As we were about to part, I asked, 'Did you know the late Librarian, Theon?'

Aedemon must have heard what had happened. Maybe Zenon had just told him. The big physician looked sorrowful. 'I met Theon many years ago. Now he he was a black bile man. Morose. Irritable. p.r.o.ne to lack of confidence. A sink of putrid matter clogging him.' was a black bile man. Morose. Irritable. p.r.o.ne to lack of confidence. A sink of putrid matter clogging him.'

'Suicidal?'

'Oh, easily!Especially if he had been thwarted.'

Regularly, by Philetus, for instance.

Even without a purge or emetic, I felt inspired as I went up to the roof.

The astronomer, that man of few words, turned away on principle.

'Just one question, Zenon. Please just answer one for me: has Philetus been injecting cash into the Museion's funds?' Please just answer one for me: has Philetus been injecting cash into the Museion's funds?'

'No, Falco.'

'No money has been realised from selling Library scrolls?'

'You had your one question.'

'Aedemon calls you a pillar of morality. Humour me. Don't be pointlessly pedantic. Confirm the supplementary, please.'

'As I said - no. The Director has not boosted our accounts with income from his secret scroll-selling. I've been waiting to receive it - but he keeps the money himself.' The Director has not boosted our accounts with income from his secret scroll-selling. I've been waiting to receive it - but he keeps the money himself.'

'Thank you,' I said sweetly.

Zenon smiled. I took it as encouragement for my enquiries. Aedemon's cure must already be working. Or had the celestial stars and planets foretold to Zenon that the downfall of Philetus might be imminent?

The Director was about to bring doom on himself. Just at that moment we spotted from the observatory roof a column of alarming black smoke. Zenon and I were horrified. The Great Library was on fire.

LIV.

The emergency loosened up my stiff joints and sinews. I made it down the stairs ahead of Zenon, then we raced to the Library in tandem. We pounded into the main hall, but everywhere seemed clear. Readers looked up from their scrolls and glared at us for disturbing them with indecorous behaviour. So far at least, the famous monument was in no danger. We shouted 'Fire!' to alert the a.s.sistants. If the fire spread from its seat - wherever that was - we knew the peaceful atmosphere could change in moments.

We rushed back outside. We could smell the smoke, but not see it. Scooping up the young scholars who always loitered in the portico, we hurried around the main block to the utility area where I had been yesterday. The fire was in the very building where Diogenes' scrolls had been stored, prior to removal. The Khamseen was blowing today, which unsettled us and fanned the flames.

A crowd had gathered, watching dopily. Zenon and I mobilised those who looked handy, instructing the rest to scram. With the helpers we had brought, we did what we could. The scholars responded well. They were young, fit and eager for practical experiments. They used their minds to devise sensible activities. Anything that could beat out flames was fetched quickly; some eager exhibitionists stripped off and used their tunics. Buckets were found - perhaps, like the fire platform at the Pharos, the Library had equipment stored in case of such an emergency. Its cleaners would have buckets too. Our lads soon organised a human chain to manhandle these after filling them at the great ornamental pool in the forecourt.

They did well, but the Library was an enormous construction. Zenon muttered that the marble would not burn. I reckoned he was wrong. Even marble crumbles, if it becomes hot enough; the surface splits off, so flakes the size of dinner platters crash down. Even if we could save the building, this fire might be disastrous for its historic fabric.

By the time buckets reached us, much of the water had sloshed out. The fire had taken hold, unnoticed, before we even started. Thick smoke impeded us. After yesterday, I was half unmanned by the heat, desperately trying to ensure that n.o.body was burned. The hideous spectre of the badly disfigured Diogenes swam in visions before me as I worked.

We were losing the battle. Any moment now, the flames would break through the workshop roof. Once that went up, fire would leap to other nearby buildings, carried over by the wind. Anyone who had seen a city blaze must have been aware we were on the brink of tragedy.

I wished we were in Rome where we could call on the vigiles. Other cities in the Empire had no fire brigades; they were discouraged, since emperors feared allowing remote foreign provinces to run any semi-military organisations. If word reached the Prefect's palace, whatever soldiers were in Alexandria could come and help us, but most of the legionaries would be in their camp, outside the city. Any message would be too late. All we could expect were dregs. I sent a lad who had long legs to run for help anyway. If we were about to lose the Library, the news would rush around the world. Once the recriminations started to fly, official witnesses would be a benefit.

Panic set in. Hopelessness quickly followed. The first bursts of youthful energy had run out. Our efforts were starting to seem pointless. We were tired and dirty, running with sweat and steam. The heat was beginning to drive us back.

