"I'll believe you, Doctor," replied the detective; "but I'd believe you just as quickly if you swore that the moon was made of cream cheese made from the milk taken from the milky way. One would be just as understandable to me as the other." * * * * * They were interrupted by the entrance of a waiter who bore a huge pot of steaming coffee. Dr. Bird's eyes lighted up as a cup was poured. Carnes knew enough not to interrupt while the doctor poured and drank eight cups of the strong black fluid. As he drank, the lines of fatigue disappeared from the scientist's face. He sat up as fresh as though he had not been working at high pressure the entire night. "Dr. Fisher tells me that the amount of caffeine I drink would kill a horse," he said with a chuckle; "but sometimes it is needed. I feel better now. Let's get to work." "What shall we do?" "Despite Saranoff's words, it must be possible to trace him. He is undoubtedly releasing his energy from some form of subterranean borer, and such a thing can be located. The energy he uses must set up electrical disturbances which instruments will detect. I have had work started on a number of ultra-sensitive wave detectors which will record any wave-length from zero to five millimeters. We'll send them to various points along the seacoast. They ought to pick up the stray waves from the energy he is using to blast a path through the earth. I'm not going to bother with the waves from his motor; they may be of any wave-length, and there would be constant false alarms. I have another idea." "What is it?" "I am judging Saranoff from his previous actions. You remember that he used a submarine in that alien-smuggling scheme the Coast Guard broke up, and also when he loosed that sea monster on the Atlantic shipping? He seems to be rather fond of submarines." "Well?" * * * * * "The amount of energy he uses must be almost inconceivable," Dr. Bird went on. "He can hardly carry an amount of fuel which will enable him to bore underground for very many miles, Charleston is on the coast. I have an idea that he uses a submarine to transport his borer from point to point. After using the borer he must return to the submarine for recharging and transportation to the point where he plans to strike next. I already have two hundred planes scouring the sea looking for such a craft." "Where do you expect him to strike next?" "I have no idea. New York and Washington will undoubtedly be targets eventually, but neither of them may be next. Meanwhile, would you like to do a little more flying?" "Surely." "A plane is waiting for us at Langley Field. I want to look over the coast in the vicinity of Charleston Harbor and some of the sounds near there. If he is using a sub, he must have a base somewhere." * * * * *