‘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 be used and reused throughout an entire battle without any need for recharging.’
I fell silent again and watched the clock. We were almost at the fifth marker. I was now sweating heavily. I was also beginning to shake with the tension. The valve excepted, all had gone perfectly this time. I didn’t want another anticlimax. The water level had risen to the fifth marker in the bowl. It was now or never. I took up my walking stick and got slowly to my feet. I peered cautiously round the wall to the double kettle. It was beginning to shake, but I could hear none of the bright hissing that would indicate a failed joint. I turned back and smiled at the head workman. He swallowed and clutched at the silver relic case about his neck. I continued looking round the wall as he walked forward and began tapping with his long crowbar at the brass plug screwed into the exit spout of the mixing valve. I could hear Meekal groaning away behind me in some stupid prayer. Incongruously, the other workmen beside him were calling desperately on Christ and the Virgin; surely, if they had any say in the matter, we’d have a catastrophic explosion that took us and all our achievement straight to Hell. But I put the human noise out of mind. I pushed in my hearing trumpet and listened intently. Yes, I could now hear the high whistle as the plug reached the last turn of its thread. I rapped the wall smartly with my stick and called out a word of encouragement to the workman. With a last cry of fear and pleading, he brought his bar down with a firm tap on the spout, then threw himself down. I pushed sweaty palms against the wall and took a deep breath.
Chapter 56
With a deafening ‘whoosh!’ the combined jets of invisible vapour shot across the hundred yards of clear space in front of the kettles. I saw the wooden screen placed by the wall go back, and heard its dull clatter against the stones of the wall. I breathed out and pushed my head further round the wall to see the kettles. They hadn’t exploded, but the first charge of vapour was spent, and it was now steam and water shooting forward. As I looked, the kettles began to shake and rattle about in their housing. As I pulled myself back behind the wall, I heard the cracking of support beams within the stuttered scream of the discharged steam and water. I felt the impact of the kettles as they flew backward into the sandbags, and then the warm spattering of water that rained down on us.