Remarks on Railway and Marine Signals. 125 



constantly running over almost the same track of ocean at a 

 speed often of sixteen or eighteen knots an hour ; or if one 

 observes the succession of trains at a large railway station 

 like the Victoria, in London, one is likely not to underrate 

 the necessity of increasing vigilance and perfect physical 

 capability on the part of the signallers and look-out men 

 and the drivers of trains. Very little reflection suggests the 

 necessity of using a code of signals suited as regards size 

 and colour to the optical capacities of the normal eye, as 

 these have been determined by scientific examination. Of 

 course this has already been partly attended to long ago in 

 a rough way, but by no means with the accuracy which the 

 subject now both permits and demands. Almost equally 

 apparent is it that the signals should be, at least in the case 

 of ocean steamers and railway lines of coterminous countries, 

 not national but international. 



Another at least equally important condition requisite to 

 ensure safety in travelling is visual competency on the part 

 of all those who are engaged in signalling or in looking out 

 for signals. 



The essential requirements therefore are : — 



1. A series of signals for sea, to be agreed upon and ac- 

 cepted by all maritime nations ; and, further, an uniformity 

 as to size, colour, and signification of land (railway) signals. 



2. That these signals should be in relation with the visual 

 acuity and colour perception of the normal human eye. 



3. That no signallers or observers should be employed who 

 do not come up to a certain fixed standard of visual acuity, 

 refraction, and colour sense. 



In regard to the first of these requirements, the necessity 

 of a commission of delegates from the principal maritime 

 Governments was strongly urged by the International 

 Medical Congress of 1881, in order to secure uniformity in 

 size, colour, and disposition of signal lights. Such a com- 

 mission would at the same time ensure the conditions 

 required under the second heading. But there should be no 

 delay in carrying out the third requirement. This is abso- 

 lutely essential to the safety of life of the travelling popula- 

 tion. 



It might be thought that nothing can be easier than to 

 decide, with but little trouble or method, whether a person 

 has good sight and good perception of colours. In a very 

 small percentage of those who would present themselves for 

 examination this question might, perhaps, be at once decided 