Zenon rallied the young men for one last strenuous attempt. I directed them where the flames were worst. The buckets kept coming but what we achieved was pitiful. We were close to exhaustion, barely managing to hold our own. Then, trundling through the glorious porticoes, I made out the dim outline of a large, unsteady cart. Double lines of straining young men towed it on hauling-ropes. As this c.u.mbersome edifice emerged through the smoke and teetered on a corner, I was astonished to see that my own Helena Justina led the way. Seeing me, she cried, 'Marcus! I noticed this in one of the lecture halls. The engineering students were to have a demonstration - this is based on the siphon pump invented by Ctesibius, three hundred years ago, with modern modifications by Heron of Alexandria -'

n.o.body knew how to operate the beast. They had not heard their lecture yet. But my best friend in Rome, Lucius Petronius, worked with the vigiles. So I knew.

Fortunately the water tank was full, in preparation for planned demonstration. This would be better. This was for real.

We put up a couple of the most powerful students, one each end, where they had to work the two great levers of the rocker arm up and down on its central post.

'Go steadily!' I ordered as they creaked into action far too fast. They soon mastered the right pace. The hosepipe turned on a universal joint; it could be adjusted in any direction. Directing the pipe gave no trouble to inquisitive, practical lads who had come to Alexandria hoping to become mad inventors. They all wanted to be the new Archimedes, or at best follow Heron, their mentor. As the rocker arm creaked and brought the two pistons into play, advice from me was unnecessary. They were soon spraying away with the hose nozzle as if they had just come from a vigiles' training exercise in the Fourth Cohort's station yard. So, as the jealous boys on the bucket chain redoubled their efforts to compete in glory, I dared mouth to Zenon, 'We may be winning!'

True to form, he made no answer.

Eventually, the water tank on the siphon engine ran bone dry. But the blaze which had threatened to overwhelm us was now reduced to glowing embers. Buckets tell from numb hands as our helpers collapsed, completely played out. The young men lay on the ground, groaning loudly after their unaccustomed effort. Even those who practised athletics had been severely tested; I could see they were astonished at how depleted they felt. Zenon and I flopped on a stone bench, coughing.

Helena Justina, fetchingly besmirched by s.m.u.ts, sat on a small patch of gra.s.s, clutching her knees. Dreamily she lectured us: 'Ctesibius, the son of a barber, was the first head of the Museion. His inventions included an adjustable shaving mirror, which moved on a counterweight, but he is best known as the father of pneumatics. To him we owe the water organ, or hydraulis, hydraulis, and the most efficient version of the lawyer's water clock, or and the most efficient version of the lawyer's water clock, or clepsydra. clepsydra. His work on force pumps enabled him to produce a jet of water, for use in a fountain or for lifting water from wells. He discovered the principle of the siphon, which we have had demonstrated with such good effect today! However, it may be said that setting fire to the Great Library was a drastic way to ill.u.s.trate pumping principles. This empirical approach may have to be rethought in future.' His work on force pumps enabled him to produce a jet of water, for use in a fountain or for lifting water from wells. He discovered the principle of the siphon, which we have had demonstrated with such good effect today! However, it may be said that setting fire to the Great Library was a drastic way to ill.u.s.trate pumping principles. This empirical approach may have to be rethought in future.'

Her listeners cheered. Some recovered enough to laugh.

'Ctesibius,' Helena added, her voice a.s.suming self-mockery as she ventured into propaganda, 'had the advantage of working for benign pharaohs who supported invention and the arts. Fortunately, you now have a similar advantage, since you live in the reign of Vespasian Augustus, who was of course first brought to power in this wonderful city of Alexandria.'

'The scholars have shown today that they fully appreciate their good fortune,' I croaked. I too could sound priggish.

'Many thanks to all of you for your bravery and hard work,' cried Helena. 'And look! - Now the excitement is all over, here is the wonderful Academic Board coming to congratulate you on saving the Library!'

Through the thinning smoke, we beheld Philetus. He waddled at the head of a small bearded entourage: Apollophanes the philosopher, Timosthenes from the Serapeion, Nicanor the lawyer. On the bench at my side, Zenon growled in the back of his throat. Neither he nor I stood up. We were begrimed with smoke, our eyes red and stinging. Neither of us was in a mood to tolerate a condescending idiot.

Philetus moved among the youthful firefighters, placing a hand approvingly on one, murmuring praise to another. If he had thought to bring garlands, the oily sycophant would have draped their necks or crowned their sooty heads like triumphal Olympians. The scholars knew better than to shy away, but they looked nervous. I had worked out just how hypocritical Philetus was being about this workshop fire.

