  We study the eigenvalues of the Dirichlet-to-Neumann operator on a finite
subgraph of the integer lattice Zn. We estimate the first n+1 eigenvalues using
the number of vertices of the subgraph. As a corollary, we prove that the first
non-trivial eigenvalue of the Dirichlet-to-Neumann operator tends to zero as
the number of vertices of the subgraph tends to infinity.
