144 COLOR-BLINDNESS IN ITS RELATION TO 



that the method of iDSpection conld be used and was expedient for rail- 

 ways. Moreover, it proved that there really were color-blind in almost 

 every grade of service of a Swedish railway, and this without there 

 having been the slightest suspicion of it, which confirmed my opinion of 

 the utility and importance of enabling those employed on railways to 

 conviuce themselves de visu of the nature of color-blindness and of its 

 practical value to railways. 



Relying upon the experience I had just acquired, I wrote, September 

 25, to the royal directors of the state railways, and called attentiou, 

 amongst other matters, to the necessity of establishing a systematic con- 

 trol over the sense of colors amongst railway officials, and requested at the 

 same time permission, in the presence of the directors, or a person desig- 

 nated for the purpose, to examine the officials attached to any railway 

 whatsoever for the purpose of convincing the directors, in a practical 

 manner, of the true nature and importance of the question. At this time 

 the directors had already issued orders that as incapacity to distinguish 

 primitive colors closed the avenue to railway employment, the physi- 

 cians attached to the different lines must examine all applicants, and 

 that heads of sections must afterward examine into whether any of 

 their subordinates were incapable of distinguishing these colors, in the 

 use of flags and ordinary signal-lights, in any way which seemed pro- 

 per to them. On the other hand, however, debates and experiments on 

 color-blind individuals, at the Physiological Institute of Upsal, had 

 enabled me to succeed in interesting in the question several persons at- 

 tached to railways, and amongst them all the directors of the Up.sal- 

 Gefle line. 



In another letter to the royal directory, dated October 8, I invited 

 the members to be present at one of these experiments, to be able to 

 form a better judgment of the question. Two engineers of the rail- 

 way presented themselves October 11, and on the 13th the chief 

 director, Mr. Troilius, came in person. From this day success seemed 

 assured. As early as October 16, the directors ordered that a physician 

 from each district, and as many more as should desire, should assemble 

 at my office at an appointed time, to acquaint themselves with the 

 methods that I would explain to them relative to the examination of 

 cases of color-blindness amongst the railway personnel. In consequence 

 of this, at the appointed time, October 24, twenty-six physicians at- 

 tached to railways assembled in the Amphitheater of Physiology at 

 Upsal, and also thirty-two individuals employed on railways, amongst 

 whom were the heads of nearly all the lines belonging to the private 

 companies of the country. 



November 9, the managers directed the physicians of the lines to 

 proceed gradually, and according to my method, in the examination of 

 all the men then employed on railways. Those of the physicians 

 who did not understand this method, added the circular, should 

 study it, either with me, or with one of the physicians who had been 



