The gray hand of Death had already left its ashen mark upon the wrinkled, venomous face of the old man, who lay huddled up in bed. Save for the feverishly brilliant eyes — cunning, vindictive, hateful — there seemed to be no spark of life in the aged form. The withered lips were mute, and the thin, yellow, claw-like hands lay helplessly outstretched on the white sheets. All physical power was gone; only the brain remained doggedly alive. Two men and two women stood beside the death bed. Upon each in turn the glittering eyes rested with the merciless, unreasoning hatred of age. Crouched on the floor was a huge St. Bernard dog; and on a perch across the room was a parrot which screeched abominably.

The gloom of the wretched little room was suddenly relieved by a ruddy sunbeam which shot athwart the bed and lighted the scene fantastically. The old man noted it, and his lips curled into a hideous smile.

“That’s the last sun I’ll ever see,” he piped feebly. “I’m dying — dying! Do you hear? And you’re all glad of it, every one of you. Yes, you are! You are glad of it because you want my money. You came here to make me believe you were paying a last tribute of respect to your old grandfather. But that isn’t it. It’s the money you want — the money! But I’ve got a surprise for you. You’ll never get the money. It’s hidden safely — you’ll never get it. You all hate me, you have hated me for years, and after that sun dies you’ll all hate me worse. But not more than I hate you. You’ll all hate me worse then, because I’ll be gone and you’ll never know where the money is hidden. It will lie there safely where I put it, rotting and crumbling away; but you shall never warm your fingers with it! It’s hidden — hidden — hidden!”

There was rasping in the shrunken throat, a deeply drawn breath, then the figure stiffened and a distorted soul passed out upon the Eternal Way.

Martha held a card within the blinding light of the reflector, and Professor Augustus S. F. X. Van Dusen, with his hands immersed to the elbows in some chemical mess, squinted at it.

“Dr. Walter Ballard,” he read. “Show him in.”

After a moment Dr. Ballard entered. The scientist was still absorbed in his labors, but paused long enough to jerk his head toward a chair. Dr. Ballard accepted this as an invitation and sat down, staring curiously at the singular, childlike figure of this eminent man of science, at the mop of tangled, straw yellow hair, the enormous brow, and the peering blue eyes.

“Well?” demanded the scientist abruptly.

“I beg your pardon,” began Dr. Ballard with a little start. “Your name was mentioned to me sometime ago by a newspaper reporter, Hutchinson Hatch, whom I chanced to meet in his professional capacity. He suggested then that I come and see you, but I thought it useless. Now the affair in which we were both interested at that time seems hopelessly beyond solution, so I come to you for aid.

“We want to find one million dollars in gold and United States bonds, which were hidden by my grandfather, John Walter Ballard, sometime before his death just a month ago. The circumstances are altogether out of the ordinary.”

The Thinking Machine abandoned his labors, and dried his hands carefully, after which he took a seat facing Dr. Ballard. “Tell me about it,” he commanded.

“Well,” began Dr. Ballard reminiscently, as he settled back in his chair, “the old man — my grandfather — died, as I said, a month ago. He was nearly eighty-six, and the last five or six years of his life he spent as a recluse in a little hut twenty miles from the city, a place some distance from any other house. He had a spot of ground there, half an acre or so, and lived like a pauper, despite the fact that he was worth at least a million dollars. Previous to the time he went there to live, there had been an estrangement with my family, his sole heirs. My family consists of myself, wife, son, and daughter.

“My grandfather lived in the house with me for ten years before he went out to this hut; and why he left us then is not clear to any member of my family, unless,” and he shrugged his shoulders, “he was mentally unbalanced. Anyway, he went. He would neither come to see us, nor would he permit us to go to see him. As far as we know, he owned no real property of any sort, except this miserable little place, worth altogether — furnishing and all — not more than a thousand or twelve hundred dollars.

“Well, about a month ago some one stopped at the hut for something and found he was ill. I was notified, and with my wife, son and daughter went to see what we could do. He took occasion on his death bed to heap vituperation upon us, and incidentally to state that something like a million dollars was left behind, but hidden.

“For the sake of my son and daughter, I undertook to recover this money. I consulted attorneys, private detectives, and in fact exhausted every possible method. I ascertained beyond question that the money was not in a bank anywhere; and hardly think he would have left it there, because of course, if he had, even with a will disinheriting us, the law would have turned it over to us. He had no safe deposit vault as far as one month’s close search revealed, and the money was not hidden in the house or grounds. He stated on his death bed that it was in bonds and gold, and that we should never find it. He was just vindictive enough not to destroy it, but to leave it somewhere, believing we should never find it. Where did he hide it?”

