Effect of Galactic Rotation Upon the Intensity of Cosmic Radiation

The paper presents a mathematical theory of dependence of cosmic-ray intensity upon galactic rotation, discussed by A. H. Compton and I. A. Getting. The formulae obtained by Compton and Getting for neutral particles are deduced by processes closely analogous to the processes used by those authors. It is shown, however, that the extension to charged particles may be formulated in a manner which makes use of the modified form of Liouville's dynamical theorem which has been found successful in other cosmic-ray problems, and the result is that the intensity at any point on the earth's surface is expressed in simple manner in terms of the direction of the orbit of the charged particle when traced back to infinity. Attention is called to the modification demanded by the theory of relativity in the intuitive picture of the phenomenon. The simple na\"{}ve picture of what happens visions a stream of charged particles with the earth moving, for example, towards them. In this picture there is the alteration of relative velocity produced by the earth's motion, which is responsible for the change of intensity. The theory of relativity demands, however, a picture in which there is no alteration of relative velocity by the earth's motion, but where there is a change of particle density which conspires to produce a result the equivalent of that produced by change of relative velocity in the simple picture.