and the other a sealed packet, which proved to contain certain War Department plans. That was when I learned who Koskoff was. I had hired him in San Francisco as a good mechanic who had no principles. He was to get one-fourth of the loot. When we found these plans, he told me who he was. He was really a Russian secret agent and he wanted to deliver the plans to Russia. I may be a thief and a murderer, but I am not yet ready to betray my country, and I told him so. He offered me almost any price for the plans; but I wouldn't listen. We had a serious quarrel, and he overpowered me and bound me.
"WE had a radio set here and he called San Francisco and sent some code message. I think he was waiting here for some one to come. Had we followed our original plans, we would have been miles from here before you arrived.
"He had me bound and helpless, as he thought, but I worked my bonds a little loose. I didn't let him know it, for I knew that the plane I had let get away would guide a party here and I thought I might be able to help out. When you came and attacked the house, I worked at my bonds until they were loose enough to throw off. I saw Koskoff start my cold apparatus to working and then he quit, because he ran out of helium. When be started shooting again, I worked out of my bonds and tackled him.
"He was a better man than I gave him credit for, or else he suspected me, for about the time I grabbed him he whirled and struck me over the head with his gun barrel and tore my face open. The blow stunned me; and when I came to, I was thrown into this corner. I meant to have another try at it, but I guess you rushed him too fast. He turned and ran for the tunnel, but as he did so, he shot me through the body. I guess I didn't look dead enough to suit him. You gentlemen broke open the door and came in. That's all."
"Not by, a long shot, it isn't," exclaimed Dr. Bird. "Where is that cold light apparatus of yours?"
"In the tunnel."
"How do you get into it?"
"If you will open that cupboard on the wall, you'll find an open knife switch on the wall. Close it."
DR. BIRD found the switch and closed it. As he did so the cabin rocked on its foundations and both Carnes and Walter were thrown to the ground. The thud of a detonation deep in the earth came to their ears.
"What was that?" cried the doctor.
"That," replied Smith with a wan smile, "was the detonation of two hundred pounds of T.N.T. When you dig down into the underground cave where we used the cold light apparatus, you will find it in fragments. It was my only child, and I'll take it with me."
As he finished his head slumped forward on his chest. With an exclamation of dismay Dr. Bird sprang forward and tried to lift the prostrate form.
In an agony of desire the Doctor tightened his grip on the dying man's shoulder. But Smith collapsed into a heap. Dr. Bird bent forward and tore open his shirt and listened at his chest. Presently he straightened up.
"He is gone," he said sadly, "and I guess the results of his genius have died with him. He doesn't strike me as a man who left overmuch to chance. Carnes, is your case completed?"
"Very satisfactorily. Doctor. I have both of the lost packets."
"All right, then, come back to the wreck and help me pack my burros. I can make my way back to Fallon without a guide."
"Where are you going. Doctor?"
"That, Carnes, old dear, is none of your blankety blanked business. Permit me to remind you that I am on my vacation. I haven't decided yet just where I lam going, but I can tell you one thing. It's going to be some place where you can't call me on the telephone."
