1 70 On the Decomposition of Light, 



is an augmentation of light by the union of the green and 

 violet ; but the effect is much less than in the preceding in- 

 stance, both froin the nature of those colours, and their ex- 

 tent, though there is some trace of it in the spectrum when 

 properly displayed. In short, I have not by tnis figure pre- 

 tended to exhibit any thing more than what may possibly 

 happen. For this reason I have limited the ordinalesof each 

 colour by a right line merely; for, as the law of their pro- 

 gression is not known, so that it is impossible to give the pre- 

 cise curve, I have adopted the simplest line as sufficient for 

 ijiy purpose. 



The striking agreement of my hypothesis with the pecu- 

 liarities of the spectrum excited me the more to apply it 

 to the dial of colours. This coloured figure has such sin- 

 gular properties, that the mind cannot easily bend itself to 

 them. How indeed can it conceive the existence of an infi- 

 nite number of luminous rays, all different yet equally sim- 

 ple? How is it, that taken in pairs from the extremities of 

 every diameter of the dial, that is, from any two opposite 

 poinf, they shall always form the same white ? For in- 

 stance, a certain red ray with a green gives white ; an 

 orange with a blue, the same ; a violet with a yellow, still 

 the same. VV^hat a strange similitude ! How again are the 

 seven distinct orders of the spectrum consistent with that 

 insensiiile blending of the tints of the dial recommended 

 by Newton, and in fact necessary ? Yet all these are so 

 completely supported by experiment, that their reality can- 

 not be questioned. 



I had therefore a problem to solve, the complicated data 

 of which seemed at first not to promise a simple solution ; 

 yet, after various attempts, I attained my object, as will b« 

 *een. 



[To be contiuued.j 



XXIV. On 



