LETTERS TO THE EDITORfor investigating possible anisotropy in oriented crystals. The preliminary data agree in order of magnitude with the results deduced by Jones 6 and Blackman 7 from the magnetic susceptibility. experiments. However, their ellipsoidal models do not appear to explain our data. The interpretation of our results for multiple carriers is quite involved, particularly for the magnetic field parallel to the metal surface. 8 The simplest situation occurs for transverse H and circular polarization, 9 which would also permit the distinction between holes and electrons. More complicated cases involving ellipsoidal models are being analyzed. The theory which excludes the phenomenon of anomalous skin effect will have to be further refined.We would like to thank Dr. H. J. Zeiger and Mrs. Laura M. Roth for many helpful suggestions and discussions and Mr. W. M. Walsh, Jr. for assisting with some of the experiments.