Abstract
Since 19.48, three reports have been read by the author at the meetings of the Physico-Mathematical Society of Japan about a special after effect, name y a delayed electron emission which is shown by the metal surface bombarded by electrons The present paper is the summarized report mentioned above. In Part I, the qualitative results of the preliminary research are described: the discovery of the phenomenon, confirmation of exciter of the phenomenon, and investigation on the nature of emitters. In Part II, the quantitative investigations are mentioned: characteristics of this phenomenon, influence of the condition of the surface, relation between the after effect and the secondary electron emission phenomena. In Part III, the discussions and concusions are given According to the results of the research, this phenomenon is closely related to the secondary electron emission and the explanation was given by the author that the effect was caused by a kind of the cold emission which was excited by the positive charge produced by secondary emission. This effect is observed on the surface of nearly all kinds of metal and is never restricted to special material and composited surface
