"Good work!" somebody cried. They crowded about, keenly interested in this new method of man-hunting. Only Darrow, tipped back in his chair against the wall, seemed unexcited. To Jack's whispered question he shook his head. "It's ingenious," he acknowledged, "but he's on the wrong track." That was as far as he would explain, and soon dropped into a slight doze. Throughout the greater part of the night the experiment continued. Battery by battery the sending power of the instrument was weakened. Mile by mile the special train drew nearer until, by catching the prearranged signal, it determined just how far the new sending reached. Then Simmons tried Monsieur X. As the latter invariably answered, it was, of course, evident that he remained still in the narrowing zone of communication. It was fascinating work, like the drawing of a huge invisible net. The reporters on the morning papers mastered only with difficulty their inclination to stay. They had to leave before their papers went to press, but were back again in an hour, unwilling to lose a moment of the game. A tension vibrated the little office. Only Percy Darrow dozed alone in the corner, leaning back in his wooden armchair. At near four o'clock in the morning Simmons raised his head after a long bout of calling to announce that he could get no reply from Monsieur X. "He's got tired of your fool messages," remarked the _Register_ man. "And I don't wonder! Guess he's gone to bed." Eldridge said nothing, but replaced the Leyden jar he had but just removed. "Try one," said he. "I get him," reported Simmons, after a moment. "Send him anything plausible and reassuring," commanded Eldridge hastily. He turned to his small and attentive audience in triumph. "Thus, gentlemen," he announced, "we have proven conclusively that our man is located between forty and fifty miles from New York. If we draw two circles, with this building as center, the circumference of one of which is fifty, the other forty miles away, we define the territory within which the malefactor in question is to be found." The people in the room crowded close about the table to examine the map upon which Professor Eldridge had drawn the circles. "There's an awful lot of country--some of it pretty wild," objected the _Bulletin_ man. "It will be a long job to hunt a man down in that territory." "Even if it were as extensive a task as a hasty review of the facts might indicate," stated Eldridge, "I venture to assert that enough men would be forthcoming to expedite such a search. But modifying circumstances will lighten the task." "How's that?" asked the _Banner_ man, speaking for the others' evident interest.