long-dead past.

The countless dismal windows, vacant and forlorn, stared, sightless,
from their marble walls; the whole sad city taking on the semblance
of scattered mounds of dead men's sun-bleached skulls--the casements
having the appearance of eyeless sockets, the portals, grinning
jaws.

Closer came the flier, but now its speed was diminishing--yet this
was not Ptarth.

Above the central plaza it stopped, slowly settling Marsward.
Within a hundred yards of the ground it came to rest, floating
gently in the light air, and at the same instant an alarm sounded
at the sleeper's ear.

Carthoris sprang to his feet. Below him he looked to see the
teeming metropolis of Ptarth. Beside him, already, there should
have been an air patrol.

He gazed about in bewildered astonishment. There indeed was a
great city, but it was not Ptarth. No multitudes surged through
its broad avenues. No signs of life broke the dead monotony of
its deserted roof tops. No gorgeous silks, no priceless furs lent
life and colour to the cold marble and the gleaming ersite.

No patrol boat lay ready with its familiar challenge. Silent and
empty lay the great city--empty and silent the surrounding air.

What had happened?

Carthoris examined the dial of his compass. The pointer was set
upon Ptarth. Could the creature of his genius have thus betrayed
him? He would not believe it.

Quickly he unlocked the cover, turning it back upon its hinge. A
single glance showed him the truth, or at least a part of it--the
steel projection that communicated the movement of the pointer upon
the dial to the heart of the mechanism beneath had been severed.

Who could have done the thing--and why?

Carthoris could not hazard even a faint guess. But the thing now
was to learn in what portion of the world he was, and then take up
his interrupted journey once more.

If it had been the purpose of some enemy to delay him, he had
succeeded well, thought Carthoris, as he unlocked the cover of the
second dial the first having shown that its pointer had not been
set at all.

Beneath the second dial he found the steel pin severed as in the
other, but the controlling mechanism had first been set for a point
upon the western hemisphere.

He had just time to judge his location roughly at some place
south-west of Helium, and at a considerable distance from the twin
cities, when he was startled by a woman's scream beneath him.

Leaning over the side of