While they were sitting in the back of the mail cart, they had maps to study, of each of the cities that they'd be passing through. They would have to do some short local deliveries in each, while the horses were being changed.
They also had some more of the scroggin stuff to snack on, or trail mix, as the American member of their group called it.
They were given relatively safe neighbourhoods to deliver in at each city, although obviously they still had to split their group. They soon decided to make a competition of it, with the local postmaster being the judge at each city.
As they got closer to the Rim, some of the cities, and even some of the smaller towns and villages, started to look better built, not so much built just for war. The architecture spoke of both good defence and a strong mercantile and academic presence, as if military was still something to be considered, but wasn't the most important thing.
When they reached a Rim Kingdom Capital, they decided to stay a few extra days to see if they could learn any more.
They were given some similar information to what they had as already learned, but gained some new information as well. For example they learnt more about the rumour they'd heard about cracks moving.
“Not all crack borders move. And of those that do, not all of them move on both sides.”
Their puzzled looks implied that further explanation was required.
“In your world and this world. A border might always be at the same place in your world, but never in the same place in this world. Or vice versa. You might be able to find the same place again from here, but it takes you to a completely different part of your world.”
They also learnt a bit more about Mount Earth in general.
“Working together with the Postal Guild, we managed to discover the circumference of Mount Earth. The useful thing about Seven League Boots, from an academic perspective, is that when active, they always step exactly seven leagues.
It turned out to be thirty nine thousand, four hundred and ten leagues. Your world, the cracks and the rim.”
“Also, we calculated, with some estimation, that the height is about eight thousand leagues. Although some of our estimates must have been off, because we have learned from our surroundland counterparts that it is notably more than that.”
They also noticed some landscape artworks that were presumably of various parts of The Rim. Seemingly bottomless cliffs, and sea sized waterfalls that looked like they fell into nothing.