  The gravitational interactions of the four-dimensional effective theory
describing a general $N$-brane model in five dimensions without radion
stabilization are analyzed. Both uncompactified and orbifolded models are
considered. The parameter space is constrained by requiring that there be no
ghost modes in the theory, and that the Eddington parameterized post-Newtonian
parameter $\gamma$ be consistent with observations. We show that we must reside
on the brane on which the warp factor is maximized. The resultant theory
contains $N-1$ radion modes in a nonlinear sigma model, with the target space
being a subset of hyperbolic space. Imposing observational constraints on the
relative strengths of gravitational interactions of dark and visible matter
shows that at least 99.8% of the dark matter must live on our brane in this
model.
