1 8 R. F. GWYTHEK, Specification of the elements of stress. 



which brings the notation into accordance with that used 

 for cartesian coordinates. 



The strain represented b}- F is a " pure " strain, and 



the principle of continuity will justify us in requiring that 



the whole "condensation" is given by this strain, and 



consequently that 



a>i I 3(2^ 1 -;<■>) I c>, 07,:, , 



cr- r or ?- ch' cs- ^^^' 



The relations may now be written 



nn = -— + -LI + ^J: — L' J 

 cr cr r 



I djF I cu., 

 /• dH red 



cF III., 

 niv — ^- -f- ^ 

 cz cz 



with the condition 



^^^^-^^^0 (34). 



« \c/- 8;-' /• rr ?' / 



;? \r ?A- ?- (•(^" r cr ?' f" cd' / 



F'=^-i^x^F-,.ri^+':tA (35). 



n \cz- cz- / 



r, , f. ■■ . f\cF I c-F c^F\ 

 \r cr ■/- cd- cz- J 



r cr f- oti- cz- 



Q - p{F+ ^i,) + 2(ff+ '^) + fi,.,, + ^,,) + ^^(;., + ,,3) = 0. 

 \or- cO-y Cr- cz 



\cr- r cr ?- cd- J cr- 



r cr ?2 cy- /- cr 



