434 ^^^ POPULAR SCIENCE MONTHLY. 



eral Manager, Mr. Pugh, as its chairman, to whose keen interest much 

 of its success is now due. 



The magnitude of the task then began to appear, when the forty 

 or fifty thousand employes of five thousand miles of track, with their 

 ten or twelve thousand men actually dependent upon signals of color 

 for their guidance, of whom four per cent might be color-blind, and 

 ten per cent so defective in visual power, for form and hearing, as 

 to render them dangerous, arose before the imagination. To have 

 adopted the method of Holmgren for the color-sense, by which an ac- 

 complished ophthalmic surgeon would conduct the examination of each 

 man, would have demanded years of his entire time, would have been 

 so tardy as to allow large additions to the force before it could be ac- 

 complished, and was soon rejected as impracticable ; neither was it 

 thought possible to train a sufficient number of the company's sur- 

 geons to perform this special task with fairness to the men and safety 

 to the company. To secure the co-operation of the employes the offi- 

 cers needed a system that could be applied locally on each division, 

 quietly and confidentially, and at the convenience of the men, without 

 compelling them to lose much time. Any undue publicity, or inex- 

 orable law that would compel the summary discharge of from ten to 

 fifteen per cent of their trained operatives, would have disorganized 

 the service, and destroyed the discipline of the company ; and for their 

 own protection, and as a duty to the public, the officers were willing to 

 put on trial any practicable scheme, without the pressure of any over- 

 anxious public opinion or hostile legislation. 



These, and other considerations of weight, led the writer to the 

 invention of an instrument for the examination of the color-sense, which 

 could be efficiently used by any intelligent, instructed official, and a 

 record of it permanently kept for the information of the officers, and 

 as a guide for the action of any surgical expert whom the road might 

 appoint to superintend the entire system. This consists of forty skeins 

 of wool, each one attached to a movable button, having figures from 

 1 to 40 inscribed on them, suspended from two flat sticks, so arranged 

 that the numbers are concealed. Holmgren's method of matching colors 

 is adhered to, and the test-colors to be matched are green, rose, and red : 

 the skeins from 1 to 20 being used for green, those from 21 to 30 for 

 rose, and from 31 to 40 for red ; upon the odd numbers are suspended 

 green, rose, and red skeins ; upon the even ones those " confusion 

 colors " which the experience of the writer had taught him would be 

 the most likely to be selected by the color-blind. In its use a green 

 skein is placed before the person at a few feet distant, and he is directed 

 to select those of that color from the stick, and to turn them away or 

 throw them over ; then the rose, then the red ; and as this is done 

 for each test-skein, the numbers upon the buttons are inspected and 

 recorded upon a blank. So simple is this system that the division 

 superintendent, who is responsible for the examination, may forget 



