With all the workers but Urika back in town, and shipments of iron starting to flow again, Vonn got busy. There was a meeting with wizard Ralator to make, and work to catch up on. Kotta was occupied in his own way by heading north on his own, seeking Selen.

The engine prototype came together. Vonn looked skeptically at the milling machine, which he'd been cursing out and trying to improve even while using it. "Yeah, okay, it's useful."

"Now hug it," Tazo commanded. Birb chirped.

Vonn showed the mechanical cutter some paternal affection. "So, let's try the new engine. Crystals, please?"

They had a set of magicite pieces requisitioned from the Baron. Vonn tuned some to cold and Tazo made the others give off heat. With a nudge the machine lurched to life, whirling and pumping air up and down within its cylinder.

Vonn watched it go. "Come to think of it, it's not that different from the simple kind of nuclear reactor. Imagine the crystals are replaced with a chunk of magic hot metal that poisons you if you get near it."

Tazo said, "I like our version better."

They measured the device's weight, its speed, its power. How much force could it apply to a little drive shaft and still turn? Vonn then went over the crystals with his personal ability, Crystal Integration. The magical effect made the gems pump out more heat and cold at once until the engine's top began to glow dim red and its underside to grow frosty. Its wheel spun more insistently.

"Oh!" said Tazo. "I took the Crystal Integration power for my new Mage level. So now you have backup for that part." Her latest advancement put her at Mage 4, Engineer 2.

"Great!"

Vonn did an estimate of the math in his head but looked to Birb to confirm it. She said, "The power is slightly better than your first model since it's better made, but since it's not using your special lightening method" -- the antigrav effect no one understood -- "the weight is too high to fly." Her wings drooped.

Vonn had thought so. "The plane itself can be improved, too. What's our current reading on the antigrav stuff?"

"Weight reduction by eighteen percent." They'd been taking it out of storage often for measurement, confirming a slow exponential decline. "With that amount and the improved design, you could still make it fly, if you used the gold crystals to boost the output further."

It'd get less viable over time, though, if they waited long enough to have the antigrav material weaken even more. Tazo echoed his concern, saying, "So with the improved design and Crystal Integration boosting and gold gems that have better output, that still barely gets us off the ground without antigrav."

Vonn added, "And that's with my personal Well of Energy power to make the pressure cylinder sturdy, and Harmonious join to reduce friction, on top of the Crystal Integration. We used lots of gimmicks. I want this to work with as few of those as possible."

Tazo paced. "I want some other ability to throw at this to get another few percent. We know it can work. We just need to make it practical without the one effect nobody knows how to replicate yet."

"Let's take measurements of the power output with different crystal positions and numbers."

That was busywork but important to document. Tazo commented, "I would've liked to get some new power that can stack atop all of yours, but nothing stood out. I turned down an option for raw spell output, as though my goal were to blast monsters a little harder."

"Probably wise."

"I do want to make a better wand though, or get someone to craft one."

Vonn smiled. "I do need practice at this enchantment power."

"You should make yourself one too. A good wind spell might help with the pressure cylinder."

Birb had been scribbling equations on the board. She'd really picked up on the math and physics since Vonn had given her a very basic balance-of-forces quiz. Now she had added another upward force to the design. "Then isn't it time to team up with Selen on a balloon ship, pushed by propellers?"

Vonn said, "I would be all right with this idea. The key would be to get a balloon with enough lift to carry the engine, the pilot and at least a token cargo or a passenger. The engine's power doesn't need to be enough to provide lift, only to move it. The speed will probably stink though."

"'Proof of concept', right?"

"Well, yes, that's important. But we do need to start moving beyond sheer bragging into being useful."

Tazo gently reminded them, "And we have specific orders for a set of engines, from the boss."

Vonn wasn't thrilled about thinking of the Baron as his boss. He muttered, "He who pays the piper, calls the tune."

#

He sent the team's letter to inventor Firefern on its way to the south. With it he enclosed a second letter for the unexpected fox. He started a first draft that was completely foolish, threw it away, and tried again.

"I'm Vonn from Shieldpoint. In the System's judgment I'm seventeen with four levels of Engineer and three of Mage, and I'll be earning a fifth in Engineer this winter. So you do a mix of things? I like that. My older sister is a Mage and Engineer, and my friend Selen is an Alchemist and Mage but knows more than you'd think about machines too." He talked a bit about Polestar and Kotta.

"It's been an eventful year and a half for me. I met Selen at Tukka's Hollow when the dungeon core had just reappeared and we helped the locals get everyone out. That Aves really does know things about another world -- and so do Polestar and I, in our own ways. That's been the inspiration for some of our work. You might find us all a little strange."

He grinned as he wrote. Would she consider him and his friends to be the good kind of strange? He chose his words carefully. "My main goal is to bring innovation. Discovery. The idea of making things better. That's why I want to meet more people interested in that, from any angle, and build things in greater number so that we commoners can use them too. If you're looking for business opportunity, we could use sturdy heat-resistant cloth in huge amounts for the balloon project, and Selen's starting to sell dyes."

"But of course work isn't everything. That's some nice art you sent! I mostly just draw technical pictures, though I'm getting into storytelling and music. My friends and I know songs from a very distant land. I'd love to see more of the world including Liiros if I can ever find the time, but I'm wary of how long it'll take me to get back to my workshop and I have a lord to keep happy!"

He asked about her home and family, talked about village festivals and local gossip, then wrapped up. For this letter he'd used a page on which one corner held a sketch of himself, signed by the artist he knew in his Baron's territory. He'd long ago accepted that the fuzzy face he saw in basins of water was his, but it still felt odd to see it drawn.

Would the letters even arrive, or would they get eaten by chompers or scattered to birds' nests? A lot might hinge on the fate of scraps of paper making it south along a river, and he hesitated before handing them over to a semi-trustworthy boat captain. That method was the best he could do for now.