1893.] Elasticity of a Crystal according to Boscovich. , 



"1 



Y 



J 



(4). 



9. In our dynamical treatment below, the following formulas, in 

 which powers higher than squares or products of the infinitesimal 

 ratios dx/r, fy/r, dzjr (? denoting OP) are neglected, will be found 

 useful. 



-f + 



+ yfy + zfa 



Now by (4) we have 



xlx -f yty +z$z = 



2 + ayz + lzx + cxy ---- (6), 



and 



Using (6) and (7) in (5), we find 



- 



e,f, g, a, 6,c). . (8), 



where Q denotes a quadratic function of e,/, &c., with coefficients as 

 follows : 



Coefficient of e 2 is ~ _ 



*- - 



x~yz 



r ^ 



(9), 



J 



