And this was the problem, in the engineer's opinion. She had to do too much. Rome, after all, had more than half a dozen aqueducts: if one failed the others could make up the deficit. But there was no reserve supply down here, especially not in this drought, now dragging into its third month. Wells that had provided water for generations had turned into tubes of dust. Streams had dried up. Riverbeds had become tracks for farmers to drive their beasts along to market. Even the Augusta was showing signs of exhaustion, the level of her enormous reservoir dropping hourly, and it was this that had brought him out onto the hillside in the time before dawn when he ought to have been in bed.

From the leather pouch on his belt Attilius withdrew a small block of polished cedar with a chin rest carved into one side of it. The grain of the wood had been rubbed smooth and bright by the skin of his ancestors. His great-grandfather was said to have been given it as a talisman by Vitruvius, architect to the Divine Augustus, and the old man had maintained that the spirit of Neptune, god of water, lived within it. Attilius had no time for gods. Boys with wings on their feet, women riding dolphins, greybeards hurling bolts of lightning off the tops of mountains in fits of temper—these were stories for children, not men. He placed his faith instead in stones and water, and in the daily miracle that came from mixing two parts of slaked lime to five parts of puteolanum—the local red sand— conjuring up a substance that would set underwater with a consistency harder than rock.

But still—it was a fool who denied the existence of luck, and if this family heirloom could bring him that . . . He ran his finger around its edge. He would try anything once.

He had left his rolls of Vitruvius behind in Rome. Not that it mattered. They had been hammered into him since childhood, as other boys learned their Virgil. He could still recite entire passages by heart.

"These are the growing things to be found which are signs of water: slender rushes, wild willow, alder, chaste berry, ivy, and other things of this sort, which cannot occur on their own without moisture . . ."

"Corax over there," ordered Attilius. "Corvinus there. Becco, take the pole and mark the place I tell you. You two: keep your eyes open."

Corax gave him a look as he passed.

"Later," said Attilius. The overseer stank of resentment almost as strongly as he reeked of wine, but there would be time enough to settle their quarrel when they got back to Misenum. For now they would have to hurry.

A gray gauze had filtered out the stars. The moon had dipped. Fifteen miles to the east, at the midpoint of the bay, the forested pyramid of Mount Vesuvius was becoming visible. The sun would rise behind it.

"This is how to test for water: lie face down, before sunrise, in the places where the search is to be made, and with your chin set on the ground and propped, survey these regions. In this way the line of sight will not wander higher than it should, because the chin will be motionless . . ."

Excerpted from Pompeii by Robert Harris. Copyright © 2003 by Robert Harris. Excerpted by permission of Random House, a division of Random House, Inc. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.