Abstract
As examples of non-ellipsoidal samples having reversible magnetic behaviour lead bars of rhomboidal cross section are studied at 4.2K. The magnetic reversibility is associated with the absence of the irreversible migration of flux tubes. The shapes of the samples used allow a calculation of the magnetisation curve which takes into account the macroscopic properties of the intermediate state, with the aid of a simple two-dimensional model. The calculated magnetisation curves are in good agreement with the experimental curves extrapolated for infinite bar lengths.