A jell~um/~rce-elcctron model is used lo estimale the static elatric field at the surface of a mctol cluster_ The electric field near a cluster with a radius of lo-50 au is round to deviate signifrcnntly From the field at the snme distance from an infinite metallic plane This will Influence several adsorbate properlies. including bondrng. At a smooth planar surlace the field is suffinently strong IO cause signilicant contributions to the &pole and transition momenk of an admolaule. These contributions become even more important at the surrace ol a cluster. It is postulated that microscopic roughness may enhance the electron-transfer contribution to surface-enhanced Raman scattering. smce the Fenm energy of electrons in a protuberance is mcreascd relative to the bulk Moreover, for the same reason. the molecule-metal interaction is mcreased when the molerule IS adsorbed at a protuberance Finally. by means of a WKB formula derived rrom the model. an accwa~c prediction can bc made of the "magic numbers" whxh reler to the enhanced abundanw or cenan clusw-s when formed in an alornic beam Thererore these numbers are bkcly to be determined by the symmetry of the problem and not by the detailed nature of the one-electron polential.