The distribution of Abell clusters of galaxies is analysed to study the
regularity of the supercluster-void network. A new geometric method sensitive
to the regularity of the location of clusters is applied. We find that the
supercluster-void network resembles a cubical lattice over the whole space
investigated. The distribution of rich superclusters is not isotropic: along
the main axis of the network it is periodic with a step of length about 130 Mpc
(for Hubble constant h=1), whereas along the diagonal of the network the period
is larger. This large-scale inhomogeneity is compatible with recent CMB data.Comment: 7 pages LaTeX text (sty files added), 4 PostScript Figures, submitted
to Astronomy and Astrophysic