"Go bring the body in, Carnes," exclaimed the doctor. "I'll take care of the chap inside." "Did you get him?" asked the voice eagerly, as the doctor stepped inside. "He's dead all right," replied the doctor grimly. "Who the devil are you, and what are you doing here?" "There is a light switch on the left of the door as you come in," was the reply. Dr. Bird found the switch and snapped on a light. He turned toward the corner from whence the voice had come and recoiled in horror. Propped in the corner was the body of a middle-aged man, daubed and splashed with blood which ran from a wound in the side of his head. "Good Lord!" he ejaculated. "Let me help you." "There's not much use," replied the man rather faintly. "I am about done in. This face wound doesn't amount to much, but I am shot through the body and am bleeding internally. If you try to move me, it may easily kill me. Leave me alone until your partners come." The doctor drew a flask of brandy from his pocket and advanced toward the corner. "Take a few drops of this," he advised. With an effort the man lifted the flask to his lips and gulped down a little of the fiery spirit. A sound of tramping feet came from the outside and then a thud as though a body had been dropped. Carnes and Walter entered the cabin. "He's dead as a mackerel," said Carnes in answer to the doctor's look. "Walter got him through the neck and broke his spinal cord. He never knew what hit him." "The plans?" came in a gasping voice from the man in the corner. "We got them, too," replied Carnes. "He had both packets inside his coat. They have been opened, but I guess they are all here. Who the devil are you?" "Since Koskoff is dead, and I am dying, there is no reason why I shouldn't tell you," was the answer. "Leave that brandy handy to keep up my strength. I have only a short time and I can't repeat. * * * * * "As to who I am or what I was, it doesn't really matter. Koskoff knew me as John Smith, and it will pass as well as any other name. Let my past stay buried. I am, or was, a scientist of some ability; but fortune frowned on me, and I was driven out of the world. Money would rehabilitate me--money will do anything nowadays--so I set out to get it. In the course of my experimental work, I had discovered that cold was negative heat and reacted to the laws which governed heat." "I knew that," cried Dr. Bird; "but I never could prove it." "Who are you?" demanded John Smith. "Dr. Bird, of the Bureau of Standards." "Oh, Bird. I've heard of you. You can understand me when I say that as heat, positive heat is a concomitant of ordinary light. I have found that cold, negative heat, is a concomitant of cold light. Is my apparatus in good shape outside?" "The reflector is smashed." "I'm sorry. You would have enjoyed studying it. I presume that you saw that it was a catenary curve?" "I rather thought so."