study.
We know a little of the sub-rays, which we use every day, and
practically nothing of the infra-rays. Some time ago I developed a
detector for infra-rays, which come to us from outer space in small
quantities and which are also liberated by our power-plants. It has been
regarded as a scientific curiosity only, but this day it proved of real
value. This instrument in my hand is such a detector. At normal impacts
of infra-rays its light is blue, as you see it now. Some time before the
warning sounded it turned a brilliant red, indicating that an intense
source of infra-rays was operating in the neighborhood. By plotting
lines of force I located the source as being in the air of the council
hall, almost directly above the table of state. Therefore the carrier
wave must have come through our whole system of screens without so much
as giving an alarm. That fact alone proves it to have been an infra-ray.
Furthermore, it carried through those screens and released in the
council room a system of forces of great complexity, as is shown by
their ability to broadcast from those pure forces without material aid a
modulated wave in the exact frequency required to energize our general
speakers.

"As soon as I perceived these facts I threw about the council room a
screen of force entirely impervious to anything longer than ultra-rays.
The warning continued, and I then knew that our fears were only too well
grounded--that there is in this Galaxy somewhere a race vastly superior
to ours in science and that our destruction is a matter of hours,
perhaps of minutes."

"Are these ultra-rays, then, of such a dangerous character?" asked the
general. "I had supposed them to be of such infinitely high frequency
that they could be of no practical use whatever."

* * * * *

"I have been trying for years to learn something of their nature, but
beyond working out a method for their detection and a method of possible
analysis that may or may not succeed I can do nothing with them. It is
perfectly evident, however, that they lie below the level of the ether,
and therefore have a velocity of propagation infinitely greater than
that of light. You may see for yourself, then, that to a science able to
guide and control them, to make them act as carrier waves for any other
desired frequency--to do all of which the Overlord has this day shown
himself capable--they should theoretically afford weapons before which
o