In recent years several improvements have been made in the manufacturing of resistive, superconducting and hybrid mag nets. Condensed matter physicists are nowadays doing ex periments in steady magnetic fields of up to 30 Tesla. But the field homogenity {/B}, required in a volume of the order of a 3 few cm is usually several orders of magnitude less severe than the one which is needed for high resolution NMR. Over the last 30 years, with each generation of new high resolution NMR spectrometers, from 100 MHz up to 600 MHz, taking advan tage of the increase in sensitivity and resolution, new...