"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. "Oh, it's not proof; it's idle hypothesis," admitted Darrow. "We shall have to test it. But let's go on with it, anyway, and see how it works out." "What's McCarthy got to do with it?" demanded Helen. "That's so, you aren't in touch there." Darrow sketched briefly the situation as it affected the boss. Helen's eyes were shining with interest. "Now," continued Darrow, "having tried out his new power to the limit, our friend would begin to use it only as he needed it. There is now no reason to empty the water-pot entirely. All he wanted to do this morning was to scare McCarthy, and impress the public. He did that in thirty-eight minutes. On the basis of fourteen hours to fill the water-pot, it is evident that he would be rehabilitated, ready for business, in an hour. Therefore, all he is waiting for now is the most effective moment to try out his city-wide experiment of silence. I imagine that will be about six." "Sounds reasonable," admitted Jack. "Reasonable! It's certain!" cried Helen. Darrow smiled. "No, only a wild hypothesis." "It'll scare people to death," observed Jack. "They're scared already; and they're somewhat prepared by the performance this morning. Besides, I don't see yet that human agency is suspected." "Don't you think you'd better warn people what is going to happen, and tell them there's nothing to be frightened of?" pleaded Helen. "No," said Darrow, "I do not. It would confuse the phenomena, and they must be unconfused in order that I can either prove or disprove my hypothesis. If this lasts about two hours, the fact will go far to prove me right. If the next manifestation comes at about ten the next morning, we shall have established a periodicity, at least. But if the man realizes that his existence is suspected, he will purposely vary in order to mix me up." "The next manifestation!" cried Helen. "Then you think they will continue--"