The question which relate a slow steady motion of a viscid and electrical conducting fluid, in a moving spherical rigid envelope, which is plunged in a uniform magnetic field, has particular interest for the study of the inner magnetism of the earth. In this first paper the author considers the stationary magnetohydrodinamic equations in the case of small velocity and weak inducted magnetic field, and meanwhile he shows that the vortex vector and the conductive current verify a some differential equation of the fourth order. After the author attends to determine the vortex vector and the conductive current in a point within the sphere when theirs values are however asssigned on the surface.