116 HABIT AND INTELLIGENCE. [cii. XXXV. 



those of tlie spectrum in intensity and in degi'ee of saturation 

 that the eye does not identify them. 



There are three, and only three, ways in which any two tints 

 of colour can possibly differ from each other. These are : 



1. In the order of the colour : or, in other words, the posi- 

 tion of the colour in the chromatic circle. 



2. In the intensity of the colour. And 



3. In the intensity of the white with which the colours of 

 all substances are diluted. 



Professor Clark Maxwell has made the important remark, 



Possibility that, as these three elements aU admit of numerical statement, 



of giviug a -J. jg possible to give an arithmetical formula for any possible 



for any tint. The intensity, or brightness, of the colour itself and of 



*^°*" the intermixed white may of course be numerically valued, 



taking as unity for each colour the brightest tint that can be 



obtained by means of pigments. The order of the colour may 



be stated in degrees of the chromatic circle, which for such a 



purpose ought probably to be so arranged that each colour 



should be exactly 180° from its complementary. 



Scientific I am convinced that the principles of harmonious colouring 



principles ^j.g ^q Ijq found in the laws of the combination of colours stated 



of harino- r- ^r -r~, t ■ • ■ ■, • 



nious in this note. I do not know how lar Mr. Kuskin is right in 



colouring, saying that no rules for harmonious colouring are worth any- 

 thing, but if he is right that no such rules of any value have 

 been yet laid down, it does not follow that he is right in main- 

 taining it to be in the nature of things impossible for sucli 

 rules ever to be discovered. If we have no rules of any value 

 for harmonious colouring, this is only because the true laws of 

 the combination of colours have not been long known. We 

 know what science has done for the kindred art of music, and 

 with this analogy it is to me incredible that science should 

 be unable to discover valid and valuable rules for the art of 

 colouring. 



