in loomed gigantic before them.
Arcot reversed the power and brought the ship to a stop. With the
powerful searchlight, he swept the area, looking for the tower he knew
should be here. At last, he made it out, a pyramid rather than a tower,
and coated over with ice. They soon thawed out the frozen gasses by
playing the energy of three powerful searchlights upon them, and in a
few minutes the glint of gold showed through the melting ice and show.

"It looks," said Wade, "as though they have an outer wall of gold over a
strong wall of iron or steel to protect it from corrosion. Certainly
gold doesn't have enough tensile strength to hold itself up under this
gravity--not in such masses as that."

Arcot brought the ship down beside the tower and the men once more went
out through the airlock into the cold of the almost airless world. They
flew across to the pyramid and looked for some means of entrance. In
several places, they noticed hieroglyphics carved in great, foot-high
characters. They searched in vain for a door until they noticed that the
pyramid was not perfect, but truncated, leaving a flat area on top. The
only joint in the walls seemed to be there, but there was no handle or
visible methods of opening the door.

Arcot turned his powerful light on the surface and searched carefully
for some opening device. He found a bas-relief engraving of a hand
pointing to a corner of the door. He looked more closely and found a
small jewel-like lens set in the metal.

Suddenly the men felt a vibration! There was a heavy click, and the door
panel began to drop slowly.

"Get on it!" Arcot cried. "We can always break our way out if we're
trapped!"

The four men leaped on it and sank slowly with it. The massive walls of
the tower were nearly five feet thick, and made of some tough, white
metal.

"Pure iron!" diagnosed Wade. "Or perhaps a silicon-iron alloy. Not as
strong as steel, but very resistant to corrosion."

When the elevator stopped, they found themselves in a great chamber that
was obviously a museum of the lost race. All around the walls were
arranged models, books, and diagrams.

"We can never hope to take all this in our ship!" said Arcot, looking at
the great collection. "Look--there's an old winged airplane! And a steam
engine--and that's an electric motor! And that thing looks like some
kind of an electric battery."

"But we can't take all that stuff," objected Fuller.

"No," Morey agreed. "I think ou