remains the same.After mechanically damaging a sample we also observe a shift of the peak to larger fields. Just as in the irradiation experiments, the temperature dependence shows an increase in the intercept A without a change in B.(8) Other metals. -Experiments in Bi, Ga, and K would seem to fit the Cu story, and we suggest that the effects observed in Refs. 3-5 are due to the same mechanism. We have examined such data to find that Eq. (4) also gives reasonable agreement with observed field values.In conclusion, we would like to acknowledge the many useful discussions we have had with E. A. Kaner, H. J. Fischbeck, A. B. Pippard, and M. Ya. Azbel\ In particular, M. Ya. Azbel' has pointed out to us that the contribution to dZ/dH of surface electrons should diverge as Second-harmonic generation (SHG) has been directly measured in InSb as a function of photon energy for second-harmonic (SH) photon energies near the fundamental band-gap energy. The ex-