538 PROFESSOR KELLAND ON THE VIBRATIONS OF 



Equation I. gives 



<"-">{ '-e-'JEr 



1(1- . 



' 



2 a b i c 



_ a abi cos 2 (f> a 

 (a + b) (i+r) a + b 



' Y~ >*( Y) _ fl <* 6* cos 2 </) 6 



r (a 7)} {'Y r (" Y)} _ * 6 a a 6 1 cos 2 



(z + r) a (7-Y) 2 



Substituting, we obtain 





-r a cos 



a ~ b f N (*- r ) 2 (- i )(*-') J 'l 



t-r-.a^i-O-L^-V 8 A fl 



(' + r (a b} ,. v, 1 

 f + Q (* f 

 2r Sir ^ ) 



( tt + fc)^-r 2 ) f _a^_ a-6 



"^2a6ecos 2 ) S \ ~ (a + 5) 2 + (a + J) 2 



Taking this to two dimensions, to which alone it is correct, we have 



2i ,., 

 _(, 



( + i) i cos 2 



or 



_ 



(a + b) cos 2 



