Pompeii

the mixture, the stronger it set – and then he helped the slaves carry it down in baskets into the matrix and spread it out to form a new base for the conduit. He helped Brebix smash up the rubble they had dug out earlier and they added a couple of layers of that into the base, for strength. He helped saw the planks they used to shutter the walls and to crawl along over the wet cement. He passed bricks to Musa as he laid them. Finally he stood shoulder-to-shoulder with Corvinus to apply the thin coat of render. (And here was the second secret of perfect cement: to pound it as hard as possible, 'hew it as you would hew wood', to squeeze out every last bubble of water or air which might later be a source of weakness.)
    By the time the sky above the manhole was turning grey he knew that they had probably done enough to bring the Augusta back into service. He would have to return to repair her properly. But for now, with a bit of luck, she would hold. He walked with his torch to the end of the patched-up section, inspecting every foot. The waterproof render would be setting even as the aqueduct started to flow again. By the end of the first day it would be hard; by the end of the third it would be stronger than rock.
    If being stronger than rock means anything any more. But he kept the thought to himself.
    'Cement that dries underwater,' he said to Musa when he came back. 'Now that is a miracle.'
    He let the others climb up ahead of him. The breaking day showed that they had pitched their camp in rough pasture, littered with large stones, flanked by mountains. To the east were the steep cliffs of the Appenninus, with a town – Nola, presumably – just becoming visible in the dawn light about five or six miles away. But the shock was to discover how close they were to Vesuvius. It lay directly to the west and the land started to rise almost immediately, within a few hundred paces of the aqueduct, steepening to a point so high the engineer had to tilt his head back to see the summit. And what was most unsettling, now that the shadows were lifting, were the streaks of greyish-white beginning to appear across one of its flanks. They stood out clearly against the surrounding forest, shaped like arrow-heads, pointing towards the summit. If it had not been August he would have sworn that they were made of snow. The others had noticed them as well.
    'Ice?' said Brebix, gawping at the mountain. 'Ice in August?'
    'Did you ever see such a thing, aquarius?' asked Musa.
    Attilius shook his head. He was thinking of the description in the Greek papyri: 'the ash thrown up by Etna's flames makes the land particularly good for vines'.
    'Could it,' he said hesitantly, almost to himself, 'could it perhaps be ash ?'
    'But how can there be ash without fire?' objected Musa. 'And if there had been a fire that size in the darkness we would have seen it.'
    'That's true.' Attilius glanced around at their exhausted, fearful faces. The evidence of their work was everywhere – heaps of rubble, empty amphorae, dead torches, scorched patches where the night's fires had been allowed to burn themselves out. The lake had gone, and with it, he noticed, the birds. He had not heard them leave. Along the mountain ridge opposite Vesuvius the sun was beginning to appear. There was a strange stillness in the air. No birdsong of any sort, he realised. No dawn chorus. That would send the augurs into a frenzy. 'And you're sure it was not there yesterday, when you arrived with Corax?'
    'Yes.' Musa was staring at Vesuvius transfixed. He wiped his hands uneasily on his filthy tunic. 'It must have happened last night. That crash which shook the ground, remember? That must have been it. The mountain has cracked and spewed.'
    There was a general muttering of uneasiness among the men and someone cried out, 'That can only be the giants!'
    Attilius wiped the sweat from his eyes. It was starting to feel hot already. Another scorching day in prospect. And something more than heat – a tautness, like a drumskin stretched too far. Was it his mind playing tricks, or did the ground seem to be vibrating slightly? A prickle of fear stirred the hair on the back of his scalp. Etna and Vesuvius – he was beginning to sense the same terrible connection that Exomnius must have recognised.
    'All right,' he said briskly. 'Let's get away from this place.' He set off towards Corelia. 'Bring everything up out of the matrix,' he called over his shoulder. 'And look sharp about it. We've