as waves of _heatricity_, to use the
word he had coined.

Those were Kendrick's theories, and now he moved to put them to the
supreme test. Switching on the current, he set the motor going. In
response, the cross began to revolve, slowly at first--then faster,
faster, as he opened the rheostat wider.

Eyes fixed on his resistance coils, he gave a sudden cry of triumph.
Yes, there was no doubt about it! They were growing red, glowing
brightly, whitely, above the intense desert sunlight.

Here was a means of convening solar radiation into heat, then, that
offered tremendous commercial possibilities!

But even as he exulted, there came a blinding flash--and the overtaxed
coils burst into flame.

* * * * *

Shielding his eyes from the glare, he reached for the rheostat, shut
off the current, rushed to his secondary unit--where he beheld an
amazing sight. Not only had this part of the apparatus completely
disintegrated, but the sand of the desert floor under it as well. On
the spot quivered a miniature lake of molten glass!

As Kendrick stood ruefully beside that fiery pool, meditating on the
spectacular but not altogether gratifying results of his experiment, a
peculiar low humming sound reached his ears. Rushing back to his
primary unit, with the thought that perhaps by some chance he had not
fully closed the rheostat, he looked at the cross. But no, the vanes
were still.

The humming increased, however--grew into a vibration that made his
eardrums ache.

Puzzled, he looked around. What on earth could it be? Had his unruly
experiment called into play some tremendous, unsuspected force of the
universe. Was he to bring the world to ruin, as a result of his blind
groping after this new giant of power?

Such predictions had often been made by the ignorant, to be dismissed
by scientists as the veriest nonsense. But was there some truth in the
universal fear, after all? Was he to be the Prometheus who stole fire
from Olympus, the Samson who toppled down the temple?

Chilled, dizzied with the pain of the ever-increasing vibration, he
gritted his teeth, awaiting he knew not what.

Then it came--a spectacle so staggering that he went rigid with awe as
he regarded it, all power of motion utterly numbed for the moment. The
vibration ceased. The thing appeared.

It was a city--a city in the air--a flying city!

* * * * *

As Kendrick stood staring at thi