The crust of the earth is discussed as a possible seat of the magnetization of the earth. It is shown that the temperature and pressure to which the crust (a thickness of about 20 km) of the earth is subjected, will make its magnetic mineral contents (e.g., magnetite) highly permeable. The shell can thus be magnetically saturated by a field of very low intensity of the order of 0.01 gauss. It is suggested that the magnetizing field is provided by the “ring current” formed in the space round the earth, during worldwide magnetic storms, as a result of the encounter of the solar neutral corpuscular beams (consisting of an equal number of positive and negative charges) with the earth-magnet. It is shown that an initially existing field of even one-hundredth of the present field is enough to build up the magnetization of the crust to saturation. An explanation of the secular variation is also suggested as caused by the ring current trying to follow (with a lag) the wobbling motion of the magnetic axis round the geographical axis due to the diurnal rotation of the earth. © 1956, All rights reserved.