On the basis of this calculation I find that the old, well-trained motormen come to a result of about 450, and I should consider that an average standard.  This would mean that a man who uses 400 seconds would not be allowed to make more than 5 omissions, in 350 seconds not more than 10, in 300 not more than 15, in 250 not more than 20, under the condition that these are the results of the first set of experiments.  Where there are more than 20 omissions made, mere quickness ought not to be allowed as a substitute.  The man who takes 150 seconds and makes 30 mistakes would come up to the same standard level of 450.  Yet his characteristics would probably not serve the interests of the service.  He would speed up his car and would make better time than any one else, but would be liable to accidents.  I should consider 20 mistakes with a time not longer than 250 as the permissible maximum.  Among the younger motormen whom I examined, the best result was 290, in which 270 seconds were used and only 2 omissions made.  Results below 350 may be considered as very good.  One man, for instance, carried out the experiment in 237 seconds with 11 mistakes, which gives the result 347.  From 350 to 450 may be counted as fair, 450 to 550 as mediocre, and over 550 as very poor.  In the case of old men, who may be expected to adjust themselves less easily to artificial experiments, the limits may be shifted.  If the experiments are made repeatedly, the valuation of the results must be changed accordingly.  The training of the men in literary and mathematical work or in experimentation may be considered, as our experiments have shown that highly educated young people with long training in experimental observations can pass through the test much more quickly than any one of the motormen could.  Among the most advanced graduate students who do research work in my Harvard laboratory there was no one whose result was more than 275, while, as I said, among all the motormen there was no one whose result was less than 290.  The best result reached was by a student who passed through the test in 223 seconds with only 1 mistake, the total therefore being 233.  Next came a student who did it in 215 seconds with 3 mistakes, total, 245; then in 228 seconds with 2 omissions, total, 248, and so on.

I recapitulate:  With men on the educational level and at the age that comes in question for their first appointment in the service of an electric railway company, the test proposed ought to be applied according to this scheme.  If they make more than 20 mistakes, they ought to be excluded; if they make less than 20 mistakes, the number of omissions is to be multiplied by 10 and added to the number of seconds.  If the sum is less than 350, their mental fitness for the avoidance of accidents is very high, between 350 and 450 fair, and more than 550 not acceptable under any conditions.  I submit this, however, with the emphasis on my previous statement that the investigation