"It was, and it was also adjustable. I could vary the focal point from a few feet to several miles. With that apparatus I could throw a beam of negative heat with a focal point which I could adjust at will. Close to the apparatus, I could obtain a temperature almost down to absolute zero, but at the longer ranges it wasn't so cold, due to leakage into the atmosphere. Even at two miles I could produce a local temperature of three hundred degrees below zero." "What was the source of your cold?" "Liquid helium. Those cylinders contain, or rather did contain, for I expect that Koskoff has emptied them, helium in a liquid state." "Where is your compressor?" * * * * * "I didn't have to use one. I developed a cold light under whose rays helium would liquefy and remain in a state of equilibrium until exposed to light rays. Those cylinders had merely enough pressure to force the liquid out to where the sun could hit it, and then it turned to a gas, dropping the temperature at the first focal point of the reflector to absolute zero. When I had this much done, Koskoff and I packed the whole apparatus here and were ready for work. "We were on the path of the transcontinental air mail, and I bided my time until an especially valuable shipment was to be made. My plans, which worked perfectly, were to freeze the plane in midair and then rob the wreck. I heard of the jewel shipment the T. A. C. was to carry and I planned to get it. When the plane came over, Koskoff and I brought it down. The unsuspected presence of another plane upset us a little, and I started to bring it down. But we had been all over this country and knew there was no place that a plane could land. I let it go on in safety." "Thank you," replied Carnes with a grimace. "We robbed the wreck and we found two packets, one the jewels I was after, 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 someone to come. Had we followed our original plans, we would have been miles from here before you arrived.