One of the purposes of a scientific paper is to provoke thought and discussion and Dr. Rosaire's paper has admirably performed these purposes. Moreover, he offers a plausible explanation for some effects which have been found with the electrical transient method—an explanation which does not do violence to the knowledge of and experience with previously existing electrical current methods. How it was possible to pick up the effects of deeply buried structure and faults with such current and potential spreads as are used in transient work was a most difficult question to answer and the feat, if possible, amounted almost to legerdemain. By bringing the effect of deeply buried structure much nearer the surface with his zone of mineralization Dr. Rosaire has clarified the problem greatly. Even so there may be some skeptics who will wonder whether it is possible, after taking into account the effects of surface and near surface conductivity changes which most certainly will profoundly alter the form of the electrical transient to interpret in terms of geological structure any residual effect which may be due to somewhat deeper physical changes.