C. Herring Van Vleck while he was preparing this work for publication in 1953 and suggested a consideration, which I subsequently elaborated in my book: the energy cost of actuations might be significantly reduced by screening by the mobile electrons of the s-p band. But it was only with the development of Fermo logy in the 1960s that itinerant magnetism became fully respectable. For example I remember that when I submitted two papers to the Physical Review in 1951 or the subject of the description of Bloch wall states and long wavelength magnons in itinerant models, the referee, although finding nothing wrong with the papers objected that it was wasteful to devote so much space to such an unrealistic subject as the itinerant model of magnetism The benefits of the close interaction between experimentalists and theorists at Bell Laboratories were nowhere better illustrated than in some of the developments having to do with dislocations and plasticity. In the late 1940s, Shockley was very interested in dislocations, and he succeeded in getting an imaginative young applied mathematician, Thornton Read, to join him in thinking about them. They realized early that the rows of etch pits that revealed subgrain boundaries and lineage structure in the routine testing of semiconductor crystals for perfection could be used to test an idea that i believe was originally due to Burgers, namely that small-angle grain boundaries should consist of reasonably well spaced dis locations. They got experimentalists to work at simultaneously measuring grain boundary energies(by the angles of grain boundary grooves), and the spacings of the corresponding dislocation arrays in etched samples cut normally to the grain boundary. They deduced and confirmed a @log 8 dependence of the grain boundary energy on the angle 0 between the grain boundary and a simple rational orientation In another example, some of us working in basic physics happened to hear of the accidental discovery of thin tin whiskers growing out of the plating inside some sealed channel filters that had been used in telephone applications, and that mysteriously developed short circuits, traced ultimately to the whiskers. It occurred to us that because of their small diameter(one or two micrometres)such whiskers might well be perfect crystals free of dislocations, in which case they should be capable of withstanding very large strains without suffering plastic deformation John galt volunteered to do some experiments on the whiskers, and these confirmed the expectations. The subject of plasticity in whiskers eventually developed quite a sizeable literature. A third and especially important development in dislocation physics came in 1950, when, in a remarkable time coincidence, Thornton Read and F. C. Frank simultaneously and independently conceived the concept of dislocation multiplication by regeneration of loops around a pair of pinning points(the Frank Read source) REFERENCeS (1)Brillouin, L. 1933 J, Phys. Radium 4, 1 2)Lowdin, P.-0. 1951 J. chem. Phys. 19, 1579