Using Bhabha's method, the intensity of slow mesons is determined. The intensity of mesons of energy greater than ${10}^8$ ev and less than 2.7 × ${10}^8$ ev is 6 percent of the total meson intensity. Near the geomagnetic equator, the total intensity increases by 54.4 percent, the meson intensity by 21.7 percent, and the electron intensity by 162.1 percent when the altitude increases from 3100 ft. to 7200 ft. The electron intensity, which is about 25 percent of the meson intensity at 3100 ft., increases to 50 percent of the meson intensity at 7200 ft.

• Received 2 June 1944

DOI:https://doi.org/10.1103/PhysRev.66.183