was sure that eyes watched them from somewhere behind that
blank wall.

He glanced at Thuvia. She was advancing with wide eyes fixed upon
the city gate. He looked in the direction of her gaze, but saw
nothing.

His gaze upon her seemed to arouse her as from a lethargy. She
glanced up at him, a quick, brave smile touching her lips, and then,
as though the act was involuntary, she came close to his side and
placed one of her hands in his.

He guessed that something within her that was beyond her conscious
control was appealing to him for protection. He threw an arm about
her, and thus they crossed the field. She did not draw away from
him. It is doubtful that she realized that his arm was there, so
engrossed was she in the mystery of the strange city before them.

They stopped before the gate. It was a mighty thing. From its
construction Carthoris could but dimly speculate upon its unthinkable
antiquity.

It was circular, closing a circular aperture, and the Heliumite knew
from his study of ancient Barsoomian architecture that it rolled
to one side, like a huge wheel, into an aperture in the wall.

Even such world-old cities as ancient Aaanthor were as yet undreamed
of when the races lived that built such gates as these.

As he stood speculating upon the identity of this forgotten city,
a voice spoke to them from above. Both looked up. There, leaning
over the edge of the high wall, was a man.

His hair was auburn, his skin fair--fairer even than that of John
Carter, the Virginian. His forehead was high, his eyes large and
intelligent.

The language that he used was intelligible to the two below,
yet there was a marked difference between it and their Barsoomian
tongue.

"Who are you?" he asked. "And what do you here before the gate of
Lothar?"

"We are friends," replied Carthoris. "This be the princess,
Thuvia of Ptarth, who was captured by the Torquasian horde. I am
Carthoris of Helium, Prince of the house of Tardos Mors, Jeddak of
Helium, and son of John Carter, Warlord of Mars, and of his wife,
Dejah Thoris."

"'Ptarth'?" repeated the man. "'Helium'?" He shook his head. "I
never have heard of these places, nor did I know that there dwelt
upon Barsoom a race of thy strange colour. Where may these cities
lie, of which you speak? From our loftiest tower we have never
seen another city than Lothar."

Carthoris pointed toward the north-east.

"In that direction lie Helium and Ptarth,"