is dolphin-shaped horn and
blew three short blasts while Nelson, in sudden alarm, cocked his
rifle and brought it in line with the other's chest. The glittering
officer saw the motion, but made no effort to move from the line of
sights.

"Thy gesture avails naught," said he with stiff courtesy. "When Hero
Giles gives his word, it stands good though Heliopolis and the Empire
of the Atlans fall."

One by one half a dozen spearmen appeared, all obviously very
frightened and only moved by an apparently Spartan discipline.
Promptly they saluted, whereupon the Hero--as his title appeared to
be--uttered a number of brief commands in some guttural language
entirely unintelligible to the dazed aviator.

* * * * *

Presently a strange column appeared, composed of some fifteen or
twenty disarmed men marching between a double rank of heavily equipped
hoplites. As they drew near, they clasped imploring hands and
evidently begged for mercy from the stern, tight jawed figure at
Nelson's side. Contemptuous and unhearing the prisoners' piteous
pleadings and lamentations, Hero Giles scowled upon them and
deliberately turned his back.

"What are they?" inquired Nelson, vaguely alarmed. "Enemies?"

"Yes." There was a certain bitter savagery in the speaker's voice.
"These are the dauntless defenders of Atlans who ran at the report of
thy weapon. Presently they die."

It was useless to interfere. The horrified aviator knew it and watched
with compassionate eyes while the condemned soldiers were ranged in a
single, white faced line. They remained silent now, seeming to have
found courage now that hope was dead.

Upon brief command from a subaltern, the guards wheeled about and
retreated perhaps twenty yards down the passage. There they halted,
glittering eyes peering through the slots in their helmets to fix
themselves upon the rigid prisoners who stood numbly resigned to
death.

With surprising speed each member of that weird firing squad detached
a brazen grenade from his belt, then threw back his arm in exactly the
same attitude as a bomb-throwing doughboy. Then there came a short,
sharp command and some fifteen or twenty grenades bobbed through the
air to crash on the stones at the feet of the victims.

* * * * *

His head swimming with repulsion at the slaughter, Nelson beheld a
curious sight. It seemed that from the broken grenades appeared a
yellowish green v