Pompeii

sections of tree-trunk, a foot thick. Their rumble could be heard a mile away. First the oxen passed him, heads down, each team led by a man with a stick, and then the lumbering carts, and finally the rest of the work gang. He counted them. They were all there, including Brebix. Beside the road, the marker-stones of the aqueduct, one every hundred paces, dwindled into the distance. Neatly spaced between them were the round stone inspection covers that provided access to the tunnel. The regularity and precision of it gave the engineer a fleeting sense of confidence. If nothing else, he knew how this worked.
    He spurred his horse.
    An hour later, with the afternoon sun dipping towards the bay, they were halfway across the plain – the parched and narrow fields and bone-dry ditches spread out all around them, the ochre-coloured walls and watchtowers of Pompeii dissolving into the dust at their backs, the line of the aqueduct leading them remorselessly onwards, towards the blue-grey pyramid of Vesuvius, looming ever more massively ahead.

Hora duodecima

    [18:47 hours]

'While rocks are extremely strong in compression, they are weak in tension (strengths of about 1.5 × 10 7 bars). Thus, the strength of the rocks capping a cooling and vesiculating magma body is easily exceeded long before the magma is solid. Once this happens, an explosive eruption occurs.'
Volcanoes: A Planetary Perspective

    Pliny had been monitoring the frequency of the trembling throughout the day – or, more accurately, his secretary, Alexion, had been doing it for him, seated at the table in the admiral's library, with the water clock on one side and the wine bowl on the other.
    The fact that it was a public holiday had made no difference to the admiral's routine. He worked whatever day it was. He had broken off from his reading and dictation only once, in the middle of the morning, to bid goodbye to his guests, and had insisted on accompanying them down to the harbour to see them aboard their boats. Lucius Pomponianus and Livia were bound for Stabiae, on the far side of the bay, and it had been arranged that they would take Rectina with them in their modest cruiser, as far as the Villa Calpurnia in Herculaneum. Pedius Cascus, without his wife, would take his own fully manned liburnian to Rome for a council meeting with the Emperor. Old, dear friends! He had embraced them warmly. Pomponianus could play the fool, it was true, but his father, the great Pomponianus Secundus, had been Pliny's patron, and he felt a debt of honour to the family. And as for Pedius and Rectina – their generosity to him had been without limit. It would have been hard for him to finish the Natural History, living outside Rome, without the use of their library.
    Just before he boarded his ship, Pedius had taken him by the arm. 'I didn't like to mention it earlier, Pliny, but are you sure you're quite well?'
    'Too fat,' wheezed Pliny, 'that's all.'
    'What do your doctors say?'
    'Doctors? I won't let those Greek tricksters anywhere near me. Only doctors can murder a man with impunity.'
    'But look at you, man – your heart –'
    '"In cardiac disease the one hope of relief lies undoubtedly in wine." You should read my book. And that, my dear Pedius, is a medicine I can administer myself.'
    The senator looked at him, then said grimly, 'The Emperor is concerned about you.'
    That gave Pliny a twinge in his heart, right enough. He was a member of the imperial council himself. Why had he not been invited to this meeting, to which Pedius was hurrying? 'What are you implying? That he thinks I'm past it?'
    Pedius said nothing – a nothing that said everything. He suddenly opened his arms and Pliny leaned forwards and hugged him, patting the senator's stiff back with his pudgy hand. 'Take care, old friend.'
    'And you.'
    To his shame, when Pliny pulled back from the embrace, his cheek was wet. He stayed on the quayside, watching until the ships were out of sight. That was all he seemed to do these days: watch other people leave.
    The conversation with Pedius had stayed with him all day, as he shuffled back and forth on the terrace, periodically wandering into the library to check Alexion's neat columns of figures. 'The Emperor is concerned about you.' Like the pain in his side, it would not go away.
    He took refuge, as always, in his observations. The number of harmonic episodes, as he had decided to call the tremors, had increased steadily. Five in the first hour, seven in the