  The first massive level of closed bosonic string theory is studied.
Free-field equations are derived by imposing Weyl invariance on the world
sheet. A two-parameter solution to the equation of motion and constraints is
found in two dimensions with a flat linear-dilaton background. One-to-one
tachyon scattering is studied in this background. The results support Dhar,
Mandal and Wadia's proposal that 2D critical string theory corresponds to the
c=1 matrix model in which both sides of the Fermi sea are excited.
