"He must be using a ray of some sort, possibly a radium emanation," he muttered to himself. "That would have no wave motion and might accomplish the result, although I would expect the exact opposite from it. The first thing to do is to examine that powder with a spectroscope and see if I can get a clue to the electronic arrangement." * * * * * When Carnes arrived at the Bureau of Standards at dawn be rubbed his eyes in astonishment. The buildings were lighted up and the grounds swarmed with workmen. Before the buildings were lined up a dozen trucks and twice that many touring cars. A cordon of police held back the curious. Carnes' gold badge won him an entrance and he hurried up the stairs to Dr. Bird's laboratory. The doctor's face was drawn and haggard, but his eyes glowed with a feverish light. Workmen were carrying down huge boxes. "What's up, Doctor?" demanded the detective. "Oh, you got here at last, did you? You're just in time. If you'd been fifteen minutes later, you would have found us gone." "Gone where?" "Out into Maryland in an attempt to stop Saranoff in his progress toward Washington." "Have you found your means of combating him?" "I hope so, although it is not what I started out to get. Did you bring a car as I told you?" "It's waiting below." "Good enough. I'll go in it. Williams, are those projectors all loaded?" "Yes, Dr. Bird. The magnet will be ready to go in five minutes. The electroscopes and the other light stuff are all loaded and ready to move." "You have done well. I'll let you bring the trucks and heavy equipment while I go ahead with the instruments. Take the road out toward Upper Marlboro. If I don't meet you before, stop there for orders." "Very well, Doctor." "Come on, Carnes, let's go." * * * * * He raced down the stairs with the detective at his heels. He went along the line of touring cars and spoke briefly to the drivers. He climbed into the car which Carnes had brought. As it started the other cars fell in behind it. At a speed of forty miles an hour, with a detachment of motorcycle police leading the van, the cavalcade rolled out through the deserted streets of Washington. Once clear of the city, the speed was increased. "Did you persuade the President to leave?" asked the doctor. "There wasn't a chance. The papers panned him so much for following my advice at Charleston that he has turned stubborn. He says that if all the forces of the government can't protect him against one man, he is willing to die." "We've got to save him," said Dr. Bird grimly. "Hello, there's the Chesapeake ahead." The doctor studied the country.