Hello Russell.

> I understood, perhaps naively, that perpetual motion devices were
> officially unpatentable.

  Sez who I wonder?

  It depends on whether there is a general principle in patenting that
the concept must actually *work*.  If so, then PMDs would be excluded,
but that would presume a duty on the part of the Patent Office to
actually evaluate the feasibility of every patent, employing engineers
(expensive) to do so.

  I was under the impression that was *not* the Patent Office's r™le and
thus no official stand on PMDs.
-- 
  Cheers,
        Paul B.