  Several stationary solutions of the low energy string equations are dualized
with respect to their timelike symmetry. Many of the duals have simple physical
interpretations. Those of the nonextremal three dimensional black hole and
black string are negative mass black strings. The extremal cases of these, and
extremal higher dimensional black strings also, give negative energy plane
fronted waves. In fact, all of the duals of positive mass solutions that will
be considered here have nonpositive energies, but an argument is given which
suggests that this is not true in general.
