The abilities of various extensive shower arrays to detect possible departures from isotropy of the directions of incidence of very high-energy cosmic-ray primaries are analyzed. The effects of angular resolution, selectivity of total energy and sensitivity to the nature of the primary are discussed. A simple method of analyzing variation in intensity with declination is given and applied to some recent experimental results. It is shown that in two well-known cases these are not consistent with the hypothesis of isotropy of incoming directions.

• Received 24 March 1958

DOI:https://doi.org/10.1103/PhysRev.116.177