For a moment the eyes of the two men met; the same thought had come to them both. The Thinking Machine voiced it.
"Another one!" he said. "The third!"
With no other word he turned and went out; Martha followed him grumblingly. Hatch shuddered a little. The hand of the clock went on to half past seven, to eight. At twenty minutes past eight the scientist reentered the laboratory.
"That fifteen minutes Martha was unconscious probably cost a man's life, and certainly lost to us an immediate solution of the riddle," he declared peevishly. "If she had told us before she fainted there is a chance that the operator would have remembered the number. As it is, there have been fifty calls since, and there's no record." He spread his slender hands helplessly. "The manager is trying to find the calling number. Anyway, we'll know to-morrow. Meanwhile, try to see Mr. Willing to-night, and find out about what relationship, if any, exists between Miss Danbury and Sumner; also, see Professor Meredith."
The newspaper man telephoned to Mr. Willing's home in Melrose to see if he was in; he was not. On a chance he telephoned to his office. He hardly expected an answer, and he got none. So it was not until four o'clock in the morning that the third tragedy in the series came to light.
The scrubwomen employed in the great building where Mr. Willing had his law offices entered the suite to clean up. They found Mr. Willing there, gagged, bound hand and foot, and securely lashed to a chair. He was alive, but apparently unconscious from exhaustion. Directly facing him his secretary, Maxwell Pittman, sat dead in his chair. On his face, dark in death, as are the faces of those who die of strangulation, was an expression of unspeakable terror. His parted lips were slightly bruised, as if from a light blow; in his left cheek was an insignificant, bloodless wound!
Within an hour Detective Mallory was on the scene. By that time Mr. Willing, under the influence of stimulants, was able to talk.
"I have no idea what happened," he explained. "It was after six o'clock, and my secretary and I were alone in the offices, finishing up some work. He had stepped into another room for a moment, and I was at my desk. Some one crept up behind me, and held a drugged cloth to my nostrils. I tried to shout, and struggled, but everything grew black, and that's all I know. When I came to myself poor Pittman was there, just as you see him."
Snooping about the offices, Mallory came upon a small lace handkerchief. He seized upon it tensely, and as he raised it to examine it he became conscious of a strong odor of drugs. In one corner of the handkerchief there was a monogram.
" 'C. M.,' " he read; his eyes blazed. "Cecelia Montgomery!"
In the grip of an uncontrollable excitement Hutchinson Hatch bulged in upon The Thinking Machine in his laboratory.
"There was another," he announced.
"I know it," said The Thinking Machine, still bent over his worktable. "Who was it?"
"Maxwell Pittman," and Hatch related the story.
"There may be two more," the scientist remarked. "Be good enough to call a cab."
"Two more?" Hatch gasped in horror. "Already dead?"
"There may be, I said. One, Cecelia Montgomery, the other the unknown who called on the telephone last night." He started away, then returned to his worktable. "Here's rather an interesting experiment," he said. "See this tube," and he held aloft a heavy glass vessel, closed at one end, and with a stopcock at the other. "Observe. I'll place this heavy piece of rubber over the mouth of the tube, and then turn the stopcock." He suited the action to the word. "Now take it off."
The reporter tugged at it until the blood rushed to his face, but was unable to move it. He glanced up at the scientist in perplexity.
"What hold it there?"
"Vacuum," was the reply. "You may tear it to pieces, but no human power can pull it away whole." He picked up a steel bodkin, and thrust it through the rubber into the mouth of the tube. As he withdrew it, came a sharp, prolonged, hissing sound. Half a minute later the rubber fell off. "The vacuum is practically perfect-something like one-millionth of an atmosphere. The pin hole permits the air to fill the tube, the tremendous pressure against the rubber is removed, and--" He waved his slender hands.
In that instant a germ of comprehension was born in Hatch's brain; he was remembering some college experiments.
