1904.] OLIVER — COLOR-SIGNALS IN MARINE SERVICE. 209 



comparable with safety to large moving masses that often can be 

 alone stopped slowly and gradually — colors and relative positions 

 which must be carefully chosen in regard to distances, situ- 

 ations, etc. 



In the following paragraphs it has been endeavored to express 

 clearly and briefly the specific reasons for the improvements and 

 changes suggested. 



I. All of the color tints to be used both by reflected light- 

 stimuli and transmitted light-stimuli (day and night) during actual 

 duty, should be officially proven copies of standards which have 

 been carefully chosen in such a way that the signals may be uniform 

 in tint in spite of variations in the character of the illuminants 

 themselves. These selections should be made by an international 

 commission of normal-eyed color experts. The color-signals will 

 then be universally alike, thus minimizing danger from confusion 

 due to false color exposure. 



These results can probably best be obtained by mathematically 

 and analytically obtaining sample pigment hues, both for diffuse 

 reflected solar light and diffuse refracted artificial light, of specified 

 kinds, character, degrees and tints, which are equivalent to the 

 midway bands for the colors used in the corresponding portions of 

 the color spectra obtained during exposure to the illuminant to be 

 employed during actual service. 



II. Each vessel of any importance should be provided with pro- 

 portionately-sized miniature samples of color-boxes, color-lamps, 

 signal-colors, etc., — or better, fitted with full-sized examples of the 

 same, — all carefully protected and boxed. These should be used as 

 guides for the tinting of all material which employs color as 

 its basis for signalling of any kind. These materials should be 

 certified by proper authority, and should be obtainable at cost at 

 licensed shops in every port of any consequence. 



III. It should be a part of the official duty of every national, 

 state and municipal government to see that the materials which are 

 used for color-signalling in any form, as well as the samples, are 

 periodically examined as to cleanliness and stability of tint. 

 Dated certificates, brief and to the point, with plain instructions 

 for the easiest manufacture and the best plans for the preservation 

 of the color materials, together with clearly expressed rules for dis- 

 tances used, situations employed, and notes on any color peculiarity 



PROG. AMER. PHILOS. SCO. XLIII. 176. N. PRINTED JUNE 27, 1904. 



