Space Forum / Space Flight / September 2003

O'Neill hosted a "space colonization" conference at Princeton
University in 1974 and again in 1975.  Along with other proponents
of the concept, he founded the Space Studies Institute (SSI), which
has continued to host a biennial series of "space manufacturing"
conferences at Princeton since 1977.

He also directed three NASA Summer Studies on Space Colonization,
in 1975, 1976, and 1977.  The most famous of these is the 1975
Summer Study, hosted by Stanford University and NASA Ames Research
Center.  It produced a colony design known as the "Stanford Torus".
That study concluded that a torus was the most efficient enclosure
for a population of 10,000 living in 1 g at 1 RPM.

By being a little less conservative on the rotation rate, allowing
up to 2 RPM, the study found that a sphere was more efficient.
(Smaller radius, more compact.)  They named the prototype spherical
colony the "Bernal Sphere", in honor of J. D. Bernal.

(Although, Bernal was not a proponent of Earth-like colonies with
artificial gravity.  Instead, he advocated a "three-dimensional,
gravitationless way of living".  Gradually, during a "larval,
unspecialized existence" lasting sixty to one hundred twenty years,
inadequate body parts would be replaced, and new sensory and motor
mechanisms would be grafted on.  Finally, a person "would emerge as
a completely effective, mentally-directed mechanism, and set about
the tasks appropriate to his new capacities."  But I digress ...)

The bigger cylinders are extensions of the sphere, spreading the
end caps apart and increasing the radius.

The Summer Studies discuss the design evolution in considerable
detail, and the SSI Proceedings include contributions from lots of
other folks on various aspects of space colonies and space
manufacturing facilities.

The 1975 Summer Study is on the web, as are the SSI Proceedings
Tables of Contents:

  O'Neill, Gerard K. (1974).  "The Colonization of Space."  _Physics
     Today_, vol. 27, no. 9, p. 32-40, September 1974.  American
     Institute of Physics.

  Johnson, Richard D.; Holbrow, Charles (eds.) (1977).  _Space
     Settlements: A Design Study_ (NASA SP 413).  NASA Scientific
     and Technical Information Office.  Authored by the
     participants of the 1975 Summer Faculty Fellowship Program in
     Engineering Systems Design at Stanford University and NASA
     Ames Research Center.

     http://lifesci3.arc.nasa.gov/SpaceSettlement/75SummerStudy/s.s.doc.html
     http://lifesci3.arc.nasa.gov/SpaceSettlement/75SummerStudy/Design.html
     http://lifesci3.arc.nasa.gov/SpaceSettlement/75SummerStudy/Table_of_Contents1.html

  O'Neill, Gerard K.; O'Leary, Brian (eds.) (1977).  _Space-Based
     Manufacturing from Nonterrestrial Materials_ (Volume 57,
     Progress in Astronautics and Aeronautics).  American Institute
     of Aeronautics and Astronautics.  Technical papers derived from
     the 1976 Summer Study at NASA Ames Research Center.

  Billingham, John; Gilbreath, William (eds.) (1979).  _Space
     Resources and Space Settlements_ (NASA SP 428).  NASA Scientific
     and Technical Information Branch.  Technical papers derived from
     the 1977 Summer Study at NASA Ames Research Center.

  Space Studies Institute
     http://www.ssi.org/
     http://www.ssi.org/conference_report_contents.html
     http://www.ssi.org/catalog.html

There must have been a least a few engineering drawings.  I remember for a
while SSI's newsletter went out in an envelope which had a diagram of a Bernal
Sphere on it.

Sorry I don't have better information.  You may already be aware of the
existence of these websites, but just in case:

http://members.aol.com/oscarcombs/settle.htm
http://lifesci3.arc.nasa.gov/SpaceSettlement/