1. Egedal, J., , Zs. Geophysik, 6, 157-158 1930,
2. Rooney, W. J., , Terr. Mag., 37, 363-374 1932,
3. Gish, O. H., , Sci. Mon., 32, 5-21 1931,
4. It should be remembered that for coastal regions irregular variations of the earth-currents have been observed (see Mathias, E., , : Traité é1ectricité atmosphérique et tellurique, , 468– -469 , Paris, 1924, ).
5. Climatic cycles;Brunt;Geog. J.,1937