  A non-supersymmetric ten-dimensional open string theory is constructed as an
orbifold of type I string theory, and as an orientifold of the bosonic type B
theory. It is purely bosonic, and cancellation of massless tadpoles requires
the gauge group to be SO(32)xSO(32). The spectrum of the theory contains a
closed string tachyon, and open string tachyons in the (32,32) multiplet. The
D-branes of this theory are analyzed, and it is found that the massless
excitations of one of the 1-branes coincide with the world-sheet degrees of
freedom of the D=26 bosonic string theory compactified on the SO(32) lattice.
This suggests that the two theories are related by S-duality.
