Previous investigations on the confinement of a plasma in the magnetic field from one or several ring-shaped magnetic coils are extended in this paper. The energy losses are analysed for a number of magnetically screened leads which support the coils situated inside the plasma volume. Under thermonuclear conditions it is found that the losses due to the leads become negligible compared to the thermonuclear power of the DD and DT reactions when the main magnetic field is purely poloidal. In a sheared field the same losses are larger, but still negligible for the DT reaction, and it should in any case be possible to make them less than the thermonuclear power of the DD reaction. In connexion with the present type of configuration some further comments are made on the problems of stability, plasma generation and heating, the experimental analysis of the confinement, and on some of the engineering problems.