mic bombs, only to see them exploded
harmlessly by neutron guns, or caught in the magnetic screen. Gamma ray
bombs were as useless. Again the beam of disintegrating force was turned
on--

The present opponent was not a ship. It was an IP defense station,
equipped with everything Solarian science knew, and the dome was an
eight-foot wall of tungsten-beryllium. The eight feet of solid,
ultra-resistant alloy drank up that crumbling beam, and liked it. The
wall did not fail. The men inside the fort jerked and quivered as the
strange beam, a small, small fraction of it, penetrated the eight feet
of outer wall, the six feet or so of intervening walls, and the mercury
atostor reserves.

"Concentrate all those UV beams on one spot, and see if you can blast a
hole in him before he shakes it loose," ordered the ray technician.
"He'll wiggle if you start off with the beam. Train your sights on the
nose of that first ship--when you're ready, call out."

"Ready--ready--" Ten men replied. "Fire!" roared the technician. Ten
titanic swords of pure ultra-violet energy, energy that practically no
unconditioned metal will reflect to more than fifty per cent, emerged.
There was a single spot of intense incandescence for a single hundredth
of a second--and then the energy was burning its way through the inner,
thinner skins with such rapidity that they sputtered and flickered like
a broken televisor.

One hundred and twenty-nine ships retreated hastily for conference,
leaving a gutted, wrecked hull, broken by its fall, on Europa.
Triumphantly, the Europa IP station hurled out its radio message of the
first encounter between a fort and the Miran forces.

Most important of all, it sent a great deal of badly wanted information
regarding the Miran weapons. Particularly interesting was the fact that
it had withstood the impact of that disintegrating ray.

VIII

Grimly Buck Kendall looked at the reports. McLaurin stood beside him,
Devin sat across the table from him. "What do you make of it, Buck?"
asked the Commander.

"That we have just one island of resistance left on the Jovian worlds.
And that will, I fear, vanish. They haven't finished with their arsenal
by any means."

"But what was it, man, what was it that ruined those ships?"

"Vibration. Somehow--Lord only knows how it's done--they can project
electric fields. These projected fields are oscillated, and they are
tuned in with some parts of the ship. I suspect they a