"If I should place that tube to your lips," The Thinking Machine resumed, "and turn the stopcock, you would never speak again, never scream, never struggle. It would jerk every particle of air out of your body, paralyze you; within two minutes you would be dead. To remove the tube I should thrust the bodkin through your cheek, say your left, and withdraw it--"
Hatch gasped as the full horror of the thing burst upon him. "Absence of air in the lungs," the examining physicians had said.
"You see, there was no mystery in the manner of the deaths of these three," The Thinking Machine pointed out. "You knew what I have shown you, the physicians knew it, but neither of you knew you knew it. Genius is the ability to apply the knowledge you may have, not the ability to acquire it." His manner changed abruptly. "Please call a cab," he said again.
Together they were driven straight to the university, and shown into Professor Meredith's study. Professor Meredith showed his astonishment plainly at the visit, and astonishment became indignant amazement at the first question.
"Mr. Meredith, can you account for every moment of your time from mid-afternoon yesterday until four o'clock this morning?" The Thinking Machine queried flatly. "Don't misunderstand me-I mean every moment covering the time in which it is possible that Maxwell Pittman was murdered?"
"Why, it's a most outrageous--" Professor Meredith exploded.
"I'm trying to save you from arrest," the scientist explained curtly. "If you can account for all that time, and prove your statement, believe me, you had better prepare to do so. Now, if you could give me any information as to--"
"Who the devil are you?" demanded Professor Meredith belligerently. "What do you mean by daring to suggest--"
"My name is Van Dusen," said The Thinking Machine, "Augustus S. F. X. Van Dusen. Long before your time I held the chair of philosophy in this university. I vacated it by request. Later the university honored me with a degree of LL. D."
The result of the self-introduction was astonishing. Professor Meredith, in the presence of the master mind in the sciences, was a different man.
"I beg you pardon," he began.
"I'm curious to know if you are at all acquainted with Miss Danbury's family history," the scientist went on. "Meanwhile, Mr. Hatch, take the cab, and go straight and measure the precise width of the bruise on Pittman's lips; also, see Mr. Willing, if he is able to receive you, and ask him what he can give you as to Miss Danbury's history-I mean her family, her property, her connections, all about everything. Meet me at my house in a couple of hours."
Hatch went out, leaving them together. When he reached the scientist's home The Thinking Machine was just coming out.
"I'm on my way to see Mr. George Parsons, the so-called copper king," he volunteered. "Come along."
From that moment came several developments so curious, and bizarre, and so widely disassociated that Hatch could make nothing of them at all. Nothing seemed to fit into anything else. For instance, The Thinking Machine's visit to Mr. Parsons' office.
"Please ask Mr. Parsons if he will see Mr. Van Dusen?" he requested of an attendant.
"What about?" the query came from Mr. Parsons.
"It is a matter of life and death," the answer went back.
"Whose?" Mr. Parsons wanted to know.
"His!" The scientist's answer was equally short.
Immediately afterward The Thinking Machine disappeared inside. Ten minutes later he came out, and he and Hatch went off together, stopping at a toy shop to buy a small, high-grade, hard-rubber ball; and later at a department store to purchase a vicious-looking hatpin.
"You failed to inform me, Mr. Hatch, of the measurement of the bruise?"
"Precisely one and a quarter inches."
"Thanks! And what did Mr. Willing say?"
"I didn't see him as yet. I have an appointment to see him in an hour from now."
"Very well," and The Thinking Machine nodded his satisfaction. "When you see him, will you be good enough to tell him, please, that I know-I know, do you understand?-who killed Miss Danbury, and Sumner, and Pittman. You can't make it too strong. I know-do you understand?"
"Do you know?" Hatch demanded quickly.
"No," frankly. "But convince him that I do, and add that to-morrow at noon I shall place the extraordinary facts I have gathered in possession of the police. At noon, understand; and I know!" He was thoughtful a moment. "You might add that I have informed you that the guilty person is a person of high position, whose name has been in no way connected with the crimes-that is, unpleasantly. You don't know that name; no one knows it except myself. I shall give it to the police at noon to-morrow."
"Anything else?"