Longitudinal Distribution of Čerenkov Light from Extensive Air Showers

Measurements of the longitudinal distribution of the Čerenkov light associated with extensive cosmic-ray air showers of approximately ${10}^{15}$-ev minimum energy are presented. These measurements are compared (1) with those of Bassi et al. resulting from their analysis of the electron component of extensive air showers and (2) with the distribution calculated by Monte Carlo techniques from Coulomb scattering of the shower electrons.