or receiver, is strikingly apparent when it is realized that
every square inch of an imaginary plane bisecting the unlocated beam
would have to be explored with a receiving battery in order to locate
the beam itself.

A practical compromise between the spherical or universal broadcast
senders and receivers on the one hand, and the single line batteries on
the other, is the _multi-facet battery_. Another, and more practical
device particularly for distance work, is the _window-spherical_. It is
merely an ordinary spherical battery with a shielding shell with an
opening of any desired size, from which a directionally controlled beam
may be emitted in different forms, usually that simply of an expanding
cone, with an angle of expansion sufficient to cover the desired
territory at the desired point of reception.

CHAPTER VI

An Unequal Duel

But to return to my narrative, and my _swooper_, from which I was gazing
at the interior of the Han ship.

This ship was not unlike the great dirigibles of the Twentieth Century
in shape, except that it had no suspended control car nor gondolas, no
propellers, and no rudders, aside from a permanently fixed
double-fishtail stabilizer at the rear, and a number of "keels" so
arranged as to make the most of the repeller ray airlift columns.

Its width was probably twice as great as its depth, and its length about
twice its width. That is to say, it was about 100 feet from the main
keel to the top-deck at their maximum distance from each other, about
200 feet wide amidship, and between 400 and 500 feet long. It had in
addition to the top-deck, three interior decks. In its general curvature
the ship was a compromise between a true streamline design and a
flattened cylinder.

For a distance of probably 75 to 100 feet back of the nose there were no
decks except that formed by the bottom of the hull. But from this point
back the decks ran to within a few feet of the stern.

At various spots on the hull curvature in this great "hollow nose" were
platforms from which the crews of the _dis_ ray generators and the
_electronoscope_ and _electronophone_ devices manipulated their
apparatus.

Into this space from the forward end of the center deck, projected the
control room. The walls, ceiling and floor of this compartment were
simply the surfaces of _viewplates_. There were no windows or other
openings.

The operation officers within the control room, so far as their vision
was c