fore be compelled to develop that band. The director must, of
course, have a full equatorial mounting, with circles some two hundred
and fifty feet in diameter. Must your projector tube be longer than
that, for correct design?"

"That length will be ample."

"The mounting must be capable of rotation through the full circle of arc
in either plane, and must be driven in precisely the motion required to
neutralize the motion of our planet, which, as you know, is somewhat
irregular. Additional fast and slow motions must, of course, be provided
to rotate the mechanism upon each graduated circle at the will of the
operator. It is my idea to make the outer supporting tube quite large,
so that you will have full freedom with your inner, or projector tube
proper. It seems to me that dimensions X37 B42 J867 would perhaps be as
good as any."

"Perfectly satisfactory. You have the apparatus well in mind."

"These things will consume some time. How soon will you require this
mechanism?" asked Caslor.

"We also have much to do. Two periods of labor, let us say: or, if you
require them, three."

"It is well. Two periods will be ample time: I was afraid that you might
need it today, and the work cannot be accomplished in one period of
labor. The mounting will, of course, be prepared in the Area of
Experiment. Farewell."

"You aren't going to build the final projector here, then?" Seaton asked
as Caslor's flier disappeared.

"We shall build it here, then transport it to the Area, where its
dirigible housing will be ready to receive it. All mechanisms of that
type are set up there. Not only is the location convenient to all
interested, but there are to be found all necessary tools, equipment and
material. Also, and not least important for such long-range work as we
contemplate, the entire Area of Experiment is anchored immovably to the
solid crust of the planet, so that there can be not even the slightest
vibration to affect the direction of our beams of force, which must, of
course, be very long."

He closed the master switches of his power-plants and the two resumed
work where they had left off. The control panel was soon finished. Rovol
then plated an immense cylinder of copper and placed it in the
power-plant. He next set up an entirely new system of refractory
relief-points and installed additional ground-rods, sealed through the
floor and extending deep into the ground below, explaining as he worked.

"You see, son, we