74 MR. J. SMITH ON THE ORIGIN OF COLOUR 



its termiuation, or vice versa ; if we make this supposition, 

 we shall have no difficulty, on examining the motion, to 

 account for the change of colour on the change of motion, 

 however strange the phenomenon may at first sight ap- 

 pear. The direction of the ray of light is an important 

 element in all these phenomena. When the light in- 

 creases, or, which is the same thing, when it comes after 

 the shade during the motion of the disc, then the colour 

 is red or allied to red. When the shade follows the light, 

 or which is the same thing, when the light decreases, the 

 colours are allied to blue ; and all colour is only a modifi- 

 cation of these two conditions of the ether or a combination 

 of the two. No more has hitherto been made of the sub- 

 ject of colour, analyse it as much as we please. Every 

 sensation is reduced to one or other of these two con- 

 ditions, infinitely diversified by an infinite wisdom. 



113. The experiment just described I consider as not 

 only very remarkable and very beautiful, but also as highly 

 instructive. There will, however, arise in the minds of 

 some who have long and profoundly studied the subject of 

 light, and who are much more conversant with its details 

 than I am, but who are wedded to the science of the day, 

 the question — Is not this, after all, only the effect of the 

 polarization of light? I am not about to discuss this 

 point at present, but I would ask those who are unwilling 

 to accept new ideas to explain these phenomena on any 

 old hypothesis; for until this is done, they must for ever 

 remain a stumbliug block in the path of science. They 

 are incontestible facts, not illusions, and cannot be ex- 

 plained away by any empirical law or antiquated scientific 

 conventionalism. 



Remarks. 



114. Although by operating with discs, having definite 

 proportions of white and black on them, colours were pro- 



