How Earthlike?

andy-nimmo wrote:
> How do you build tall buildings on the 6 - 10 metre thick inner
surface of a habitat? I would think O'Neill's preference for small
buildings was a simple matter of constructional capability.

I don't know; A lot of O'Neill's (more accurately Davis's?) work
seemed to depict the idyllic setting.
Are we talking of skyscrapers? They may not have thought of these
because there's no need for single massive buildings.
For structural considerations, they would have to be planned into
the colony design: Counterbalanced, with extra tensioning cables in
the sub-floors or hull.
Anything which needed such concentration of subdivided yet close
proximity spaces would probably be in sub-decks under the habitat
floor, unless you really wanted big buildings for some reason.
Another possibility is the endcaps (If you're thinking of the
island 3, but we seem to have agreed to use a more inherently stable
geometry).
For the Stanford Torus, a cluster of "City" at every other spoke
gives 3 cities, with the other spokes coming down in more rural
settings. Anything too big in a torus is part of the roof support
structure. (I think Heppenheimer's book specified that the spokes
would be the skyscrapers in the habitat) Also, anything too big has
to be balanced.*

It all depends on the population density at the floor level. If we're
packing them into an early habitat, then maybe the entire torus is
built up like an arcology, with only some relatively small open
volumes for relief. Later, after the space cadets can afford the
extravagance, it'll be like the image of the forested open torus, as
was depicted in O'Neill's book.
The population density at 10,000 may be an average mean. A habitat
for an early company city (consider the Panama Canal Zone through
most of its history for an example of this), might hold 20,000 or
more. The later, independantly wealthy retirement village or wildlife
refuge might only have 5,000 or less.

* For another view of an administration/colony services volume, think
about this for a Bernal sphere; 2 or 3 hills in the open inner
habitat volume are hollow, with the admin center built into them.
Sunllight can be piped in from outside with fiber optics/ light
conduits, so it can have real sunlight at any time in any room
regardless of day/night cycles for the habitat. We may or may not
want to go high enough for radically diferent gravity at the top.
I can see all the traffic jams of ultralights & bicycles from all
the commuters coming to the hill city from thier homes in the plains
suburbs.