rified by the awful possibilities pictured
by various prominent speakers.

The governments of all foreign powers made haste to disclaim
responsibility for the air attacks or for any attempt at making war on
the United States. News broadcasts failed to mention Hart Jones or the
_Pioneer_, since the mission had been kept secret. The phenomenon of the
rays and the roaring column of light had been observed from many points
on this occasion and there was no longer any doubt as to the nature of
the terror as visible to the eye, though theories as to the action and
source of the rays conflicted greatly and formed the basis of much
heated discussion.

Eventually the advancing dawn reached San Francisco, and with its advent
Hart decided to make a landing in that city so that my bonds could be
delivered.

* * * * *

Jones was apparently a very much mystified and discouraged man. "Jack,"
he said, "it seems to me that this thing is but the beginning of some
tremendous campaign that is being waged against our country by a clever
and powerful enemy. And I feel that our work in connection with the
unraveling of the mystery and overcoming the enemy or enemies is but
begun. It's a cinch that the thing is organized by human minds and is
not any sort of a freak of the elements. Our work is cut out for us, all
right, and I wish you would stick to George and me through the mess.
Will you?"

"Sure," I agreed, readily enough. "After these bonds are delivered I am
free for a month."

"Ha! Ha!" cackled George, without mirth. "A month! We're doggoned lucky
if we get to the bottom of this in a year."

"Nonsense!" snapped Hart, who was considerably upset by the failure to
locate the source of the disastrous rays. "There is nothing supernatural
about this, and anything that can be explained on a scientific basis can
be run to earth in short order. These rays are man-made and, as such,
can be accounted for by man. Our greatest scientists must be put to work
on the problem at once--in fact, they have quite probably been called in
by the government already."

* * * * *

He was maneuvering the _Pioneer_ to a landing on the broad field of the
San Francisco airport. Hundreds of idle planes of all sizes lined the
field, and, unmindful of the earliness the hour, a great crowd was
collected in expectation of sensational reports from the occupants of
arriving ships. The unusual constru