The Lateral Structure of Cosmic-Ray Air Showers

The lateral distributions of the electrons and penetrating particles in extensive cosmic-ray air showers have been measured directly, and as a function of the size of the showers. No evidence was found for multiple cores in the showers. The lateral distribution of the electrons was found to agree well with that calculated by Moli\`ere, taking into account only Coulomb scattering of the electrons. The density of penetrating particles at a given distance from the core was found to be proportional to that of the electrons. The ratio of p.p. to electrons seems to increase slowly with distance from the core, but changes only by a factor of about 2 between 5 and 100 m from the core, while the electron density decreases by a factor of about 100.Evidence was obtained that most of the penetrating particles reached the apparatus as single, independent particles from the air, but that about \textonequarter{} of the events in which p.p. were detected involved groups of particles that were probably locally produced in the lead.