抄録
The magneto-hydrodynamic theories of the earth's main magnetic field rest on the process of simple induction. Since emagn>>emech, this is only possible, if the stronger magnetic field become force-free or pressure-compensated. It is supposed, that the period of≈50 years, that is to be find in the secular variations of the magnetic field vector, in the amplitudes of the Chandler-Wobble and in the lenght of a day are caused by a magneto-hydrodynamic oscillation. The origin of the dipolefield of the earth is to be find in the boundary-layer of the core.
