By Schism Rent Asunder (84 page)

“I can see that,” Merlin agreed, manfully resisting the powerful temptation to smile.

“I'd gotten that far,” Seamount continued more seriously, “when it occurred to me that there was no need to light the fuse by hand if I could use the gun's muzzle flash to do the same job, so I started trying to come up with a fuse which could be ‘self-igniting' and give a reasonably reliable and consistent burn time. I've tried slow match and quick match, and I've tried other approaches, as well. The one that seems to work best, at least in tests, is a hollow wooden plug filled with fine-grained powder. We've finally managed to come up with a composition which actually burns at a predictable, reliable speed, and by using a fairly thin-walled plug, we can actually select for different burn times. We've discovered that if we mark the outside of the plug in increments and punch a hole through it so that the fuse's powder train ignites at a different point in the fuse channel, we can adjust the interval between firing and the shell's explosion with a surprising degree of accuracy.”

In this case, Merlin knew, “we've” actually meant “I've,” and he folded his arms as he allowed his own expression to match the Charisian's increased seriousness.

“I can see where that would have been difficult,” he said. “From what you've already said, though, I suspect that isn't the real problem.”

“No, it isn't,” Seamount said with what Merlin recognized as massive restraint. “The problem,
Seijin
Merlin, is that it doesn't matter how reliably the fuse can be timed if the propelling charge keeps blowing the damned fuse
into
the shell and setting it off
inside
the gun!”

“Oh!” Merlin nodded, tugging on his mustache again. He frowned in obvious thought, although he wasn't thinking about exactly what Seamount might have thought he was. The difficulty lay less in solving Seamount's problem than in managing to avoid solving it too quickly.

“Let me see if I have this straight,” he said, after several seconds. “You don't want the gunner to have to physically light the fuse on these ‘shells' of yours for every shot, so you've developed one that the propelling charge's flash ignites. And from what you're saying, the fuse you've come up with lets you time things with a reasonably accurate reliability … when it works at all. But when the gunpowder behind the shell goes off, the fuse is a weak point in the shell wall and it goes off prematurely?”

“Basically, yes.” Seamount shrugged. “For quite some time I wasn't certain whether the shell wall was fracturing around the fuse, or if the fuse itself was simply being blown bodily into the shell's interior. I suspected that it was the latter, but since no one's had any experience with this kind of projectile before, I couldn't rule out the possibility that the shells I'd designed simply had walls that were too thin to stand the shock of firing. There was no real way to tell from what was left after the shell exploded, so I tried firing a couple of hundred shells with solid plugs instead of fuses. The rate of premature detonations went down enormously, but they were still occurring, so I sat down and thought about it for while.

“Eventually, I realized that at least part of what was happening was that the gunpowder filling was moving inside the shell cavity when the round was fired, and the friction heat that generated was causing the premature detonations. So I tried stabilizing the charges by pouring in hot tar to hold everything in place. I had to be careful to preserve an open channel for the fuse's flash to reach the main charge, but that wasn't too difficult.

“After I started using the tar, we got no more premature detonations … as long as we stuck with the solid plugs, instead of using live fuses. That seemed like pretty conclusive evidence that the shell wall was strong enough, but I wanted to be sure. So, I filled several dozen shells with flour, instead of gunpowder, put live fuses into them, and fired them into shallow water where divers could recover them. When I examined them, it was obvious that the fuse itself—or enough of it to do the job, at any rate—was being blown into the shell, but that the walls weren't cracking under the stress of firing, which confirmed my suspicions about the cause.”

He paused for a moment, his expression that of a man torn between satisfaction that at least a part of his design had proved workable and that he'd devised a technique for proving that it had, on the one hand, and frustration over his inability to fix the part of the design that
hadn't
proved workable, on the other hand.

“It doesn't happen every time, of course,” he said then. “But it does happen a lot of the time, and getting gunners to adopt something this newfangled is going to be hard enough even if they're not afraid each shell is going to explode either inside the gun or the instant it clears the muzzle. It's just a little difficult for them to feel all warm and happy about something that's likely to
kill
them, you know.”

