210 OLIVER— COLOR-SIGNALS IN MARINE SERVICE. [April 9, 



of certain places, should be given ; these to be submitted for 

 inspection on demand. 



IV. Every series of related colors used should be regulated, both 

 as to their comparative sizes of exposure and the relative degrees of 

 color saturation ; these should be duly proportionate in reference to 

 equalities, distinctness, relationships and association of safe dis- 

 tances, and with regard to differences in degrees of penetrability. 

 This can be accomplished either by having the color values 

 graded proportionately (a bad plan, since it tends to weaken the 

 value of the stronger colors), or by making the color areas relative 

 in size : for example, to give a green signal light a similar degree of 

 brightness, and hence the same relative distinctness (which governs 

 all apparent distances, and in consequence the relationships of 

 the two colors), as red, it must either be five times more power- 

 fully illuminated than the red or given five times more exposed 

 superficial area : so too with all other color changes ; there is an 

 idiocratic relationship. Clinical experiment has shown this, and 

 laboratory research has confirmed the practical findings. The 

 importance of this factor can hardly be overestimated when 

 the series of individual signal colors are numerous in well-filled and 

 busy harbors. 



These plans once agreed upon by such an international com- 

 mission, all necessary data will soon become common property, and 

 in consequen.ee the system will be universally understood. 



Philadelphia y April J ^ igo4* 



