The influence of galactic rotation according to Com p ton and Get tin g .is discussed for rays in a vertical system of counters at the earth's magnetic equator. For an exponential energy distribution according to C I a y: e-I '! (3 x JOl') the diurnal effect is found to be at least 0.25%.
Com p ton and Get tin g 1) have considered the influence of galactic rotation on the intensity of cosmic rays on the following principle: Due to the motion of the earth with a velocity of 300 km/sec = ~c towards d;e point of right ascension o: = 20 h 40'" and declination a= 47ยฐ, the "forward" part of the earth receives more particles than the "backward" part, so that in the course of 24 hours a periodic effect is to be expected, assuming that the radiation is isotropic in a non-moving system (c = velocity of light). Also the change of energy due to the motion has its influence, whereas the bending of the cosmic rays in the earth's magnetic field introduces a complication. Data by He s sand S t e i n m au r e r 2) show a sidereal variation of the kind expected, though not yet establishing the effect beyond any doubt.
It appears that a quantitative treatment can be best carried out for a case where both the experimental conditions and the influence of the earth's magnetic field arc as simple as possible..Such a case is that of a vertical system of counters at the earth's magnetic equator, considered in a previous paper written in collaboration with H. Zan s t r a 3), which will be referred to as paper I *).
One of the results of this investigation is the following: Given an *) Erratum. On p"77 of this paper read ..equator" in stead of ..meridian".