"It will go more than crazy," Wade commented grimly. "This is going to make everyone in this town handling money panic-stricken!" "It is the start of the Invisible Master's rule!" said Grantham solemnly. "From now on no one in New York is safe from him! He is deliberately terrorizing the city, and at the same time enriching himself!" The door opened and President Ellsworth burst inside, his ordinarily genial face twisted with emotion. "Grantham!" he exclaimed. "Have you heard of this latest outrage of this assistant of yours--this Invisible Master?" Grantham nodded somberly. "We've just heard." "But this is horrible!" Ellsworth cried. "To think that Gray, so quiet and sane to all appearances, should become this unseen thief and killer!" "Why should Gray be so crazy after money, anyway?" Wade asked him. "They tell me he was a scientific rather than business type." "I think I can understand it," President Ellsworth said. "Gray has long wanted funds for independent research--even he and Grantham here have been terribly hampered in their work by lack of money. He has seen the millions that are spent each year in this city on luxury and pleasure, has reflected how much good might result to the human race were part of it applied to scientific research, and has started out with this weapon of invisibility to get it!" "You sound almost as though you were in sympathy with him," Wade said. "My dear sir!" Ellsworth was visibly shocked. "I may believe that a fraction of the city's riches would be better applied in research, but I would never condone the murder of helpless clerks to obtain it." "I was only joking," Wade apologized. "Grantham and I think we have found a way to curb the Invisible Master's activities, at least." "Indeed?" asked Ellsworth curiously. "Yes." And Wade explained the idea of the turnstiles, which the President at once approved. A City Terrified "But it seems that will only limit his activities," he said. "Is there no chance of capturing him completely? Are you sure, Grantham, that the projector he stole might not suddenly cease to function and make him visible?" "No chance of that," said Grantham hopelessly. "The batteries in its case are small but enough to keep it running for weeks, at intervals. And since it's Gray that took it, he'll know how to replace them." President Ellsworth nodded. "I suppose so. But he'll have to be captured soon or the city will be in panic." Grantham shook his head. "This second crime is enough to send it into panic, almost, without further aid, Ellsworth. And if the Invisible Master should strike again soon--"