Above Vesuvius
The Engine screamed high into the air, shedding a contrail of white behind it, letting the power of the thick crystalline spheres in its heart find full release. It was not enough. Below it, below the layer of cloud and haze, the mountain- at last released from ancient constraint- gaped wide and let fury spew.
The top quarter of the cone ripped away in one all-encompassing titanic blast of superheated compressed gas. A mile of corroded lava and soil vaporized in an instant and the sky lit up with a conflagration like the heart of the sun unfolding on earth. Pumice and ash and boulders bigger than the Flavian were ejected into the air, shrieking upward like comets. A shockwave of sound thundered across the land, shattering windows, knocking down trees. It was the forefront of an incandescent cloud of burning gas that swept down the side of the mountain.
The Engine, feeling the power hurtling toward it, banked sharply and screeched off to the north in a steep dive. Air whipped past, over surfaces poorly designed for such velocities. Iron scales tore loose from the skin and sailed away in the slipstream. The great iron wings groaned in torment and in its heart, the pressure of such speed caused the crystal spheres to ring and crack. Tiny fissures rippled over the surface of the globes, spalling flakes of microthin glass into the air. Still, the Engine hurtled on, speeding away in front of the wall of fire.
Seconds after the roof of the mountain had torn away, the deserted villa at Ottaviano was smashed flat by the near-solid wave of air that pressed before the gas cloud. Then the fire swept across it and the trees and fences were consumed. The incandescent gas cloud boiled downslope, consuming everything in its path.
On the seaward side of the mountain, the rupture tore a vast chasm in the side of the cone and the molten heart surged forth, spilling down cliffs and over pastures in a swiftly flowing river. Within minutes, the first vomit of fire had separated into dozens of rivers that rolled inexorably down toward the shore.
At the back of the Engine, in the cargo hold, Thyatis clung for dear life to a metal spar. The wooden crates had crashed forward with the steep dive, tearing loose from their moorings. After climbing into the hold, she had crawled into a space along the wall where she would hide. Now she braced one leg, bleeding from a long slashing cut, against the forward support and put her back to another. Air roared around her, but she was close to blacking out as a vacuum formed in the hold.
The front of the incandescent cloud smashed over the Engine and it lost all flight control. It spun like a leaf in a tornado, cartwheeling through the sky. One wing, stressed beyond even the powerful incantations of the Persian magi, tore from its moorings and vanished into the night. Only the wavering, simmering ward that the Prince had summoned allowed the body of the machine to survive.
In the forward control space, his face smeared again with blood from an exploding glass plate, Maxian clung to a metal support, his fingers white on the iron. Everything tumbled around him, flying up into the air, as the Engine plummeted toward the earth. Outside the oval windows at the front of the Engine, the sky was a blanket of flame. The Prince struggled to maintain the sphere of defense, drawing on the reservoir of power that still spewed from the mountain.
The initial shockwave of superheated air rushed past them, leaving the Engine spinning out of the sky. Maxian dragged himself to the window, his thought stiffening the machine, willing it to restore control. Like a snake, it writhed sideways but suddenly leveled off and hurtled through the air.
Thyatis collapsed back against the spar in stunned relief. With the drop in speed, air circulated in the hold once more and she could breathe. She turned in her little sanctuary, seeing crates slide past her. The rear cargo door, half-twisted by the shock of the wing tearing free, hung open. Scrolls and papers fluttered out of broken crates, snatched by a vicious wind that howled and tore at the chamber. Out there, in the open air, she could see that the world was on fire. But they were low, very low. Burning trees and then a ruined two-story house flashed past.
She swung out of her hiding place, any thought of pain or broken bones banished by the sight of that ragged rectangle and the earth below. Wincing at another tear in her flesh, she pushed the ruined door aside. The wind lashed at her, tearing at her hair. The Engine was still streaking across the flat plain north of the mountain at tremendous speed. Grunting, she put her shoulder against the cargo door and felt it give. There was a giddy sensation of standing at the edge of a vast chasm. She did not look down.
"Stop!" A man's voice, hoarse and ruined by the scalding air, rang out behind her. Thyatis turned and saw the Prince, standing in the doorway from the front of the machine. He was haggard, his dark gray cloak in shreds, his face matted with blood. Curlicues of pale blueand-gold flame flickered around him in an oblate spheroid. When he moved, reaching toward her, it moved like a shadow with him. "You mustn't! The height!"
Thyatis, her face a grim mask, holding only hate in her eyes, pushed away. She fell. Air whipped past and the last thing that she saw was the agonized face of the boy-prince silhouetted in the shattered door of the Engine.
"Fool of a girl!" Maxian reached the cargo door too late. She was gone, sucked away by the whistling blast of wind that roared outside the Engine. "A certain death:."
He turned away. Such reckless abandon had a certain reward. The Engine trembled, fighting through the air. The missing wing crippled it, but Maxian felt such strength at his command that he could will it to fly regardless. He commanded that it soar and seek the cool heavens beyond this inferno. Maxian halted by the big crate, which had jammed itself into the other passageway door. Krista's body, shrunken in death and scored with fire, was still strapped to it. He leaned close and pressed his lips to the charred forehead. Tears fell, sparkling on the ashy flesh.
Then he returned to the command chamber and slumped into the chair that sat there, bolted to the floor. Krista had found it in a shop on the Porticus Aemilla, a heavy block of mahogany carved with ram's head arms and a curved back and covered with soft leather held down by brass nails. The Walach boys had worked for a week to fit it into the control room and get it secured to the decking.
"Rise," he whispered, and the Engine obeyed, soaring into the cold night sky.
Below, a thick choking fog boiled into the air in the wake of the wall of fire. Poison gases curdled and seeped across the land, choking those few animals and men who had survived the first blows. A rain of ash fell as well, settling out of the sky like an ebon blanket. Great stones, flung from the furnace of the mountain, smashed down, sending gouts of water up from the bay at Neapolis. Inland, they crashed into buildings and shattered temples. The coastal towns of Herculaneum and Baiae were first flattened by the blast of burning air, then buried by a thick fall of hot ash and massive stones. Thousands perished trying to flee the conflagration.
The rivers of molten stone continued to rush down the mountainside, burying everything they crossed in a tide of red-hot magma. On the southern side of the mountain, where a gentle slope swept down to the city of Pompeii, there was nothing to arrest the flow. The burning tide rushed on, consuming buildings, barns, fieldstone walls, temples, even the three-tiered bridge on the road to Herculaneum.