The test of the method lies first in the fact that the tried motormen agreed that they really pass through the experiment with the feeling which they have on their car.  The necessity of looking out in both directions, right and left, for possible obstacles, of distinguishing those which move toward the track from the many which move along the track, the quick discrimination among the various rates of rapidity, the steady forward movement of the observation point, the constant temptation to give attention to those which are still too far away or to those which are so near that they will cross the track before the approach of the car, in short, the whole complex situation with its demands on attention, imagination, and quick adjustment, soon brings them into an attitude which they themselves feel as identical with that in practical life.  On the other hand, the results show a far-reaching correspondence between efficiency in the experiment and efficiency in the actual service.  With a relatively small number of experiments this correspondence cannot be expected to be complete, the more as a large number of secondary features must enter which interfere with an exact correlation between experiment and standing in the railway company.  We must consider, for instance, that those men whom the company naturally selects as models are men who have had twenty to thirty years of service without accidents, but consequently they are rather old men, who no longer have the elasticity of youth and are naturally less able to think themselves into an artificial situation like that of such an experiment, and who have been for a long time removed from contact with book work.  It is therefore not surprising, but only to be expected, that such older, model men, while doing fair work in the test, are yet not seldom far surpassed by bright, quick, young motormen who are twenty years younger, even though they are not yet ideal motormen.  Moreover, the standing in the company often depends upon features which have nothing to do with the mental make-up of the man, while the experiment has to be confined to these mental conditions which favor accidents.  It is quite possible that a man may happen to experience a slight collision, even though no conditions for the accident were lying in his mental make-up.  But we may go still further.  The experiment refers to those sides of his mind which make him able to foresee the danger points, and that is decidedly the most essential factor and the one from which most can be hoped for the safety of the public.  But this does not exclude the possibility that some other mental traits may become causes of accidents.  The man may be too daring and may like to run risks, or he may still need discipline, or he may not be sufficiently acquainted with the local conditions.  Any such secondary factors may cause some slight accidents with the man who shows rather fair results in the experimental test of his foresight.  Finally, we must not forget that some men enter into such tests