Re: comparative size of spheres and flow rivers

Hmm. Rivers being smaller than crystal spheres doesn't _have_ to mean there
are no long rivers -- It could be that the phlogiston, when it hits the
sphere, starts to flow around it. This would make it easier to find a river
once outside a sphere, especially if the rivers are mostly all on the same
plane -- Exit the sphere on that plane and you'll be in a flow of phlogiston
around the sphere -- move at flow speed and you'll hit a river in no time!
Of course, it could still be hard to make sure it's the _right_ river.

This is, of course, not canon and just one possibility that came to my mind
while reading the previous posts.

I think it's not a bad comprimise, though -- Otherwise, you would have to
enter a sphere, travel all the way through it, and exit the other side,
increasing travel times immensely. This may be exactly what you want for
your campaign, of course.

As for other objects in the phlogiston, I don't see any reason why someone
couldn't sail a ship _out_ of one of the rivers into the unflowing
phlogiston. With the help of magic, you could get an unlimited air supply
and begin building a permanent structure. This could be something like a
waystation (or great pirate waiting spot) just outside a popular river, or
it could be a good place to hide a secret base, since the size of the
phlogiston pretty much makes it impossible to accidentally run into it --
You would need some sort of landmarks or magical locator spells to let the
people who are supposed to find it find it, though. Also this would be a
great hiding place for people who have pissed off the deities or other
planar powers, since it's so difficult to open a portal in the Phlogiston.
(Yes, with a limited wish, you can get out or let people in -- But good
luck, even with a wish, opening a portal from another plane to the right
spot in the phlogiston!)

This is basically the same as, in a space opera setting, building a secret
base in deepspace outside of the normal hyperspace routes.