of conjecture and experiment have taken humanity? No point in trying to answer that one. None either in thinking what might have happened, even granting the ethical bias of his teachings, if he rather than Plato and Aristotle had won the battle of the books for the human mind.
‘Quickly – come out with me!’ Meekal gasped. He clutched at my arm and hurried me into the bright, fresh air. I blinked in the sun and breathed in and out as the clouds that had, so insidiously, gathered about, drifted from my head.
‘Thank you, my dearest,’ I said, leaning against the side of my carrying chair. ‘You do have to be careful about those fumes. And they will be gathering faster before the process stabilises. Now, do be a love and fish out some more of that beer. As Silas is standing with his face to the wall, and these slaves can’t see a thing and don’t know Greek, I suppose you might care to join me in some refreshments.’
We drank. I rested. I watched the vultures overhead; doubtless Meekal’s latest victim had parched or suppurated to death. I thought about his reference to ‘supplies’. Did this mean he’d found another place where oil oozed from the ground? If so, the cellars that stretched far beneath us would be filling up with more of the basic materials. I turned and explained again to Meekal the need to filter the oil twice before it was finally sealed into the large earthenware containers to settle. He nodded impatiently. That much, at least, I had impressed on him.
The sun was now at its highest point, and I cast barely a shadow on the ground. Even with half a pint of coolish beer to keep me going, I didn’t fancy hanging about too long in the open. I nodded to Meekal. He pushed the door shut and called Silas over. We locked. We signed. We countersigned. Meekal now applied his Governor’s seal. We passed back through the gate into the first zone.
I’ll not bother with describing my inspection of the combustant. There never had been any problems with making this. It was simply a matter of unstopping one of the big jars and sniffing to make sure all remained well. The attendant security measures took far longer than the inspection. At last, we were back into the first zone, where Silas had ordered a most welcome lunch for me of bread in milk and olive paste. While I ate, Meekal gnawed at a crust and went with Silas through all the many ledger entries made since our last visit. All was in order. Still, he sniffed about – questioning bread consumption, asking about the burial of the workmen who’d not survived the last explosion, testing to make sure he knew the names and faces of every single guard.
Now, the break was over, and it was time to inspect the fourth zone, this entered through a gate at the far end of the third zone.
‘If not in writing, I gave precise instructions about the size of these openings,’ I said with rising impatience. I had my visor up and was looking through my lenses at the double valve that the straining workmen held before me. ‘It must fit exactly over the two spouts of the joined kettles, and the opening of each valve must allow the correct quantities of vapour into the mixing chamber. Again, the single exit spout must be of a certain diameter. It needs to fit precisely over the final bronze projection pipe. I’ll not fault the hardness of the steel – after all, this is Damascus. But this thing as it stands will simply produce another explosion.’ I replaced my visor and stood back to see the abortion that had emerged from fourteen days of labour in another of the sealed zones. It was a ball with about the same volume as a large cooking pot. The two feeding spouts were probably the right size and distance apart – we’d see about that in a moment. But it was plain, even without a measuring rod, that they weren’t long enough to fit safely within threaded sleeves on to the kettles. The exit spout was also too short. And it was too narrow. The bronze projection pipe really would pop straight off – that, if we didn’t have an explosion from the backed-up mixture. It really would all have to be redone.
‘Oh, never mind!’ I said with a sly look at Meekal’s face. No doubt, once my back was turned, there’d be an explosion of his own all over those useless buggers in the valve workshop. For the moment, the valve wasn’t critical. ‘I suppose you’ve fixed up a demonstration already for His Majestic Holiness when he rolls in,’ I added. ‘This being so, you’ll need to work those Syrians double shifts to get the job done properly in time.’
I turned my attention now to the big double kettle. This was a huge contraption. It would have filled one of the larger rooms in the Tower of Heavenly Peace. At least this time – and I was looking at a third attempt – my instructions did seem to have been followed to the smallest detail.
‘There’s no gap,’ Meekal said hurriedly, ‘between the inner bronze chambers and the outer casings of iron.’
