"Surmise to account for her not knowing where he was," replied The Thinking Machine. "If they had had a violent disagreement it was possible that he would have gone away without telling her, and she would not have been particularly worried, at least up to the time we saw her. As it was she presumed he was in Boston; perhaps Osaka here gave her that impression?"
The Thinking Machine turned and stared at the Japanese curiously.
"Is that correct?" he asked.
Osaka did not answer.