  Some recent results on the applications of duality (and related)
transformations to general four-dimensional, spherically symmetric,
asymptotically flat and time-independent string configurations are summarized.
Two classes of results have been obtained. First, these transformations are
used to generate the general such solution to the lowest-order field equations
in the alpha' expansion. Second, the action and implications of duality (based
on time-translation) on the general configuration is determined. It is found to
interchange two pairs of the six parameters which label these configurations,
namely: (1) the mass with the dilaton charge, and (2) the axion charge with the
Taub-NUT parameter. For the special case of the Schwarzshild black hole this
implies the relation M -> - k/M, where k is a known, positive, quantity. It is
argued that, in some circumstances, dual theories need not be equivalent in the
simplest sense.