I looked again and grunted. We’d see very shortly how well they’d been fitted together. I held up my lenses again and looked closely at the welded joints where the cylinders had been sealed at each end with five-inch thicknesses of iron. Those were the real weak points. We’d see what extra strength the brass retaining bands would give. I looked at the repaired and now reinforced wall that would protect us during the experiment. It was a miracle we were both still alive after the fiasco of our July experiment. Now, I was glad of the sandbags that would spread the force if there were another disaster.
While the valve was fitted to the double spout – yes, there wasn’t quite enough thread for the sleeves to get a proper hold – I tapped both kettles with the silver head of my walking stick. They sounded as if they’d do. Once it was fixed in place, I tapped the steel mixing valve. The ratio of wall thickness to volume didn’t let me tell much at all from the sound. Nevertheless, I did test the basic security of its fitting to the kettles.
I took my seat beside the kettles and nodded at Meekal. He gave an order to the workmen, who then lit the fire. With air from the bellows, the charcoal was soon an intense white even in that scorching sunshine.
‘I didn’t think to ask you,’ I said with sudden alarm, ‘if both kettles are filled half with water. It needs to be neither more nor less than half.’ Meekal nodded. Relieved, I sat back and waited. I had another headache coming on. It might have been the fumes. Just as likely, it was all the beer. Meekal stood beside me. Neither of us spoke as we watched the nervous pumping of the workmen on the bellows. I put up my ear trumpet and leaned forward again. ‘I think it’s boiling,’ I said in Syriac. One of the workmen nodded. ‘Then do please screw on the lids.’ He bowed and began fumbling with the eight-inch brass discs that would seal both kettles. I got up and let Meekal carry my chair behind the protective wall. As the workmen hurried round to stand behind us, Meekal bent down and pulled out the stopper on the water clock.
‘But tell me again, my dearest kinsman,’ he asked, now speaking Latin for added security, ‘why the kettles are only to be filled halfway.’
I sniffed and looked at the dribble of water from the clock. It had already reached the first marker in the collecting bowl. I’d decided we had to wait until it reached the fifth.
‘Your lack of attention to these matters disturbs me,’ I replied. ‘The purpose of dividing the work as we have is to ensure that no one person – indeed, no group of persons working together – shall be able to reproduce the Greek fire. The plan is that you, and only you, will have the overall knowledge needed to make everything work. Now, that really does mean you need to understand what is happening.’ I held up a hand for my cup, and waited while it was filled with iced lemon juice. ‘The idea that Greek fire is a burning liquid is an error that I have deliberately cultivated. In fact, if these kettles were to discharge their contents as a liquid, I don’t see how the flame jet would be longer than a few dozen yards, and it would all be used up in a single burst. The truth is that all materials exist in three forms: as solids, as liquids, and as vapours. Each state depends on the amount of heat applied to the atoms. The greater the heat, the looser the atomic structure.’
‘So you’ve said,’ Meekal sneered. ‘But this does conflict with what I’ve read in Aristotle.’ He smiled at the involuntary tightening of my face. ‘He says that fire is heat and dryness. Water is cold and wetness. Steam is made by combining the heat of fire and the wetness of water. The product is air and earth. All my teachers in Constantinople were of that opinion. And I have read the same in that book you so kindly gave me.’
I breathed in and out very heavily. I took off my visor and looked at the questioning face. Was the man taking the piss? Of course he was. I forced myself to relax and drank more of my lemon juice.
‘If you don’t wish for a public beating,’ I said coldly, ‘you’ll keep your mouth shut about that man and his equally deluded followers. According to Aristotle, none of this is even conceivable – unless you call in the “intellectual” support of magic. Now, unless you have something sensible to add, I suggest you shut up and wait.’ I took off my hat and wig and mopped my sweaty scalp. I looked again at the clock. Another two markers to go. I dropped the wig into my lap and replaced the hat.
‘Epicurus was wrong when he said that there are atoms of heat,’ I said, breaking the silence that had resulted from my last comments. ‘I think it more likely that heat is a kind of motion, the communication of which causes atoms to vibrate within their structures. Whatever the case, the furnace under those kettles converts their liquids to vapour. These two vapours then mix together in the bulb of the double valve and become explosive. When they are lit, it is burning vapour that shoots out. Because Greek fire is a vapour and not a liquid, these kettles can
