ding to the
professor, who was using the telescope at the time, and shot their
deadly rays toward our world. We were too late to prevent the renewal of
hostilities!

Another and another streak of green light followed and we knew that
great havoc was being wrought back home. But these served to locate the
enemy's position definitely and we immediately set about to draw nearer.
We were still somewhat on the dark side of the object, which had
prevented our seeing it. Now we swung about so that it was plainly
visible. And, what a strange appearance it presented, out here in space!

Fully fifteen miles in diameter, it was a huge doughnut, a great ring of
tubing with a center-opening that was at least eighty per cent of its
maximum diameter. There it hovered, sending out those deadly missiles in
a continuous stream toward our poor world. As we approached the weird
space flier, we saw that a number of objects floated about within the
great circle of its inner circumference. The NY-18, the SF-61 and the
SF-22, without doubt! The theory of Hart's was correct in every detail.

* * * * *

We were still at about ten miles distance from the great ring and the
streaking light pencils were speeding earthward at the rate of one a
minute now. There was no time to lose. Already there was more
destruction on its way than had been previously wrought--several times
over.

Hart was sighting along a tiny tube that projected into the forward
partition and he maneuvered the _Pioneer_ until she was nose on to the
great ring. He pulled a switch and there came a purring that was
entirely new. A row of huge vacuum tubes along the wall lighted to vivid
brilliancy and a throbbing vibration filled the artificial air of the
cabin.

He pulled a small lever at the side of the tube and the vessel rocked to
the energy that was released from those vacuum tubes. The thin rod which
had been installed at the _Pioneer's_ nose burst into brilliant
flame--orange tinted luminescence that grew to a sphere of probably ten
feet in diameter. Then there was a heavy shock and the ball of fire left
its position and, with inconceivable velocity, sprang straight for the
side of the great ring. It was a fair hit and, when the weird missile
found its mark, it simply vanished--swallowed up in the metal walls of
the monster vessel. For a moment we thought nothing was to result. Then
we burst into shouts of joy, for a great section of the r