“Well, yes, I can see that, I suppose.” Merlin smiled slightly. Then he tugged on his mustache again, his smile turning into a frown as he pondered.

“Tell me,” he said finally, “from what you've just said, it sounds as if you were loading the guns with the fuse hard up against the propelling charge.”

Seamount nodded, and Merlin raised one eyebrow.

“Have you considered loading your ‘shell' with the fuse facing
away
from the propelling charge, instead?”

“What?” Seamount frowned.

“I asked, if you'd—”

“Just a minute!” Seamount's raised hand stopped him, and the stubby commodore's eyes narrowed as he thought hard and furiously, indeed. Then he started nodding. Slowly at first, then faster and faster.

“Of course! I should have thought of that myself! The flash from the propelling charge sweeps all the way
around
the shell, doesn't it?”

“I'd certainly think so, at any rate,” Merlin agreed.

“Of course it does! And if it sweeps around and lights the fuse in the front instead of hammering it into the shell cavity from the back.…”

Seamount stepped over to one of the slate-covered walls, snatched up a piece of chalk, and began jotting notes to himself. He read over them, shook his head impatiently, erased one line and chalked a correction, then nodded and looked back over his shoulder at Merlin.

“You're a very useful fellow to have over on a visit,
Seijin
Merlin,” he said dryly. “Somehow, you always manage to point me in the right direction, don't you?”

“One tries,” Merlin murmured.

“Oh, one certainly does,” Seamount agreed.

“Was there anything else I might help you with, My Lord?” Merlin asked, sounding as little as if he were changing the subject as he could manage.

“Actually, there are two other problems I wanted your opinion on.”

“Of course, My Lord.”

“Both of them have to do with the new rifled guns,” Seamount began. “I've tried several approaches to getting their rounds to take the rifling. One that seemed promising was to encase the projectile in a soft metal, like lead, that could be forced into the rifling much as we've done with the new rifle bullets. Unfortunately, the lead keeps stripping off and the rounds don't take the rifling consistently.

“One of my bright young assistants suggested that what we might do was to cut the cannon's bore like a helix, so that it was twisted itself. Not a round bore, you understand, but something a bit more trapezoidal that twisted around its own central axis to force the shot to spin without requiring rifling at all. Frankly, I think that would probably work, but I'm concerned about bore erosion. Which is why I'm still convinced that some form of grooved rifling is the answer; it's just a question of figuring out how to make the shot physically engage with the grooves.

“So far, the most promising thing I've tried is to cast the shot with metal studs.” Chalk cracked like a staccato explosion as he tapped one of the diagrams on his wall. “As you can see, the idea is that when the gunners insert the shot into the muzzle, they engage the rifling with the studs. Then the shot rides down, rotating as it goes, until it comes to rest against the propelling charge. When it's fired, the studs ride back up the grooves, which imparts a rapid spin to the shot, and off it sails to its target.”

He turned back from the wall to smile fiercely at Merlin, and Merlin smiled back.

“The problem is this,” Seamount continued, his smile fading slightly. “First, as we'd expected from the beginning, bronze is too soft, especially using the stud-and-groove system. The insides of the barrels simply shred after only a very few rounds. Secondly, I've already discovered that even with the stud-and-groove approach, bore pressures are rising dangerously.”

“What do you mean, ‘even with the stud-and-groove approach'?”

“I expected bore pressure to go up drastically when I tried the lead coating system. After all, the shot was sealing the bore a lot more thoroughly, so it was inevitable the pressures would go up, the same way they went up in the rifles when we started using hollow-based bullets in them. But I'd rather hoped that enough of the propelling gases would be able to escape around the shot, which is smaller in diameter than the bore, using the stud system. Which, by the way,” he added parenthetically, “is one reason I'm irritated with myself for not realizing those same gases could ignite the fuse on their way past the shell. Anyway, I'd hoped the windage between the shell body and the bore wall would let the gases escape and relieve the pressure.”

