or that in just such instants a feeling of repose and security came over them and that with sure instinct they turned in the direction which they would have chosen after mature thought.  The results of the experiments in sorting the cards confirmed this self-observation in such frequent cases that it may indeed be hoped that a more extended test of this method will prove its practical usefulness.  It is clear that the field is a wide one, as these different types of mental dispositions must be of consequence not only in the ship service, but also to a certain degree in the railroad service and in many other industrial tasks.

We have emphasized from the start that as a matter of course such a tested function, while it is taken in its complex unity, is nevertheless not the only psychophysical disposition of significance.  This is as true for the ship officer as it was for the motorman of the electric car.  If we were to study all the mental dispositions necessary or desirable for the ship officer, we should find many other qualities which are accessible to the psychological investigation.  The captain of the ship, for instance, is expected to recognize the direction of a vessel passing in the fog by the signals of the foghorn.  But so far no one has given any attention to the psychological conditions of localization of sound, which were for a long while a much-studied problem of our psychological laboratories.  We know how this localization is dependent upon the comparison of the two ears and what particular mistakes occur from the different sensibility of the two ears.  Yet there are to-day men on the bridges of the ships who hear much better with one ear than with the other, but who still naively believe that, as they hear everything very distinctly with one ear, this normal ear is also sufficient for recognizing the direction of the sound.  It is the same mistake which we frequently see among laborers whose vision has become defective in one of their eyes, or one of whose eyes is temporarily bandaged.  They are convinced that the one good eye is sufficient for their industrial task, because they are able to recognize everything clearly and distinctly.  They do not know that both the eyes together are necessary in order to produce that psychological combination by which the visual impression is projected into the right distance, and that in the factory they are always in danger of underestimating the distance of a wheel or some other part of the machine and of letting the hand slip between the wheels or knives.  The results of experimental psychology will have to be introduced systematically into the study of the fitness of the personality from the lowest to the highest technical activity and from the simplest sensory function to the most complex mental achievement.

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EXPERIMENTS IN THE INTEREST OF TELEPHONE SERVICE