m 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 r