138 Mr. Charles Tomlinson, on the Curved Figures 



A beautiful, but very simple, change in the apparent 

 figure of a striated disk is made by nxerely causing it to re- 

 volve, and viewing it in the usual way, without the mirror 

 apparatus. 



Fig. 2. 



represents the disk while stationary. Figure 2 a the disk 

 when simply revolving. 



The law which regulates the production of the rings, 

 figure 2 a. 



Fiof. 2 a. 



appears to be this : whatever tint predominates at any 

 point of the disk, the rapidity of revolution causes the same 

 tint to appear at every other point equidistant from the 

 centre ; and, to ascertain what that tint would be, describe 

 a concentric circle through that point, and by adding the 

 dark portions through which it would pass into one series, 

 and the light portions into another series, by combining the 

 two aggregates we may ascertain beforehand what number 

 of concentric circles will result : the outlines are, of course, 

 not defined, but melt into each other. 



