"What are those moving things?"

"They're..." She searches for a good word in her language, finds none, and decides to just use a loanword. "Buses. They are machines used to go from place to place, they burn fuel and somehow turn the heat that produces into motion. I don't know the details. There are also trains, which are like longer buses that move on rails, and cars, which are like buses but owned by individuals instead of the city."

"Huh," says Crystal. "That sounds useful."

"They are useful! Something like two hundred years ago, some enterprising soul wished for a good way to move things from one factory to another, and then he know how to build a steam train, an early kind of train named that way because steam is what made it move. Buses and cars came later. It's apparently a bit of a problem getting enough fuel for them all, but they're more than useful enough for that to be worth the effort."

"What kind of fuel do they need?"

"In theory anything that burns will do, but most things will break if you try to use, like, wood. Most things use a liquid called gasoline, I think they mine for it? Oh, there's also a sort of liquified oil-alcohol mixture made from starchy crops that's not very popular because it's cheaper to have someone wish to refill all the mined-out gasoline."

"You might be good enough at troportation to do liquid quantities, now that you can."

"I'll definitely try it later, but right now I'm going to get you four on welfare. I'm unsure if they'll treat you as two people or four... Physically, you have the needs of two people, plus you need some mice. Well, exceptions can be made, I'm sure."

"We're not going to be here that long and we have troportable nonperishables, but non-troported food would be nice," sighs Crystal.

"What's the other thing?" asks Crystal.

"Troporting sizes mostly only works between things that are at least sort of the same shape," says Crystal. "I mean, Holly thinks she could do a necklace and a candlestick but I probably couldn't."

"Would squares or bars work better, then?" The bus moves forward, then turns left. Pretty quickly. Erin grabs a rail to avoid being tossed around.

The visitors were not expecting this and do get tossed. Lightning catches Crystal, who blushes. "Um," she says, "yes, if both things were squares or bars. So you don't just want a little candlestick or a big necklace?"

"Sorry, forgot to warn you about the jerking around. No, what I want is more gold and more silver."

"Well, then it would be easier just to swap the materials," says Crystal. "If you don't mind having your gold in candlestick shape."

"No, that won't matter." Now the bus is going over a very impressive-looking bridge, which is over a wide river containing several ships.

"What are you going to do with the gold?" asks Lightning.

"It's more valuable than iron, here. I'm going to sell it. This won't work forever, of course, once troporting is semi-common supply and demand will even it out. And if I don't cash in on magical arbitrage, someone will."

"Oh, I guess without troporting that kind of thing would happen," muses Crystal.

"Abusing economics with magic can be fun, as long as it doesn't break anything important."

"If you say so."