The Thinking Machine sat silent for several minutes, with his enormous yellow head tilted back, and slender fingers pressed together. “The house and grounds were searched?” he asked.

“The house was searched from cellar to garret,” was the reply. “Workmen, under my directions, practically wrecked the building. Floors, ceilings, walls, chimney, stairs — everything — little cubby holes in the roof, the foundation of the chimney, the pillars, even the flag stones leading from the gate to the door — everything was examined. The joists were sounded to see if they were solid, and a dozen of them were cut through; the posts on the veranda were cut to pieces; and every stick of furniture was dissected — mattresses, beds, chairs, tables, bureaus — all of it. Outside in the grounds the search was just as thorough. Not one square inch but what was overturned. We dug it all up to a depth of ten feet. Still nothing.”

“Of course,” said the scientist at last, “the search of the house and grounds was useless. The old man was shrewd enough to know that they would be searched. Also it would appear that the search of banks and safety deposit vaults was equally useless. He was shrewd enough to foresee that too. We shall, for the present, assume that he did not destroy the money or give it away; so it is hidden. If the brain of man is clever enough to conceal a thing, the brain of man is clever enough to find it. It’s a little problem in subtraction, Dr. Ballard.” He was silent for a moment. “Who was your grandfather’s attending physician?”

“I was. I was present at his death. Nothing could be done. It was merely the collapse consequent upon old age. I issued the burial certificate.”

“Were any special directions left as to the place or manner of burial?”

“No.”

“Have all his papers been examined for a clue as to the possible hiding place?”

“Everything. There were no papers to amount to anything.”

“Have you those papers now?”

Dr. Ballard silently produced a packet and handed it to the scientist.

“I shall examine these at my leisure,” said The Thinking Machine. “It may be a day or so before I communicate with you.”

Dr. Ballard went his way. For a dozen hours The Thinking Machine sat with the papers spread out before him, and the keen, squinting, blue eyes dissected them, every paragraph, every sentence, every word. At the end he arose and bundled up the papers impatiently.

“Dear me! Dear me!” he exclaimed irritably. “There’s no cipher — that’s certain. Then what?”

Devastating hands had wrought the wreck of the little hut where the old man died. Standing in the midst of its litter, The Thinking Machine regarded it closely and dispassionately for a long time. The work of destruction had been well done.

“Can you suggest anything?” asked Dr. Ballard impatiently.

“One mind may read another mind,” said The Thinking Machine, “when there is some external thing upon which there can come concentration as a unit. In other words, when we have a given number the logical brain can construct either backward or forward. There are so many thousands of ways in which your grandfather could have disposed of this money, that the task becomes tremendous in view of the fact that we have no starting point. It is a case for patience, rather than any other quality; therefore, for greater speed, we must proceed psychologically. The question then becomes, not one of where the money is hidden, but one of where that sort of man would hide it.

“Now what sort of man was your grandfather?” the scientist continued. “He was crabbed, eccentric, and possibly not mentally sound. The cunning of a diseased brain is greater than the cunning of a normal one. He boasted to you that the money was in existence, and his last words were intended to arouse your curiosity; to hang over you all the rest of your life and torment you. You can imagine the vindictive, petty brain like that putting a thing safely beyond your reach — but just beyond it — near enough to tantalize, and yet far enough to remain undiscovered. This seems to me to be the mental attitude in this case. Your grandfather knew that you would do just what you have done here; that is, search the house and lot. He knew too that you would search banks and safety deposit vaults, and with a million at stake he knew it would be done thoroughly. Knowing this, naturally he would not put the money in any of those places.

“Then what? He doesn’t own any other property, as far as we know, and we shall assume that he did not buy property in the name of some other person; therefore, what have we left? Obviously, if the money is still in existence, it is hidden on somebody’s else property. And the minute we say that, we have the whole wide world to search. But again, doesn’t the deviltry and maliciousness of the old man narrow that down? Wouldn’t he have liked to remember as a dying thought that the money was always just within your reach, and yet safely beyond it? Wouldn’t it have been a keener revenge to have you dig over the whole place, while the money was hidden just six feet outside in a spot where you would never dig? It might be sixty, or six hundred, or six thousand. But then we have the law of probability to narrow those limits; so —”

Professor Van Dusen turned suddenly and strolled across the uneven ground to the property line. Walking slowly and scrutinizing the ground as he went, he circled the lot, returning to the starting point. Dr. Ballard had followed along behind him.

“Are all your grandfather’s belongings still in the house?” asked the scientist.

“Yes, everything just as he left it; that is, except his dog an............