He ignored Zenon and me. He side-stepped the siphon engine too, as if appreciating mechanics, and the beauty of utility, was beyond him.

He approached the burnt-out workshop. Heat that the ancient stones had absorbed still beat off the pharaonic blocks, so Philetus only ventured as far as the granite threshold. He looked in. 'Oh dear! There seems to be nothing left of the contents.'

I stood up. Behind me, the astronomer stayed put, but he folded his fingers together like an eager member of a popular audience who is about to watch a prize-winning play.

I crossed to Philetus and sounded apprehensive. 'Really! What contents would those be, Director?'

'We were storing a large quant.i.ty of library scrolls in this building, Falco -'

'Oh no! Are you sure?' Are you sure?'

'I had them put here myself. They are all lost!'

'We were able to save nothing from inside, sadly,' I told him, apparently full of regret.

'Then a great many valuable works of culture have been burned to ashes.'

'Are you saying so?' I stiffened up. 'Good try, Philetus!'

'What?' He was about to resort to bl.u.s.ter - too late.

Apollophanes,Timosthenes and Nicanor pulled back from supporting him at the same moment. Those three worthies saw where we were heading. All were up for the post of Librarian - and if Philetus fell, they would be scratching for the directorship as well. Mental repositioning began right there. The candidates were ready for huckstering even before the old Director saw that he was finished.

'Those would be the scrolls,' I spelled out slowly, 'that were taken away from here last night by a trader called Diogenes. Philetus, you sold them to him - wrongfully, secretly and for your own benefit. Not only did you dispose of irreplaceable material that had been collected over centuries, you personally took the money.'

He was about to deny it. I stopped him.

'Don't add to your misdemeanour by publicly lying. Diogenes was taken while in commission of your theft. Now the scrolls are in safe custody. They will be returned to the Library. Dress up what you have done, Philetus, however you like. I call it fraud. I call it theft.'

'You exaggerate!' He was too foolish to recognise that the end had come.

Before I could speak, someone else drawled laconically, 'Sounds good to me!' Hardly believable: that was Apollophanes, the Director's own sneak. He was a worm - but worms, it seemed, could turn.

I strode right up to Philetus and dragged him inside the smouldering store. The charred walls still glowed, as I kicked aside the burnt remains of a table. We could barely breathe in the smoke, but I was so angry I managed to speak. 'What did you say - Oh dear - there seems to be nothing left of the contents ? Oh dear - there seems to be nothing left of the contents ?You hoped not, of course. You wanted them to seem gone, to hide that they were missing.'

I gripped the scared Director by the tunic edge and hauled him towards me on tiptoe. 'Listen to me, Philetus; listen well! I bet you had this building torched. Why don't I arrest you here and now? Only because I can't yet prove that you had this fire set. If I ever do find evidence, you are done for. Arson to a public building is a capital offence.'

He gurgled. I dropped him. 'You disgust me. I cannot even bear to spend my time on an indictment. Men like you are so insidiously evil, you destroy everything; you drive everyone who has to deal with you to inertia and despair. You are not worth my trouble. Besides, I truly believe in this inst.i.tution that you have misgoverned and plundered. The reason for the Museion lies in those young men lying exhausted outside. Today they used their knowledge, their vision, their application. They were courageous and dedicated. They They justify this place of knowledge - its learning, its invention, its devotion to ideas and its development of minds.' justify this place of knowledge - its learning, its invention, its devotion to ideas and its development of minds.'

I shoved him out into the air. 'Send your resignation to the Prefect tonight. It will be accepted. Do it yourself is my advice. Otherwise -' I quoted words of his own back to him:' Occasionally we might suggest a very elderly man has become too frail to continue .' Occasionally we might suggest a very elderly man has become too frail to continue .'

Philetus would go, even if under protest. It would obviate the need for enquiries, recriminations, pet.i.tions to the Emperor, and, above all, scandal. He might yet be given a pension, or keep his right to a statue in the line of former directors, those great men whose impressive administrations had been inst.i.tuted by Ctesibius, the father of pneumatic science. Who knows? Philetus might even keep his reading rights at the Library. I knew life was full of ironies.

I hated this, but I was a realist. I had served my Emperor long enough to know the style of action Vespasian wanted. Resignation would be painless and tidy, limiting awkwardness and adverse public comment. And it would be immediate.

LV.

