A note in the last FML reminded on something that may help folks in the less
oppressive areas up north.  We only use AC for the four or five weeks in mid
July to mid August.  Aside from that I found that the ferrets did well with
a slab of slate in the bottom of the cage.  What I got was a piece of the
flat colored paving slate 1" thick and about 12" x 30".  (Actually I pulled
up a piece from the edge of the walkway round the pool and washed it off.)
Because it conducts heat better than things like wood it always feels cool.
I put it in the bottom of the cage and periodically one or other of them
would go and do a "speed bump" on it.  It certainly isn't going to work when
the room gets into the 90s but they seem to like it when its only moderately
warm.  If you have a bit lying around your yard try it, its certainly cheap,
clean, and its doesn't wear out :)
[Posted in FML issue 1631]