  We present our analysis of a system of interacting islands of XY spins on a
triangular lattice that has been introduced a few years ago by Eley et al. to
account for the phenomenology in experiments on tunable arrays of proximity
coupled long superconductor-normal metal-superconductor junctions. The main
features of the model are the separation of a local and a global interaction
energy scale and the mesoscopic character of the spin islands. Upon lowering
the temperature the model undergoes two crossovers corresponding to an
increasing phase coherence on a single island and to the onset of global
coherence across the array; the latter is a thermodynamical phase transition in
the Ising universality class. The dependence of the second transition on the
island edge-to-edge spacing is related to the proximity-effect of the coupling
constant.
