3l8 On the Powefs af the pr'ifuhattc Colour i 



hefs, while on and near tHe circumference, it appeared to tak?l 

 a deeper hue. 



An objeft fo well divided by nature into very minute and 

 differently arranged points, on which the attention might be 

 fixed, in order to afcertain whether they would be equally 

 eliftinft in all colours, and whether their number would be; 

 increafed or diminllhed by different degrees of illumination, 

 was exadly what I wanted; nor could I think it lefs re- 

 markable, that all the other objefts I had fixed upon, befideS 

 many more which have" been examined, fuch a§ copper, tin, 

 filver, 8cc. preferiled themfolves nearly with the fame ap- 

 pearance. In the brafs, which had been turned in a lathe, 

 the luminous points were arranged in furrows; and in tin 

 they were remarkably beautiful. The rcfult of the exami- 

 nation of my obje6ls was as follows : 



■xd Experlnienf. Red paper.— In the red rays I view i 

 iright point near an accidental black fpot in the paper; 

 which fervesrae as a mark; and I notice the fpace between the 

 point and the fpot \ it contains feveral faint points ; Tn the 

 brange rays I fee better ; the bi-ight point I now perceive is 

 tloubic : in the yello'.v rays, I fee the objeft ftlll better: In 

 the green rays, full as well ris before : In the blue rays, very 

 well : In the indigo rays, not quile fo well as in the blue: Iii 

 the violet rays very imperfe6lly. 



3^ Experhnent. Green paper:-^7?«?^. t fix my attention 

 bn many faint fpots in a fpace between two bright double 

 |)oints. — Orange. I fee thofe faint points better. — Yelloiu. Still 

 better. — Green. As well as before; I fee remarkably well.-^» 

 Blue. Lefs bright, but very dhiin«Sl. — Indigo. Not well. — 

 Viblet. Bad. 



^th Experiment. A piece of very clean turned brafs. — ■ 

 i?. I remark feveral faint luminoiis points between two bright 

 bnes; the colour of the brafs makes the red rays appear like 

 brange. — 0. I fee better, btU the orange colour is likewife 

 dlfi'erent from what it ought to be ; However, this is not 

 at prefcnl the objeiSl: of my inveftigation. — Y. I fee ftlll 

 belter. — G. I fee full as well as before. — B. t do not fee fd 

 well now. — /. 1 cannot fee well. — K Bad. 



^th Experiment, A liail. — R, I i-cmark two bright points 



and 



