Development of Atmospheric Cosmic-Ray Showers

In a recent paper Thornton and Clay strongly suggest a very early development in the atmosphere for small cosmic-ray showers and consequently require a change in primary mass composition in the energy range ${10}^{15}$-${10}^{17}$ eV. It is suggested here that when allowance is made for inconsistencies in the data the necessity for the early development of small showers-and hence the inferred rapid change in primary composition-is removed.