matically broadcast on an accurate tuning channel to this viewplate
by the automatic mechanism of the projectile. In turn my control board
broadcast the signals which automatically controlled the movements of
the ball.

Above and below the viewplate were the pointers and the swinging needles
which indicated the speed and angle of vertical movement, the altimeter,
the directional compass, and the horizontal speed and distance
indicators.

At my left hand was the lever by which I could set the "eye" for
penetrative, normal or varying degrees of telescopic vision, and at my
right the universally jointed stick (much like the "joy stick" of the
ancient airplanes) with its speed control button on the top, with which
the ball was directionally "pointed" and controlled.

The manipulation of these levers I had found, with a very little
practice, most instinctive and simple.

So, as I have said, I pointed my projectile straight up and let it shoot
to the height of two miles. Then I levelled it off, and shot it at full
speed (about 500 miles an hour with no allowance for air currents) in a
general southwesterly direction, while I eased my controls until I
brought in the telescopic view of Lo-Tan. I centered the picture of the
city on the crossed hairlines in the middle of my viewpoint, and watched
its image grow.

* * * * *

In about fifteen minutes the "string" of air balls was before the city,
and speaking in my ultrophone I gave the order to halt, while I swung
the scope control to the penetrative setting and let my "eye" rove
slowly back and forth through the walls of the city, hunting for a spot
from which I might get my bearings. At last, after many penetrations, I
managed to bring in a view of the head of the shaft at the bottom of
which I knew the tunnels were located, and saw that we were none too
soon, for all the corridors leading toward this shaft were packed with
Hans waiting their turn to descend.

Slowly I let my "eye" retreat down one of these corridors until I
"pulled it out" through the outer wall of the city. There I held the
spot on the crossed hairlines and ordered Number Two Operator to my
control board, where I pointed out to her the exact spot where I desired
a breach in the wall. Returning to her own board, she withdrew her ball
from the "string," and focussing on this spot in the wall, eased her
projectile into contact with it and detonated.

The atomic force of th