In the days that followed Jared paced about his room, hammering at the problem until his head ached. Several times he rode into the countryside for peace and solitude. He had caught what Rosamunde was saying: that offering the huo yao on its own would get no interest. What was needed was a ready means of using it, a saleable thing of sorts.
But what? The clay pots were impractical in England. The only thing he could think of was to put them into a mangonel and throw it at the walls. But this would not do the job – stones lofted high came back down at a sharp angle then glanced off. This method would end with the pots shattered.
It was a conundrum. Any device to throw the pots would not work. There had to be an answer.
And it came to him in a completely unexpected way.
Outside in the street, children were playing noisily in bursts of glee at some devilment. He crossed to the window to shout down at them, and from his viewpoint saw that one lad was hiding behind a horse. He was wielding a powpe, a small toy that he was using to shoot peas at his unsuspecting friends.
Jared opened his mouth to bellow at the children but in a sudden flash of insight he saw something that left him speechless.
The powpe was simply the stem of some plant with the pith removed, leaving a smooth tube. A pea was inserted at one end and with a mighty puff at the other it was sent on its way.
If instead of a boy’s huffing it was the huo yao doing the work, then judging from the violence he’d seen in the ravine, the pea would rush out as if all the demons of hell were after it.
He thought feverishly. This was more than possible – and if the whole thing were scaled up, instead of a tiny pea, a great rock like those of the mangonel could be used. And these like the pea would hit the walls straight and direct in a smashing strike that no castle could withstand!
At the awesome vision he had to sit and calm himself.
The device should contain all the power of the huo yao, letting it exit just one way – by forcing out the ‘pea’ from one end only. So was that all? A tube closed off at one end? It would have to be strong, very strong – made of iron, in fact.
He’d start small, a ‘pea’ the size of a grape perhaps, just to test the principle. This would define the size of the instrument. About a foot or two long and a bore no greater than an inch.
Fill the thing with devil’s dust, drop in a grape-sized object, point it towards the foe and set it off.
But his blacksmith’s craft told him that making it wouldn’t be quite so straightforward. In his experience there were plenty of articles in the form of a tube, such as the socket on a scythe blade to take the wooden haft or a halberd’s affixing to the spear shaft, but all of these were short and shaped at the horn of an anvil. Nowhere was there a need outside lead plumbing for a continuous length of pipe.
In the absence of a parallel-sided mandrel for interior shaping there was no other recourse than hand beating: a rectangular iron plate, heated at the edge then upset back on itself until it had been rolled into a pipe. Then forge-welded along the seam with one end crimped off.
In his mind’s eye he saw his iron tube and filled it with devil’s dust, dropping perhaps a child’s marble on top. Then he’d only need to …
How was he going to get at the devil’s dust to set it off?
A long thread burning from the open end? It couldn’t get past the ‘pea’, for the devil’s dust was by definition sealed off from the outside world.
He bunched his fists in frustration but the solution soon came.
If he needed to get at the huo yao, he’d have to make a discreet passageway to it – spike a hole to where it lay inside, and let the fire rouse it to action.
For the rest of the day he tested the idea in his mind, tracing through the stages one by one, and could see no gaps in his reasoning. Yet if he went on with an expensive smithy job and he’d overlooked something it would be the end for him – Rosamunde would lose faith in his abilities and call a halt.
Jared was confident of the ironwork but would the huo yao behave as he’d predicted or under forced restraint would it just lie there sullenly? He had to find out before going any further.
He’d make the thing cheaply out of fired clay and wound around with iron wire, as Marcus the Greek had said.