"And let our hidden antagonist know we are aware of his existence?"

inquired Darrow.

"Anything else?"

"No--yes. Buy a gun. If I bring you into any trouble, I'll see you clear.

You understand?"

"I do."

"I rely on your being game."

"To the limit," said Jack. "Here comes your friend. Won't this arrest ball things up? Shall I rustle bail?"

"No," said Darrow. "I want to think. All I need is all the papers. I'll be out by ten to-morrow morning, sure."

"Why are you sure of that?"

"_Because by that hour McCarthy will have disappeared_," said Percy Darrow.

The man in the gray suit, having finished his scrutiny, lounged forward.

"You are Mr. Darrow," he stated.

"Sure I am, my amiable but obvious sleuth," drawled that young man. "Lead on." He nodded a farewell to Jack, and linked his arm in that of the officer. After a few moments he burst into an irrepressible chuckle.

"The fat, thick-necked, thick-witted, old fool!" said he.

CHAPTER VIII

PERCY DARROW'S THEORY

Percy Darrow in the police station, where he had been a.s.signed an unused office instead of a cell, amused himself reading the newspapers, of which he caused to be brought in a full supply. Theories had begun to claim their share of the s.p.a.ce which, up to now, the fact stories had completely monopolized. Darrow, his feet up, a cigarette depending from one corner of his mouth, read them through to the end. Then he indulged the white walls of his little apartment with one of his slow smiles. The simplest of the theories had to do with comets. The most elaborate traced out an a.n.a.logy between the "blind spot" in vision and a "point of rest" in physical manifestations--this "point of rest" had just now happened to drift to a crowded center, and so became manifest.

"Ingenious but fantastic youth," was Percy Darrow's tribute to the author, Professor Eldridge of the university.

The "human-interest" stories of both the evening before and those in the extras describing the latest freak in the Atlas Building, Darrow pa.s.sed over with barely a glance. But certain figures he copied carefully into his notebook. When he had found all of these, and had transcribed them, they appeared about as follows:

Atlas--Wednesday, 5:25. 3:00 (about): 9 hr. 35 min.

General--Thursday, 6:00. 7:56 (exact): 1 hr. 56 min.

Atlas--Friday, 10:10. 10:48 (exact): 38 min.

On the basis of these latter figures he made some calculations which, when finished, he looked on with doubtful satisfaction.

"Need more statistics," said he to himself, "before I can pose as a prophet. Just now I'm merely a guesser."

By now it was afternoon. An official came to announce visitors, and a moment later Helen and her brother came in. As Percy's case was merely one of detention, or for some other obscurer reason, known only to those who took their orders from McCarthy, the three were left alone to their own devices.

At the sight of Helen's trim tailor-clad figure Percy's expression brightened to what, in his case, might almost be called animation. He swept aside the acc.u.mulation of papers, and made room for both. After the first greetings and exclamations, Helen demanded to know particulars and prospects.

"All right, I'll tell you," agreed Darrow. "I'm thought out; and I want to hear it myself."

Jack looked about him uneasily.

"Is it wise to talk here?" he asked. "I don't doubt they have arrangements for overhearing anything that is said."

"I don't think they care what we say," observed Darrow. "They are merely detaining me on some excuse or another that I haven't even taken the trouble to inquire about."

"That must astonish them some," said Jack.

"And if they do overhear, I don't much care. Now," said he, turning to Helen, "we have here three strange happenings comprising two phenomena--the cutting off of the electricity, first in the Atlas Building, second in the city at large; and the cutting off of sound in the Atlas. Although we are, of course, not justified in generalizing from one instance, what would you think by a.n.a.logy would be the next thing to expect?"

"That sound would be cut off in the city," said Helen; "but Jack has already delivered me your warning or advice," she added.

"Precisely. Now as to theories of the ultimate cause. Naturally this must have been brought about either by nature or by man. If by nature, it is exceedingly localized, not to say directed. If by man, he must have in some way acquired unprecedented powers over the phenomena of electricity and sound. These he can evidently, at will, either focus, as on the Atlas Building, or diffuse, as over the city. For the moment we will adopt the latter hypothesis."

"That it is a man in possession of extraordinary powers," said Helen, leaning forward in her interest. "Go on."

"We have, completed, only the phenomena of electricity," continued Darrow; "the phenomena of sound remain to be completed. We observe as to that (a)"--he folded back his forefinger--"the Atlas manifestation lasted about nine and a half hours; and (b)"--he folded his middle finger--"the city manifestation was a little less than two hours."

"Yes," cried Jack, "but then this second--"

"One minute," interrupted Darrow; "let me finish. Now, let us place ourselves in the position of a man possessed of a new toy, or a new power which he has never tried out! What would he do?"

"Try it out," said Jack.

"Certainly; try it out to the limit, to see just what it could do in different circ.u.mstances. Now, take the lapses of time I have mentioned, and a.s.sume, for the sake of argument, that these powers are limited."

"Just how do you mean--limited?" asked Helen.

"I mean exhaustible, like a watering-pot. You can water just so much, and then you have to go back and fill up again. In that case, we can suppose this man's stream will last nine hours and a half when he dribbles it down on one spot, like the Atlas Building; but it will empty itself in about two hours when he turns her upside down over a whole city. There remains only the length of time necessary to refill the water-pot to round out our hypothesis. That is something more than nine hours and something less than fifteen."

"How do you get those figures?" demanded Jack.

"The Unknown is anxious, after the Atlas success, to try out his discovery on the larger scale. He will naturally do so at the first opportunity after his water-pot is refilled. But he wishes to do so at the first effective opportunity. What is the most effective moment? The rush hours.

What are the rush hours? From eight to ten, and at six. Since he did not pull off his show in the morning, we are fairly justified in concluding, tentatively, that the water-pot was not full by then, and, as the Atlas phenomena subsided at three of the morning before, the inference is obvious."

"But isn't the most effective time at night, anyway, on account of the lights?" asked Jack.

"Good boy!" approved Darrow. "He might have waited for that. But the city-wide phenomena ceased at eight the night before; and the Atlas sound phenomena did not occur until ten the next morning--fourteen hours. Now, the most effective time to scare McCarthy was any time after nine.

McCarthy arrives as the clock strikes."

Jack shook his head.