Alexandria might be the foremost training place for the mind, but it was ruining me physically. I looked for Helena, hoping we could gather ourselves together and go home. 'Home' was beginning to have a Roman resonance, even though we were nowhere near finishing with Egypt.

I was downhearted to see her on her feet, talking avidly to an elderly man. He was a typical Museion greybeard, though older than most and leaning heavily on walking sticks. Though gaunt and probably in pain, he had that look in his eye of a thinker who refused to give up while there was still any chance he might crack one of the world's great puzzles.

'Marcus, come quickly and be introduced - I am so thrilled!' For the cool and refined Helena Justina to gush was unexpected. 'This is Heron, Marcus - Heron of Alexandria! It is such a privilege to meet you, sir - my brother Aelia.n.u.s will be so excited: Marcus, I have invited Heron to dine with us.'

I bet she had not told the great automaton-maker that her brother once spent weeks trailing around the New Rich of remote Britannia, trying to sell those deluded culture-seekers dud versions of Heron's moving statues. One of the statues accidentally killed someone, but we hushed it up with the excuse that the dead man was a bath-house installer. Maybe Heron would enjoy that; he was human, for he pierced me with merry eyes and said, 'If you are Marcus Didius Falco, the investigator everyone talks about, I want a word on a professional matter - but, as your wife says, let us talk in a civilised fashion over good food.'

Clearly our kind of man. And as we all made our way to my uncle's house on a hired cart - Heron crippled, Helena pregnant, me completely whacked - he even made jokes about us being borne home like a bunch of walking wounded after life's battles. And as we all made our way to my uncle's house on a hired cart - Heron crippled, Helena pregnant, me completely whacked - he even made jokes about us being borne home like a bunch of walking wounded after life's battles.

Aulus and Albia had arrived back. Vast numbers of scrolls from the Library had been recovered in Rhakotis and transferred back to where they came from, under military guard.

Fulvius and Pa, looking tense, were going out. Ca.s.sius confessed to Helena that my conniving relatives were desperate to s.n.a.t.c.h back money they had paid over to Diogenes. They wanted to find where he had stashed the cash. Knowing traders, retrieving their deposit might prove impossible. His banking would be done in cunning hideaways; the money might even already be tied up undetectably in a knotted skein of investments.

Ca.s.sius said there would be plenty of food and drink tor us to entertain our famous visitor. There was indeed, and so we had a memorable evening. It was nowhere near as formal as the night we dined with the Librarian, but all the more enjoyable for that. Helena and I, Aulus and Albia were delighted by Heron, who was so secure in his enlightened cleverness he could freely share his enjoyment of ideas with anybody who would listen.

This was the mental conjuror who invented the self-tr.i.m.m.i.n.g oil lamp, the inexhaustible goblet and slot machines to dispense holy water. Not for nothing was he known as the Machine Man. We already knew of him from his work with automata, famous devices he made for theatres and temples: noises like thunder, automatic opening doors using fire and water, moving statues. He had produced a magic theatre, which could roll itself out before an audience, self-powered, then create a miniature three-dimensional performance, before trundling away to resounding applause. As we sat enthralled, he told us how he once made another that staged a Dionysian mystery rite; it had leaping flames, thunder and automatic Bacchantes who whirled in a mad dance around the wine G.o.d on a pulley-driven turntable.

Not all of his work was frivolous. He had written on light, reflection and the use of mirrors; useful stuff on dynamics, with reference to heavy lifting machines; on the determination of lengths using surveying instruments and devices such as the odometer that I had myself seen used in transport; on the area and volume of triangles, pyramids, cylinders, spheres and so forth. He covered mathematics, physics, mechanics and pneumatics; he was the first to write down what was called the Babylonian method of calculating square roots of numbers. He collected information about military war machines, particularly catapults.

The most fascinating gadget he told us about was his aeolipile, aeolipile, which he modestly translated as a 'wind ball'. His design for it used a sealed cauldron of water, which was placed over a heat source. As the water boiled, steam rose into pipes and into the hollow sphere. As I understood it, this resulted in rotation of the ball. which he modestly translated as a 'wind ball'. His design for it used a sealed cauldron of water, which was placed over a heat source. As the water boiled, steam rose into pipes and into the hollow sphere. As I understood it, this resulted in rotation of the ball.

'So what could it be used for?' asked Helena intently. 'Some kind of propulsion? Might it move vehicles?'

Heron laughed. 'I do not consider this invention to be useful, merely intriguing. It is a novelty, a remarkable toy. The difficulty of creating sufficiently strong metal chambers makes it unsuitable for everyday applications - but who would need it?'

