Chapter 40: Seeds, Cattle and Iron III

Somewhere in the middle of the next day, Eivind mentioned, out of nowhere, some of the things he had seen when he'd been to the southern countries.

Wheels driven by a stream of water, turning a stone, grinding grain without anyone laying hand on it. Hiccup had been thinking about the concept ever since.

Eivind had mentioned it was a mechanism involving a wheel set upright in the current, some paddles round the rim to catch the push of the water, a shaft off the axle, and a set of gears inside the mill to bring the turn down to the stone.

The trick of it was simple enough.

That reminded Hiccup of something. He knew a place.

There was a river running through the grasslands of the island, day in and day out especially after winter, when the ice and snow from the mountains was all melting.

I wonder if I could build something similar there.

He must have said part of that out loud without meaning to, because Eivind was looking at him, "That would take some iron," he chuckled.

"Well, some. Not as much as you would think, actually, most of it could be done with wood."

Eivind was drawing on the deck with a wet finger now.

"The shaft is the problem, and the gearing. I do not actually know how to cut a gear," he admitted.

"But I do."

Eivind stopped drawing.

After that neither of them shut up for the better part of the day. They drew mills, a hammer driven off a waterwheel, and some bellows that worked themselves, none of which existed anywhere but on a wet plank.

Later that same afternoon Eivind worked up the courage to ask about the rig.

"How did you even come up with that tail fin?"

"The what?"

"On the dragon." Eivind pointed vaguely astern, in the direction of the island. "The thing on his tail. I have seen it from below. There is some weird linkage in it, and it moves. I cannot work out how it moves because you are usually not around when it does."

Hiccup looked at him.

Not the question I was expecting.

But Eivind's interest seemed plainly genuine, there was nothing dangerous in the answer, and there was a long grey afternoon ahead of them.

So he asked one back.

"I can. But which one?"

Eivind frowned as he leaned in.

"There is more than one?"

"There have been around five official ones so far."

Hiccup sat down against the rail.

"So which are you asking about, the manual rig or the autonomous one he wears now? Because they are not the same and they work nothing alike."

Eivind, who had been dutifully coiling a rope for an hour, put the rope down.

"Then start from the beginning."

Ah.

Ah, well. This is going to take some time.

So Hiccup began explaining a little bit at a time.

Not the mechanism itself, not yet. The shape of the thing first. What a tailfin did on a dragon, why one design was not the same as another, why the loss of half of Toothless's had grounded him at all.

Emerald arrived about five sentences in, with a blanket wrapped round her shoulders. She sat down against the mast with her knees pulled up and made no attempt whatsoever to look as though she could understand any of it.

"The manual rig works on a simple idea. A pair of cables running down the spine under the scales, in a channel cut into the saddle, here."

Hiccup drew the saddle with a stub of charcoal they found lying around.

"It is framed so it does not chafe, and there is a stirrup at the front worked with the left foot. Push down, the fin opens. Let it up, it closes."

Eivind took a while to think over that.

"So you have to be on him for it to work."

Hiccup nodded. "Every single second. That is the great flaw of the manual rig."

He rubbed his jaw.

"He could not fly without me. Not for long. So if I came off him at a thousand feet, we both went straight into the sea."

Eivind and Emerald both looked up at the casual way with which he described a mortal fall.

They nodded slowly.

"That must have been insane to pull off. How many versions did it take to get it right?" Eivind was not being polite. He genuinely wanted to know.

"Well." Hiccup made a vague gesture. "The first was a fixed vane. It was useless. He could glide, and that was about the whole of it. He also hated it, and he was kind enough to let me know."

"Let you know?"

"He crashed us into a tree."

The flat look on his face said he had not entirely forgiven it.

"The second was three positions and a catch." He drew the old design. "Climb, dive, level. Nothing in between."

He grimaced.

"Which meant he could not turn properly, which meant every single landing was a controlled crash. Let me tell you, it was not pleasant."

Eivind paused, plainly trying to picture what that would look like.

"The third version was actually pretty clever. It was continuous. A worm screw off the stirrup, so the fin could sit anywhere in the range. It was a beautiful piece of work and it took me a month, I was extremely proud of it."

A long pause.

"Then it seized in the cold at a thousand feet, and we found out together what a Night Fury does when his tail stops working." He let out a long sigh, "Which is mostly just thrash around in the air with his tongue out. While I desperately try to save us from death."

Eivind winced.

"The fourth design was stupid. It is the only manual one that ever properly worked."

Hiccup laughed at himself a little as he sketched.

"A cam and a friction plate, here. The whole thing is actually loose so it rattles. It is a worse machine in every single way. It is also simpler, and yet it will hold any angle, it never seizes. Perhaps because there is nothing in it tight enough to seize."

He shook his head.

"Every clever thing I have ever built nearly killed us. There is a lesson in that somewhere."

Eivind nodded.

"Sometimes the simpler answer is the right one," he nodded. "My father's mill often had a trouble like that with a spindle. They fixed it every time by making the bearing sloppier."

Hiccup stared at him.

"Uh, say that again."