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ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 8 



ships, all these have been used to find out how the intensity of cosmic 

 radiation varies with the latitude and longitude and the height of the 

 place of observation. This aspect of the study of cosmic rays can be 



called the geophysical aspect and is, in fact, closely related to the 

 study of the variation of the earth's magnetic field over the surface of 

 the earth. In figure 2 are shown the lines of equal cosmic ray inten- 

 sity — or isocosmic lines, as they are called — and these lines run very 



