Experimental and Theoretical Evaluation of the Density Spectrum of Extensive Cosmic-Ray Showers

Measurements are made of the density spectrum of extensive cosmic-ray showers at an altitude of 120 m above sea level. The results together with the measurements previously made at 2200 m confirm the electronic nature of the primary radiation which produces the extensive showers. It is estimated that the denser showers are generated by electrons of ${10}^{15}$ to ${10}^{16}$ ev, the less dense showers by electrons of energies ${10}^{12}$ ev.