Illustrate the Propagation of Light in Biaxals 327 



The curves 1*53, 1'53 are the sections by a plane through 

 the singular points, parallel to the ZOY plane. 



Section through Singular Points parallel to the XOY plane. 



Inner. Outer. 



z. y. z. y- 



0-00 1-29 0-00 3-44 



1-00 1-15 1-00 3-28 



1-44 1-00 



2-00 0-66 2-00 



2-83 

 0-00 2-58 



2-58 



2-71 



1-00 



0-00 



and 1-98 



A section taken through the axis of z and at 45° to the 



Fis. 7. 



axes of x and y is given in fig. 7. These curves could have 

 been obtained bv means of fig. 4, but as a check on the 



2 A2 



