  The transformation of the $SL(2,R)/U(1)$ black hole under a boost of the
subgroup U(1) is studied. It is found that the tachyon vertex operators of the
black hole go into those of the $c=1$ conformal field theory coupled to
gravity. The discrete states of the black hole also tend to the discrete states
of the 2-d gravity theory. The fate of the extra discrete states of the black
hole under boost are discussed.
