y, as full power of the molecular ray was reached, the entire halo
was buried under a mass of writhing sparks that seemed to leap up into
the air above the man's head, wavering up to extinction. The room was
unbearably hot, despite the molecular ray coolers absorbing the heat of
the air, and blowing cooled air into the room.

Fuller snapped off the ray, and put the pistol on the table beside him.
The halo died, and went out a moment later, and Arcot settled to the
floor.

"This particular suit will stand up against anything the ordinary
commercial sets will give. The system now: remember that the rays are
short electrical waves. The easiest way to stop them is to interpose a
wave of opposite phase, and cause interference. Fine, but try to get in
tune with an unknown wave when it is moving in relation to your center
of control. It is impossible to do it before you yourself have been
rayed out of existence. We must use some system that will automatically,
instantly be out of phase.

"The Hall effect would naturally tend to make the frequency of a wave
through a resisting medium change, and lengthen. If we can send out a
spherical wave front, and have it lengthen rapidly as it proceeds, we
will have a wave front that is, at all points, different. Any entering
wave would, sooner or later, meet a wave that was half a phase out, no
matter what the motion was, nor what the frequency, as long as it lies
within the comparatively narrow molecular wave band. What this
apparatus, or ray screen, consists of, is a machine generating a
spherical wave front of the nature of a molecular wave, but of just too
great a frequency to do anything. A second part generates a condition in
space, which opposes that wave. After traveling a certain distance, the
wave has lengthened to molecular wave type, but is now beyond the
machine which generated it, and no longer affects it, or damages it.
However, as it proceeds, it continues to lengthen, till eventually it
reaches the length of infra-light, when the air quickly absorbs it, as
it reaches one of the absorption bands for air molecular waves, and any
molecular wave must find its half-wave complement somewhere in that
wedge of waves. It does, and is at once choked off, its energy fighting
the energy of the ray screen, of course. In the air, however, the screen
is greatly helped by the fact that before the half-wave frequency is met
in the ray-wedge, the molecular ray is buried in ions, leaving