r place had been run out the
smaller but more powerful water propellers. As these commenced to
revolve the ship took up its journey once more, riding the new element
as buoyantly and as safely as she had the air.

Phaidor and I were dumbfounded. Neither had either heard or dreamed
that such a world existed beneath the surface of Barsoom.

Nearly all the vessels we saw were war craft. There were a few
lighters and barges, but none of the great merchantmen such as ply the
upper air between the cities of the outer world.

"Here is the harbour of the navy of the First Born," said a voice
behind us, and turning we saw Xodar watching us with an amused smile on
his lips.

"This sea," he continued, "is larger than Korus. It receives the
waters of the lesser sea above it. To keep it from filling above a
certain level we have four great pumping stations that force the
oversupply back into the reservoirs far north from which the red men
draw the water which irrigates their farm lands."

A new light burst on me with this explanation. The red men had always
considered it a miracle that caused great columns of water to spurt
from the solid rock of their reservoir sides to increase the supply of
the precious liquid which is so scarce in the outer world of Mars.

Never had their learned men been able to fathom the secret of the
source of this enormous volume of water. As ages passed they had
simply come to accept it as a matter of course and ceased to question
its origin.

We passed several islands on which were strangely shaped circular
buildings, apparently roofless, and pierced midway between the ground
and their tops with small, heavily barred windows. They bore the
earmarks of prisons, which were further accentuated by the armed guards
who squatted on low benches without, or patrolled the short beach lines.

Few of these islets contained over an acre of ground, but presently we
sighted a much larger one directly ahead. This proved to be our
destination, and the great ship was soon made fast against the steep
shore.

Xodar signalled us to follow him and with a half-dozen officers and men
we left the battleship and approached a large oval structure a couple
of hundred yards from the shore.

"You shall soon see Issus," said Xodar to Phaidor. "The few prisoners
we take are presented to her. Occasionally she selects slaves from
among them to replenish the ranks of her handmaidens. None serves
Issus above a sing