BARTOL RESEARCH
Notwithstanding more than twenty years *OUNDATION of experimental investigation of the cosmic co~,i~,tion No. ss. radiation, seven of which have been years of intensive activity, we are still wondering where these rays come from, how they are produced and, in fact, whether they consist principally of waves or of corpuscles. In view of the remarkable development in knowledge of the structure of the atom which arose out of the spectroscopic determination of the energies of the characteristic radiations, it is natural that we should look again to energy determinations as the most promising key to the solution of the present mystery. Energy, in one form or another, is a quantity which we feel must be conserved and if it appears in the form of the cosmic radiation equal amount must have been given off during some kind of a quantum transition. The possibility of interpreting the cosmic radiation in terms of quantum transitions was first realized in I928 through the highly interesting speculations of Millikan and Cameron which were based upon their measurements of the absorption of the rays.
If the atmosphere were compressed to the density of water its depth would be approximately ten meters. By carrying their instruments up in airplanes and on mountain tops and by sinking them down in lakes they succeeded in observing the intensity over a range of depths extending from about six meters to eighty meters below the top of the atmosphere. The resulting intensity-depth curve had the general appearance of an exponential, but it was found to deviate from the simple form of this law even when all-sided incidence of the radiation at the top of the atmosphere was taken into account. They did find, however, that the curve could be analyzed as ~67