"In two hours, Doctor. A car is waiting for us downstairs and I have reservations booked for both of us on the Southern to-night. I knew that you were coming; in fact, the request for your services had been approved before I came here to see you." Dr. Bird rapidly divested himself of his laboratory smock and took his coat and hat from a cupboard. "I hope you realize, Carnsey, old dear," he said as he followed the operative out of the building, "that I have a real fondness for your worthless old carcass. I am leaving the results of two weeks of patient work alone and unattended in order to keep you out of trouble, and I know that it will be ruined when I get back. I wonder whether you are worth it?" "Bosh!" retorted Carnes. "I'm mighty glad to have you along, but you needn't rub it in by pretending that it is affection for me that is dragging you reluctantly into this mess. With an adventure like this ahead of you, leg-irons and handcuffs wouldn't keep you away from Mammoth Cave, whether I was going or not." It was late afternoon before Dr. Bird and Carnes dismounted from the special train which had carried them from Glasgow Junction to Mammoth Cave. They introduced themselves to the major commanding the guard battalion which had been ordered down to reinforce the single company which had borne the first brunt of the affair, and then interviewed the guards who had been routed by the unseen horror which was haunting the famous cave. Nothing was learned which differed in any great degree from the tale which Carnes had related to the doctor in Washington, except that the officer of the day who had investigated the last attack failed to entirely corroborate the smell of musk which had been reported by the other observers. "It might have been musk, but to me it smelled differently," he said. "Were you ever near a rattlesnake den in the west?" * * * * * Dr. Bird nodded. "Then you know the peculiar reptilian odor which such a place gives off. Well, this smell was somewhat similar, although not the same by any manner of means. It was musky all right, but it was more snake than musk to me. I rather like musk, but this smell gave me the horrors." "Did you hear any noises?" "None at all. The men describe some rather peculiar noises and Sergeant Jervis is an old file and pretty apt to get things straight, but they may have been made by the men who were in trouble. I saw a man caught by a boa in South America once, and the noises he made might very well have been described in almost the same words as Jervis used." "Thanks, Lieutenant," replied the Doctor. "I'll remember what you have told me. Now I think that we'll go into the cave." "My orders are to allow no one to enter, Doctor." "I beg your pardon. Carnes, where is that letter from the Secretary of War?" Carnes produced the document. The lieutenant examined it and excused himself. He returned in a few moments with the commanding officer.