of water conduit was no impossibility.

Then they were ready. Mars Center came first. Automatic devices kept the
aim exact, as the first of the magnetic bombs started down. At
five-second intervals they were projected outward, invisible globes of
concentrated magnetic energy, undetectable in space. Seven seconds
passed before the first became dimly visible in the thin air of Mars. It
floated down, it would miss the fort it seemed--so far to one side--
Abruptly it turned, and darted with tremendously accelerating speed for
the great magnetic field of the fort. With a vast blast of light, it
exploded. Five seconds later a second exploded. And a third.

Mars Center signaled scoffingly that the bombs were all being stopped
dead in the magnetic atmosphere, after the bombardment had been
witnessed from Earth and Luna. An hour later they gave a report that
they were concentrated magnetic fields of energy that would be rather
dangerous--if it weren't that they couldn't even stand into the magnetic
atmosphere. Three hours later Mars Center reported that they contained
considerably more energy than had at first been thought. Further, which
they had not carefully considered at first, they were taking energy with
them! They were taking away about an equal amount of energy as each blew
up.

It was only a half-hour after that that the men at Mars Center realized
perfectly what it meant. Their power was being drained just a little bit
better than twice as fast as they generated during the day--and since
Phobos spun so swiftly across the sky.

Deenmor got the attack just about the time Mars Center was released.
Deenmor immediately began seeking for the source of it. Somewhere on
Phobos--but where?

The Mirans were experts at camouflage. Deenmor Station, realizing the
menace, immediately rayed the "projector." They tore up a great deal of
harmless rock with their huge UV rays. But the bomb device continued to
throw one bomb each five seconds.

When Deenmor operated from Phobos' position, Mars Center was exposed to
the deadly, constant drain. A day or two later, the bombs were coming
one each second and a half, for more ships had joined in the work on
Phobos.

Gresth Gkae saw the work was going nicely. He knew that now it was only
a question of time before those magnetic shields would fail--and then
the whole fort would be powerless. Maybe--it might be a good idea, when
the forts were powerless to investigate instead of blowing