  The Poisson's ratio of a spring network system has been shown to depend not
only on the geometry but also on the relative strength of angle-bending forces
in comparison to the bond-compression forces in the system. Here we derive the
very simple analytic result that in systems where the spring interaction
strength is equal to the bond-reorientation interaction, the Poisson's ratio
identically goes to zero and is independent of the network geometry.
