Apparent Clustering of Galaxies

A CONSIDERABLE amount of material on the distribution of external galaxies has become available through the publication of the Harvard and Mount Wilson surveys. Shapley and Hubble have both discussed the observed irregularities in the distribution of these galaxies. Shapley emphasises the non-uniformity of the distribution of matter in the metagalaxy. Hubble finds that ``statistically uniform distribution of nebulæ appears to be a general characteristic of the observable region as a whole'', and hesitates to admit the reality of clusters or groups of galaxies with the exception of the few that are readily recognised as such. Statistical analysis of the available material is now possible; and as the comparison between the observed distribution curves, corrected for the effect of dispersion in the limiting magnitudes, and the theoretical frequency curves, computed on the assumption of random distribution, has yielded some rather definite results, it seems worth while to communicate them in advance of publication in more detail.