THE EQUILIBRIUM OF ELASTIC SOLIDS. 



67 



A l G^ = A- L A t , and two loops surrounding B^ and B 2 ; the other curves, for which 

 -^=lV> ^r, &c., consist each of two ovals surrounding B r and B z , and an 

 exterior portion surrounding all the former curves. 



Fig. 1. 



I have produced these curves in the jelly of isinglass described in Case I. 

 They are best seen by using circularly polarized light, as the curves are then 

 seen without interruption, and their resemblance to the calculated curves is 

 more apparent. To avoid crowding the curves toward the centre of the figure, 

 I have taken the values of / for the different curves, not in an arithmetical, 

 but in a geometrical progression, ascending by powers of 2. 



92 



