our tiny power pipes of
silver."

"This man is Stel Felso Theu," said Tho Stan Drel. "The greatest of our
scientists, the man who has invented this weapon which alone seems to
offer us hope. And I am afraid he is right. See, there is the
University. For the power requirements of their laboratories, a heavy
power line has been installed, and it was hoped that you could carry
leads into it." His face showed evident despair greater than ever.

"We can always feed some power into the lines. Let us see just what hope
there is. I think that it would be wiser to investigate the power lines
at once," suggested Morey.

Ten minutes later, with but a single officer now accompanying them, Tho
Stan Drel, the terrestrial scientist, and the Talsonian scientist were
inspecting the power installation.

They had entered a large stone building, into which led numerous very
heavy silver wires. The insulators were silicate glass. Their height
suggested a voltage of well over one hundred thousand, and such heavy
cables suggested a very heavy amperage, so that a tremendous load was
expected.

Within the building were a series of gigantic glass tubes, their walls
fully three inches thick, and even so, braced with heavy platinum rods.
Inside the tubes were tremendous elements such as the tiny tubes of
their machine carried. Great cables led into them, and now their heating
coils were glowing a somberly deep red.

Along the walls were the switchboards, dozens of them, all sizes, all
types of instruments, strange to the eyes of the terrestrians, and in
practically all the light-beam indicator system was used, no metallic
pointers, but tiny mirrors directing a very fine line of brilliant light
acted as a needle. The system thus had practically no inertia.

"Are these the changers?" asked Arcot gazing at the gigantic tubes.

"They are; each tube will handle up to a hundred thousand volts," said
Stel Felso Theu.

"But I fear, Stel Felso Theu, that these tubes will carry power only one
way; that is, it would be impossible for power to be pumped from here
into the power house, though the process can be reversed," pointed out
Arcot. "Radio tubes work only one way, which is why they can act as
rectifiers. The same was true of these tubes. They could carry power one
way only."

"True, of tubes in general," replied the Talsonian, "and I see by that
that you know the entire theory of our tubes, which is rather abstruse."

"We use them on the