wift words of
instruction, she stood up on tiptoe, put her arms about my neck, and
kissed me full on the lips.

Miela laughed gayly.

"You must love her very much, Alan. And she--your little sister--will love
you, too. She is very sweet."

Then her face sobered suddenly.

"Tao has returned, Alan. And he has sent messengers to our city. They are
appealing to our people to join Tao in his great conquest. They say Tao
has here with him, on Mercury, a captive earthman, with wonderful strength
of body, who will help in the destruction of his own world!"

CHAPTER XIII.

THE CAPTIVE EARTH-MAN.

As we came out of the valley I had my first view of the Great City. It
occupied a huge, mound-shaped circular mountain which rose alone out of
the wide plain that spread before me. As far as I could see extended a
rich muddy soil partially covered with water. A road led out of the
valley, stretching across these wet fields toward the base of the
mountain. It was built on an embankment some eight or ten feet high, of
the red, metallic ore of the mountains.

All along the base of this embankment, with their roots in the water,
graceful trees like palms curved upward over the road. The landscape was
dotted with these and other tropical trees; the scene was, indeed,
essentially tropical.

I wondered at the continued absence of sight of human beings. The fields
were quite evidently under cultivation. A rise of ground off to the left
was ridged with terraces. As we passed on along the road I saw a rude form
of plow standing where it had been left in a field which evidently was
producing rice or something akin to it. Yet there was not a person in
sight. Only ahead in the sky I could see a little cluster of black dots
that Miela said was a group of females hovering about the summit of the
Great City.

"It is the time of sleep now, Alan," she said, in answer to my question.

I had not thought of that. It was broad daylight, but here on Mercury
there was no day or night, but always the same half light, as of a cloudy
day.

The mountain on which the city was built was dotted thickly with palms,
and as we approached I made out the houses of the city, set amid the
trees, with broad streets converging at the top. As we came still closer I
saw that the summit of the mountain was laid out like some beautiful
tropical garden, with a broad, low-lying palace in its center.

When we were still a mile or so away from the outskirts o