We best recognize the significance of these various methods by selecting a few concrete cases as illustrations and analyzing them in detail. But a word of warning may be given beforehand so as to avoid misunderstandings. These examples do not stand here as reports of completed investigations, the results of which ought to be accepted as conclusive parts of the new psychotechnical science; they are not presented as if the results were to be recommended like a well-tested machine for practical purposes. Such really completed investigations do not as yet exist in this field. All that can be offered is modest pioneer work, and just these inquiries into the mental qualities and their relations to the industrial vocations have attracted my attention only very recently, and therefore certainly still demand long continuations of the experiments in every direction. But we may hope for satisfactory results the earlier, the more coöperators are entering the field, and the more such researches are started in other places and in other institutions. I therefore offer these early reports at the first stage of my research merely as stimulations, so as to demonstrate the possibilities. As an illustration of the method of examining the mental process as a whole, I propose to discuss the case of the motormen in the electric railways. As an illustration of the other type, namely, of analyzing the activity and testing the elementary functions, I shall discuss the case of the employees in the telephone service. I select these two functions, as both play a practically important rôle in the technique of modern economic life and as in both occupations very large numbers of individuals are engaged in the work. VIII EXPERIMENTS IN THE INTEREST OF ELECTRIC RAILWAY SERVICE