  We study the response of a two-dimensional hexagonal packing of rigid,
frictionless spherical grains due to a vertically downward point force on a
single grain at the top layer. We use a statistical approach, where each
configuration of the contact forces is equally likely. We find that the
response is double-peaked, independantly of the details of boundary conditions.
The two peaks lie precisely on the downward lattice directions emanating from
the point of application of the force. We examine the influence of the
confining pressure applied to the packing.
