The medal has on occasion been awarded to more than one person at once ; in 1938 it was won by John Cockcroft and Ernest Walton `` for their discovery that nuclei could be disintegrated by artificially produced bombarding particles '' , in 1981 by Peter Higgs , Thomas Walter and Tom W. B. Kibble `` for their international contributions about the spontaneous breaking of fundamental symmetries in elementary-particle theory '' , in 1982 by Drummond Matthews and Frederick Vine `` for their elucidation of the magnetic properties of the ocean floors which subsequently led to the plate tectonic hypothesis '' and in 1988 by Archibald Howie and M.J. Whelan `` for their contributions to the theory of electron diffraction and microscopy , and its application to the study of lattice defects in crystals '' . The medal has on occasion been awarded to multiple people at a time ; in 1938 it was won by John Cockcroft and Ernest Walton `` for their discovery that nuclei could be disintegrated by artificially produced bombarding particles '' , in 1981 by Peter Higgs and Tom Kibble `` for their international contributions about the spontaneous breaking of fundamental symmetries in elementary-particle theory '' , in 1982 by Drummond Matthews and Frederick Vine `` for their elucidation of the magnetic properties of the ocean floors which subsequently led to the plate tectonic hypothesis '' and in 1988 by Archibald Howie and M.J. Whelan `` for their contributions to the theory of electron diffraction and microscopy , and its application to the study of lattice defects in crystals '' .