112 ^ The Rev. S. Haughton on a Classification of Elastic Media, 



' ^<^ - ^'' ^ d? + ^'^ '' f/1/= + ^'^ '' ti^^ 



/ N d'^ / X f'^'? / X d"^ 



+ («,0^+(«.C.)5^+(«3C3)^ 



+ (6,,3 + 63C.) |j + (6,C3 + 63CJ ^^ + {he, + b,c,) |;|. 



By combining these equations with (12), and comparing (4), we obtain from the 

 function F = 0, + (p, the following equations of motion, 



These are the equations of small oscillations of all media, for which the direct 

 influence of the external forces may be neglected. 



In equations (14) it will be observed that nine of the coefficients are 



