64 11 INDUCTION IN ROTATING SPHERES Theorem which forms the basis of what follows. If we remember that Əx au av aw + + მყ Əz =3 0, we get for these conditions:- In the material of the shell av au V² = 2w +w(xV²V − yV²U) ; - дх მიყ and at the boundaries 24 P av au W др = We shall first demonstrate the following theorem :— If U, V, W have the forms эх ду m U = py- Əz ду V = p2 m Xn дх #xt). W = y дх m X ду which forms satisfy the equation au av aw + + მყ Əz მე = 0, then the solutions of the preceding differential equations are φ u' = - opm(p?? = wpm+1 sin = = V = - W m K Y dxn - nzxn Əz Əz - 2 dy მა