148 EXPERIMENTS ON COLOUR, AS PERCEIVED BY THE EYE. 



of which one eye is green and the other red, I have found, when looking at 

 an arrangement of green and red papers, that some looked metallic and others 

 transparent. This arises from the very different relations of brightness of the 

 two colours as seen by each eye through the spectacles, which suggests the false 

 conclusion, that these differences are the result of reflection from a polished 

 surface, or of light transmitted through a clear one. 



NOTE IT. 

 liesults of Experiments with Mr Hay's Papers at Cambridge, November, 1854. 



The mean of ten observations made by six observers gave 



449R+-299 G + -252 B='224 W+ 776 Bk (1). 



696 R+-304 G = '181 B+-327 Y + '492 Bk (2). 



These two equations served to determine the positions of white and yellow 

 in diagram No. 2. The coefficient of W is 4 '447, and that of yellow 2'506. 



From these data we may deduce three other equations, either by calcu- 

 lation, or by measurement on the diagram (No. 2). 



Eliminating green from the equations, we find 



565 B + -435 Y = -307 R+'304 W + -389 Bk (3). 



The mean of three observations by three different observers gives 



573 B + -477 Y='313 R + -297 W+'390Bk. 

 Errors of calculation - -008 B + '008 Y - '006 R + '007 W - '001 Bk. 



The point on the diagram to which this equation corresponds is the intersec- 

 tion of the lines BY and RW, and the resultant tint is a pinkish -gray. 



Eliminating red from the equations, we obtain 



Calculation -533 B + '150 G + -317 Y = '337 W + -663 Bk 



By 10 observations '537 B+'146 G+'317 Y='337 W + -663 Bk 

 Errors -'004 +'004 



K 1 in i i nating blue '660 R + -340 G = '218 Y + '108 W + -682 Bk" 



' (5). 



By 5 observations '672 R + -328 G = '224 Y + '094 W + '672 Bk 

 Errors -'012 +'012 -'006 +'014 +'008 



