touching his Theory of Light and Colours. 209 



nj3, BC; the second yS, DG; the third A$, FL; the fourth 

 «■/«,, mP; the fifth pv, »R; the sixth er£, XS, &c. : in all 

 which the deepest violet must be reflected at the inward edges 



S 



Gx 



L e p. R 



sill: 



a ilia 



. 

 represented by the pricked lines, where it would be reflected 

 were it alone, and the deepest red at the outward edges re- 

 presented by the black lines, where it would be reflected were 

 it alone, and all intermediate colours at those places in order 

 between these edges at which they would be reflected were 

 they alone ; each of them in a dark room parted from all other 

 colours by the refraction of a prism. And because the squares 

 of the semi-diameters of the outward verges AC, AG, AL, 

 &c, as also of A>j, Ay, A A, &c, the semi-diameters of the 

 inward are in arithmetical progression of the numbers 1, 3, 

 5, 7, 9, 11, &c; and the squares of the inward are to the 

 squares of the outward (Aij 2 to AC 2 , Ay 2 to AG 2 , A A 2 

 to AL 2 , &c.) as 9 to 14 (as I have found by measuring them 

 carefully and often, and comparing the observations); there- 

 fore the outward red verge of the second ring, and inward 

 violet one of the third, shall border upon one another (as you 

 may know by computation and see them represented in the 

 figure), and the like edges of the third and fourth rings shall 

 interfere, and those of the fourth and fifth interfere more, and 



