140 Mr GREEN, ON THE PROPAGATION OF LIGHT, &c. 



determine the values of A, B, &c., by the same condition which enabled 

 us to deduce the system (12, 1), we shall have, in the place of this 

 system, the following: 



1 = K(a* + if + O - \La? + My 2 + iW + 2 Py% + 2 Qxx + 2 Rxy\. . 



(15.) 

 = ax + by + ex, 



which is applicable to the more general case just considered. 



