Pairs and tripletes of galaxy clusters

A list is given, containing 68 pairs and 21 triplets of clusters of galaxies, obtained by a computer analysis of Abell's catalogue. The ratio of distance between members of a system to the distance from the neighbouring cluster has been taken as a criterion of isolateness of a system. The expected fraction of chance (optical) systems in the list is about 1/4. The indices which show the connection between clusters of galaxies in multiple systems are noted. The positive correlation of visible values of the brightest galaxy clusters takes place. The average dimension of galaxy cluster pairs within errors is equal 4.8 Mpc at the Halle