Eventually, it became impolite to demand yet more stories. Heron was willing to talk, a man eager to spread his knowledge and deservedly keen to report his own ingenuity. Still, he must find himself asked the same questions over and over again; that must become tedious. He could probably dine out every day of the week with devotees, though I noticed he ate wisely and drank only water. We all liked him. He flattered us by seeming to like us. Helena was particularly impressed that he encouraged us to let the children run around. 'What is the point of knowledge, but to improve the lot of future generations?'

Since they were allowed to be with us, the novelty of being amongst the adults soon palled; Julia and Favonia quickly took it as natural and were for once well behaved. I wished Uncle Fulvius had seen it. Mind you, they might have sensed his att.i.tude; things could have been very different.

Time for business.

'Heron, before we break up this delightful party, you wanted a word with me, you said - and I would like to pick your brains about a puzzle too.'

He smiled. 'Falco, we may have been beguiled by the same problem.'

Aulus jumped in: 'Marcus, are you going to ask how the Librarian came to be found dead in a locked room?'

I nodded. We all fell silent as the great inventor settled down once more to fascinate us. He certainly liked to be the centre of attention, yet had a winning att.i.tude that made his holding court endurable.

'I knew Theon. I heard about how he was found. A locked room - its lock worked from outside - and its key missing.'

'We have now found the key,' Aulus quickly informed him. 'The ancient scholar Nibytas had it.'

'Ah - Nibytas! I knew Nibytas too...' Heron let his quiet smile suffice as comment. 'I have considered deeply how this mystery can be explained.' He paused. He was wickedly keeping us in suspense. 'Could it be ropes and pulleys? Could Theon have worked some pneumatic device from within his private sanctum? Could some incredibly impractical criminal have set up a crack-brained mechanical killing machine? Impossible, of course - you would have found the machine afterwards... Besides, this is outside my sphere,' he said tactfully, 'but most murderers tend to act on impulse, don't they, Falco?' I knew Nibytas too...' Heron let his quiet smile suffice as comment. 'I have considered deeply how this mystery can be explained.' He paused. He was wickedly keeping us in suspense. 'Could it be ropes and pulleys? Could Theon have worked some pneumatic device from within his private sanctum? Could some incredibly impractical criminal have set up a crack-brained mechanical killing machine? Impossible, of course - you would have found the machine afterwards... Besides, this is outside my sphere,' he said tactfully, 'but most murderers tend to act on impulse, don't they, Falco?'

'More often than not. Even premeditating killers are often quite stupid.' Even premeditating killers are often quite stupid.'

Heron acknowledged this and continued: 'When I was told that the eminent Nicanor had been first on the scene, my mind took flight extravagantly, I must admit. I know Nicanor also -' He favoured us with his sweetest, most mischievous smile of all. 'I have often thought I would like to harness Nicanor's bl.u.s.ter.That energetic material would surely work some miraculous device!'

Heron paused again so we could all laugh at his joke.

'So do you have a theory?' Helena prompted gently.

'I have a suggestion. I will call it no more. I cannot prove my idea with mathematical rules, nor to the high legal standard you would require, Falco. Sometimes, however, we should not seek answers that are intricate or outrageous. Human nature and material behaviour may suffice. I took myself to the Librarian's room, to inspect the scene of this mystery of yours.'

'I wish I had been there with you, sir.'

'Well, you may visit again and test my ideas at your leisure. I propose nothing complicated. First,' said Heron, making it all sound so logical I felt ashamed not to have seen this myself, 'over the centuries, the great Library has suffered many times from the earthquakes we experience here in Egypt. 'Young Albia squeaked and bounced about; Aulus nudged her quiet. 'The building has withstood the shocks -' He chortled. 'So far! One day, who knows? Our whole city lies on low land, scored and silted by the Nile Delta. Perhaps it may yet slip into the sea...' He fell silent, as if troubled by his own speculations.

It was Aulus who worked out where the original comment had been heading. 'The doors to the room stick - one very badly.'

Heron revived. 'Ah, excellent young man! You catch my drift. The door sticks so much, I myself could not open it. Earthquake damage has shifted the floor and doorframe; routine maintenance has failed to address this problem. Were that my room, I should devote myself to arranging some system of artificial exodus, in case I found myself trapped one day...'

'So you think Theon found himself stuck?' suggested Albia.

'My dear, I think he never knew the doors had been locked. I suspect his death was entirely coincidental to what happened with the key.'

'I am more and more inclined,' I said, 'to call Theon's death a suicide.'