“I can see that,” Merlin acknowledged.

“Well, I suppose at least some of the gases are doing just that,” Seamount told him. “Unfortunately, I don't think enough of them are. And there's another factor, too—one I hadn't really thought about initially. The shells we're developing for the existing smoothbores are the same size as the round shot they already fire, and because they're filled with gunpowder rather than solid iron, the shells are actually lighter than the shot the guns were originally proved for. But in a
rifled
gun, the shot doesn't have to be round. In fact, you don't
want
a spherical round. Since a more cylindrical shape lends itself more efficiently to rifling, anyway, you end up with an elongated projectile. For an explosive shell, that will give me a larger internal cavity, which means I'll be able to pack in more explosive, and the fact that it's hollow will tend to hold the weight down, at least to some extent. For a solid shot, though, the overall weight of the shot goes up very sharply, and even with a gunpowder filling, a properly designed shell strong enough to stand the shock of firing without disintegrating is going to have thick enough cavity walls for it to weigh more than a round shot for the same gun. And that greater weight means the gun has to work harder to throw shells at the same velocities at which it throws round shot, and that drives up bore pressure, too.”

“All right,” Merlin said, nodding to show he was following so far.

“We can cast iron guns and then cut the rifling grooves into them,” Seamount said. “On the other hand, we've already got hundreds—thousands, actually—of the new bronze guns. I'm sure we could find something else to do with all of that bronze, but it seems an awful pity after we've gone to all the trouble of casting them in the first place to simply throw them away—as artillery pieces, I mean. That's one problem. The other problem, frankly, is that cast iron is a lot more brittle than bronze. I'm not sure it's going to be up to the stresses that are going to be exerted once we start casting large-caliber rifled guns. Not without going to truly enormous pieces—probably at least as big as or bigger than the old Great Doomwhale.”

Which, Merlin reflected, had weighed almost six tons.

“But what would you use instead?” he asked aloud.

“At the moment, I'm thinking in terms of wrought iron,” Seamount replied, not to Merlin's great surprise. “It'll be expensive—even more expensive than bronze—but Master Howsmyn says his ironmasters are equal to the task. I think he's probably right about that, but producing reliable wrought-iron gun tubes is going to be expensive in terms of manufacturing
time
, as well.”

Merlin nodded again. He wasn't surprised by the difficulties Seamount had encountered. Indeed, if he was surprised at all, it was by how quickly the Charisian had experienced them. Which was foolish of him, he supposed. If Sir Ahlfryd Hyndryk had demonstrated anything, it was that his mind was every bit as quick and focused as Prince Nahrmahn's, if in very different directions.

The problem, as Seamount had just pointed out, was that cast iron was brittle. Safeholdian foundry techniques were remarkably advanced for a culture where steam power had been prohibited, yet they still weren't up to mass production of steel by a considerable distance. The technology itself lay within their grasp, but there were still obstacles to be overcome.

The fact that Safeholdian foundries had been using waterwheels for centuries helped, but it was only in the last few decades that men like Edwyrd Howsmyn and his “mechanics” had begun applying power to the process more generally. Initially, the waterwheels' only true function had been to power blowers to raise the temperature in Safeholdian blast furnaces and fineries. The processes for turning blast furnace iron into wrought iron and steel had been no further advanced than perhaps 1700 Europe.

Howsmyn had been one of the pioneers—all of whom had been located right here in Charis—who had championed replacing charcoal with coke made from the kingdom's generous quantities of coal. He'd also taken the lead in developing what had been called the “puddling process” back on Old Earth, with the result that
his
foundries' output of wrought iron—very high quality wrought iron, in fact—was several times that of any other foundries on Safehold. But even though that was true, wrought iron was still more expensive, primarily because of the greater amount of labor, processes, and time involved in its manufacture, than cast iron.