The results of observations, made during 1959–64, on intensity variations of EAS of mean sizes 1.4 × 104 to 1.4 × 105 particles at sea level are reported. Variations of shower size caused by fluctuations in pion decay have been observed and these correlate with density variations in the atmosphere. The corrected sidereal rate shows no evidence for anisotropy of the arrival directions of showers.