264 Dr. Herschei/s Investigation of the Powers 



Their light was that of the illuminating colour, but differed 

 considerably in brightness ; some of the points being dim and 

 faint, while others were luminous and brilliant. The brightest 

 of them also, admitted of a little variation in their colour, or 

 rather in the intensity of the same colour ; for, in the centre of 

 some of the most brilliant of these lucid appearances, their light 

 had more vivacity, and seemed to deviate from the illuminating 

 tint towards whiteness, while on and near the circumference, it 

 appeared to take a deeper hue. 



An object so well divided by nature, into very minute and 

 differently-arranged points, on which the attention might be 

 fixed, in order to ascertain whether they would be equally 

 distinct in all colours, and whether their number would be 

 increased or diminished by different degrees of illumination, was 

 exactly what I wanted ; nor could I think it less remarkable, 

 that all the other objects I had fixed upon, besides many more 

 which have been examined, such as copper, tin, silver, &c. 

 presented themselves nearly with the same appearance. In the 

 brass, which had been turned in a lathe, the luminous points were 

 arranged in furrows; and in tin they were remarkably beautiful. 

 The result of the examination of my objects was as follows. 



zd Experi?nent. Red paper. 



In the red rays, I view a bright point near an accidental 

 black spot in the paper, which serves me as a mark; and I 

 notice the space between the point and the spot: it contains 

 several faint points. 



In the orange rays, I see better. The bright point, I now 

 perceive, is double. 



In the yellow rays, I see the object still better. 



In the green rays, full as well as before. 



