ell at even
intervals, through the rent in the upper surface. The ram had already
crushed through two thicknesses of metal, and was battering at the inner
layer.

The inside section was more like glass than metal and dim light passed
through, but the outer layers were opaque. When the huge ram disappeared
from the glow of light it left a gaping hole where it had been. It was
of material they had never seen and glistened with a brownish hue. It
appeared to shorten and expand in diameter, each time it struck the
surface.

For a moment they hesitated, trying to decide the best means of attack.
Whatever animated the ram was above their vision, and they had to be
close to the opening to see it.

Each time the shiny object descended, the dome vibrated beneath their
feet. As long as the vibration remained they were safe, but when it felt
like a thud--the metal would be cracking!

Thousands of helpless people were depending on the action of earthmen,
for their future existence. They seemed to think that it was only
necessary to _tell_ their troubles to these amazing strangers, to have
them solved. Stories about the use of water to drive the space ship, had
circulated throughout the cities, crediting the newcomers with
superhuman powers.

As the little party crept nearer, they separated, to approach the
opening from every direction. Dick was to fire first--if he saw anything
to shoot at! It might be a powerful machine, clamped to the outer
surface, instead of a being that could be injured. The glass globes of
the masks were clouding with moisture, and it was hard to see.

A thud came, that didn't vibrate quite as much, and the men could feel
the hair on their necks stiffen. It was now or never, and Dick fired
although he was still several feet from the opening. He fired at the
topmost section of the ram, hoping it might stop the hammering for a
moment even if it didn't injure the equipment. Two more shots rang out,
before the object could deliver another blow.

_It was alive!_ The heavy ram _jumped_ from the shock of the bullets,
curving convulsively to one side of the opening. Then it drew back out
of sight.

CHAPTER VIII

_Battle with a Monster_

Minutes passed, while the earthmen hardly dared breathe. Their ebbing
heartbeat seemed to almost echo in their breasts. Then the object
appeared at the opening, hesitated, and was thrust in!

_The hammer was a head!!!_ It swayed back and forth, like the head of