nd out about the cause of the wreck, Doctor?"

"I don't know what to think. The immediate cause was that everything was
frozen. The plane ran into a belt of cold which froze up the motor and
which probably killed the crew instantly. It was undoubtedly the
aftermath of that cold which you felt when you swooped down over the
wreck."

"It seems impossible that it could have suddenly got cold enough to
freeze everything up like that."

"It does, and yet I am confident that that is what happened. It was no
ordinary cold, Carnes; it was cold of the type that infests interstellar
space; cold beyond any conception you have of cold, cold near the range
of the absolute zero of temperature, nearly four hundred and fifty
degrees below zero on the Fahrenheit scale. At such temperatures, things
which are ordinarily quite flexible and elastic, such as rubber, or
flesh, become as brittle as glass and would break in the manner which
these bodies have broken. An examination of the tissues of the flesh
shows that it has been submitted to some temperature that is very low in
the scale, probably below that of liquid air. Such a temperature would
produce instant death and the other phenomena which we can observe."

"What could cause such a low temperature, Doctor?"

"I don't know yet, although I hope to find out before we are finished.
Cold is a funny thing, Carnes. Ordinarily it is considered as simply the
absence of heat; and yet I have always held it to be a definite negative
quantity. All through nature we observe that every force has its
opposite or negative force to oppose it. We have positive and negative
electrical charges, positive and negative, or north and south, magnetic
poles. We have gravity and its opposite apergy, and I believe cold is
really negative heat."

"I never heard of anything like that, Doctor. I always thought that
things were cold because heat was taken from them--not because cold was
added. It sounds preposterous."

* * * * *

"Such is the common idea, and yet I cannot accept it, for it does not
explain all the recorded phenomena. You are familiar with a searchlight,
are you not?"

"In a general way, yes."

"A searchlight is merely a source of light, and of course, of heat,
which is placed at the focus of a parabolic reflector so that all of the
rays emanating from the source travel in parallel lines. A searchlight,
of course, gives off heat. If we place a lens of the sa