ACCIDENTS BY RAIL AND SEA. 187 



made with discrimination. The first test often shows blue to be a " color 

 of confusion." This may, in certain cases, be the sign of violet-blind- 

 ness, but not always. We have not thought it advisable to admit defects 

 of this kind ; only the most marked cases, that other examinations 

 establish as violet color-blindness, should be reckoned in the statistics. 

 Finally, to acquire a desirable uniformity, it is necessary to add that in 

 the preparatory examination, it is my habit to indicate in the journal, 

 especially kept for that purpose, cases of complete color-hlindness by 2 

 (2 E., 2 G., 2 v.), those of incomplete blindness by 1, and those of feeble 

 chromatic sense by 0.5 (0.5 R., 0.5 G., 0.5 V.). 



4. — PRACTICAL RULES AND SPECIAL DIRECTIONS FOR THE CONDUCT 



OF THE TRIAL. 



The method, as we have said, plays an important part in an examina- 

 tion of this kind, not only from the principles upon which it rests, but also 

 from tbe manner in which it is used. The best plan for directing how 

 to proceed is by oral instructions and de visu; but here we are obliged 

 to accomplish this by description. Now, this is always defective in some 

 respects, especially if we wish to be brief. What has been said would 

 evidently sufiBce for an intelligent and experienced physician, but it 

 may not be superfluous to enter still further into detail to provide against 

 any possible difficulties and loss of time. The object of the examination 

 is to discover the nature of a person's chromatic sense. Now, as the 

 fate of the one to be examined and that of others depend upon the 

 correctness of the judgment pronounced by the examiner, and that this 

 judgment should be based upon the manner in which the one examined 

 stands the trial, it is of importance that this trial should be truly what it 

 ought to be, a trial of the nature of the chromatic sense and nothing 

 else, an end that will be gained if our directions are strictly followed. It 

 is not only necessary that the examiner carefully observe them — which 

 does not seem to us difficult — but that he also take care that the indi- 

 vidual examined does thoroughly what is required of him. This is not 

 always as easy as one might suppose. If it were only required to ex- 

 amine intelligent people, familiar with practical occupations and espe- 

 cially with colors, and with no other interest connected with the issue of 

 the examination than to know whether they are color-blind or not, the ex- 

 amination would be uniform and mechanical. But it is required to ex- 

 amine people of various degrees of culture, all of whom, besides, have a 

 personal interest in the issue of the examination. Different people act 

 very differently during the examination for many reasons. Some submit 

 to it without the least suspicion of their defect; others are convinced that 

 they possess a normal sense. A few only have a consciousness or at least 

 some suspicion of their defect. These last can often be recognized before 

 the least examination by keeping behind the others, by attentively follow- 

 ing the progress of the trial, but if allowed willingly remaining to the 

 last. Some are quick ; others slow. The former approach unconcernedly 



