Pompeii

older than his forty years. He had a wife and a brood of children crammed into an apartment across the street from the reservoir. Attilius wondered why Corax hated him so much. Was it simply that he had coveted the post of aquarius for himself and resented the arrival of a younger man from Rome? Or was there something more?
    He told Corax to row them towards the centre of the Piscina and when they reached it he handed him the torch, uncorked the bottle and rolled up the sleeves of his tunic. How often had he seen his father do this, in the subterranean reservoir of the Claudia and the Anio Novus on the Esquiline Hill? The old man had shown him how each of the matrices had its own flavour, as distinct from another as different vintages of wine. The Aqua Marcia was the sweetest-tasting, drawn from the three clear springs of the River Anio; the Aqua Alsietina the foulest, a gritty lakewater, fit only for irrigating gardens; the Aqua Julia, soft and tepid; and so on. A good aquarius, his father had said, should know more than just the solid laws of architecture and hydraulics – he should have a taste, a nose, a feel for water, and for the rocks and soils through which it had passed on its journey to the surface. Lives might depend on this skill.
    An image of his father flashed into his mind. Killed before he was fifty by the lead he had worked with all his life, leaving Attilius, a teenager, as head of the family. There had not been much left of him by the end. Just a thin shroud of white skin stretched taut over sharp bone.
    His father would have known what to do.
    Holding the bottle so that its top was face down to the water, Attilius stretched over the side and plunged it in as far as he could, then slowly turned it underwater, letting the air escape in a stream of bubbles. He recorked it and withdrew it.
    Settled back in the boat, he opened the bottle again and passed it back and forth beneath his nose. He took a mouthful, gargled and swallowed. Bitter, but drinkable, just about. He passed it to Corax who swapped it for the torch and gulped the whole lot down in one go. He wiped his mouth with the back of his hand. 'It'll do,' he said, 'if you mix it with enough wine.'
    The boat bumped against a pillar and Attilius noticed the widening line between the dry and damp concrete – sharply defined, already a foot above the surface of the reservoir. She was draining away faster than the Augusta could fill her.
    Panic again. Fight it.
    'What's the capacity of the Piscina?'
    'Two hundred and eighty quinariae.'
    Attilius raised the torch towards the roof, which disappeared into the shadows about fifteen feet above them. So that meant the water was perhaps thirty-five feet deep, the reservoir two-thirds full. Suppose it now held two hundred quinariae. At Rome, they worked on the basis that one quinaria was roughly the daily requirement of two hundred people. The naval garrison at Misenum was ten thousand strong, plus, say, another ten thousand civilians.
    A simple enough calculation.
    They had water for two days. Assuming they could ration the flow to perhaps an hour at dawn and another at dusk. And assuming the concentration of sulphur at the bottom of the Piscina was as weak as it was at the top. He tried to think. Sulphur in a natural spring was warm, and therefore rose to the surface. But sulphur when it had cooled to the same temperature as the surrounding water – what did that do? Did it disperse? Or float? Or sink?
    Attilius glanced towards the northern end of the reservoir, where the Augusta emerged. 'We should check the pressure.'
    Corax began to row with powerful strokes, steering them expertly around the labyrinth of pillars towards the falling water. Attilius held the torch in one hand and with the other he unrolled the plans, flattening them out across his knees with his forearm.
    The whole of the western end of the bay, from Neapolis to Cumae, was sulphurous – he knew that much. Green translucent lumps of sulphur were dug from the mines in the Leucogaei Hills, two miles north of the aqueduct's main line. Then there were the hot sulphur springs around Baiae, to which convalescents came from across the Empire. There was a pool called Posidian, named after a freedman of Claudius, that was hot enough to cook meat. Even the sea at Baiae occasionally steamed with sulphur, the sick wallowing in its shallows in the hope of relief. It must be somewhere in this smouldering region – where the Sibyl had her cave and