h an invasion in view, their scientists had mastered the
language of the country. This had been accomplished very easily, since
in addition to their power of mingling with the populace in an
invisible form, they had the principles of radio developed to a high
degree and were able to tune in on any station they wanted.

Kendrick sat there, stunned, as Cor followed his astounding revelation
of their origin with this calm plan for the conquest of America, of
the world. Why, of all people on earth, had he alone been singled out
for this disclosure?

He asked the question now.

"My dear Professor, can't you really guess?" replied Cor, with that
leathery smile. "Hasn't it dawned that you were a little too near our
own field with that machine of yours? A trifle more research, a
slightly different application--and you would have become a dangerous
enemy."

"You--you mean--?"

"I mean there isn't a great deal of difference between the experiments
you have been making and those our great Ravv once made. For instance,
had you broadcast your heatricity, as you call it, instead of trying
to transmit it on wires--well, picture a receiving apparatus in each
home of the land, like your commercial radio sets. You would have
become a billionaire, don't you see?"

* * * * *

Kendrick saw indeed. It was simple, so simple! Fool--why hadn't he
thought of it?

"But your invention will never make you wealthy now, my dear fellow,"
Cor went on, tauntingly. "You will be our guest, here, until we have
taken over your interesting country. After that, if there is any need
for the broadcasting of heat, we will furnish it ourselves. We have
those facilities, among others, fully developed. Would you care to see
our plant?"

Kendrick naturally admitted that he would, so the dwarf led him
through a rear door and up a winding flight of stairs. They emerged
presently into a great laboratory housed in the glass-roofed pinnacle
of the tower.

There he beheld a sight that left him breathless. Never before had he
seen such an assemblage of scientific apparatus. Its vastness and
strangeness were fairly overpowering, even to a man as well versed in
physio-chemical paraphernalia as he was.

Before his eyes could take in a tenth part of the spectacle, Cor had
led him to the left wall.

"There," he said, "you will observe a development of your heat
generator."

Kendrick looked--to see a long bank of large vacuum-tub