Arnold then ran the _Ithuriel_ up to within a mile of Muswell Hill, and found the remaining thirteen war-balloons in the act of making off to the northward. "Two more time-shells, quick!" he cried. "They are off to take part in the battle to the north, and must be stopped at once. Look lively, or they'll see us and rise out of range!" Almost before the words were out of his mouth one of the guns was ready. A moment later the messenger of destruction was speeding on its way, and they saw it explode fairly in the midst of the squadron. The second followed before the glare of the first explosion had passed, and this was the last shot fired in the aërial warfare between the air-ships and the war-balloons. [Illustration: "The rain of fire spread out far and wide." _See page 344._] The effects of these two shots were most extraordinary. The accurately-timed shells burst, not over, but amidst the aerostats, enveloping their cars in a momentary mist of fire. The intense heat evolved must have suffocated their crews instantaneously. Even if it had not done so their fate would have been scarcely less sudden or terrible, for the fire falling in the cars exploded their own shells even before it burst their gas-envelopes. With a roar and a shock as though heaven and earth were coming together, a vast dazzling mass of flame blazed out, darkening the daylight by contrast, and when it vanished again there was not a fragment of the thirteen aerostats to be seen. "So ends the Tsar's brief empire of the air!" said Arnold, as the smoke of the explosion drifted away. "And twenty-four hours more should see the end of his earthly Empire as well." "I hope so," said Natasha's voice at his elbow. "This awful destruction is sickening me. I knew war was horrible, but this is more like the work of fiends than of men. There is something monstrous, something superhumanly impious, in blasting your fellow-creatures with irresistible lightnings like this, as though you were a god instead of a man. Will you not be glad when it is over, Richard?" "Glad beyond all expression," replied her lover, the angry light of battle instantly dying out of his eyes as he looked upon her sweetly pitiful face. "But tell me, what success has my angel of mercy had in pleading for the lives of her enemies?" he continued, slipping his arm through hers, and leading her aft. "I don't know yet, but my father told me to ask you to go to him as soon as you could leave the deck. Go now, and, Richard, remember what I said to you when you offered me the empire of the world as we were going to Aeria. No one has such influence with the Master as you have, for you have given him the victory and delivered his enemies into his hands. For my sake, and for Humanity's, let your voice be for mercy and peace--surely we have shed blood enough now!" "It shall, angel mine! For your sweet sake I would spare even Alexander Romanoff himself and all his Staff."