  We obtain cosmological four dimensional solutions of the low energy effective
string theory by reducing a five dimensional black hole, and black hole--de
Sitter solution of the Einstein gravity down to four dimensions. The appearance
of a cosmological constant in the five dimensional Einstein--Hilbert action
produces a special dilaton potential in the four dimensional effective string
action. Cosmological scenarios implemented by our solutions are discussed.
(Talk presented at: ``27th Symposium on the Theory of Elementary Particles''
Wendisch--Rietz, September 7--11, 1993)
