"We'll have the doctor here in a few minutes now," said Carnes to the Colonel. "It might be a good plan to send a motorcycle out along the Charleston road to bring him in. We don't want the guards to delay him." The colonel gave an order and a motorcycle shot off down the road. In half an hour it came sputtering back with a huge Cadillac roaring in its wake. The car drew up and stopped. From it descended two men. The first was a small, wizened figure with heavy glasses. What hair age had left to him was as white as snow. The second figure, which towered over the first, was one to merit attention anywhere. * * * * * Dr. Bird was as light on his feet and as quick and graceful as a cat, but there was nothing feline about his appearance. He stood well over six feet in his stockings and tipped the beam close to the two hundred mark. Not one ounce of fat was on his huge frame. So fine was he drawn that unless one looked closely he would never suspect the weight of bone and muscle that his unobtrusive tweed suit covered. Piercing black eyes looked out from under shaggy brows. His face was lean and browned, and it took a second glance to realize the tremendous height and breadth of his forehead. A craggy jutting chin spoke of stubbornness and the relentless following up of a line of action determined on. His head was topped with an unruly shock of black hair which he tossed back with a hand that commanded instant attention. His hands were the most noteworthy thing about the famous Bureau scientist. Long slender hands, they were, with slim tapering fingers--the hands of an artist and a dreamer. The acid stains that marred them could not hide their slim beauty, yet Carnes knew that those hands had muscles like steel wire and that the doctor boasted a grip that could crush the hand of a professional wrestler. He had seen him tear a deck of playing cards in half and, after doubling, again in half, with as little effort as the ordinary man would use in tearing a bare dozen of the cards. As he climbed out of the car his keen black eyes swept around in a comprehensive glance. Carnes, trained observer that he was, knew that in that one glance every essential detail which it had taken him an hour to place had been accurately noted and stored away in the doctor's mind. He came forward to the detective. "Has anything happened since you telephoned me?" was his first question. "Nothing, Doctor. I followed your instructions and also assembled a crew of men with excavating tools." "You're improving, Carnes. This is Dr. Lassen. This is a little out of your line. Doctor, but you may see something familiar. What does it look like to you?" "Not like an earthquake, Bird, at all events. Offhand I would say that a huge cavern had been washed in the earth and the ground had caved in." "It looks that way. If you are right, we should find running water if we dig deep enough. Have you been down in the hole, Carnes?" "No, Doctor."