66 II INDUCTION IN ROTATING SPHERES and at the boundary аф др = - (m+n+1) p" (p² m Xn Əz - nzXn Now satisfies these conditions. For we have, firstly, ə v³¢ = − œ[ v³(p»+s³X« ) − 2 n = (p″xn) – nov"(p™xn)] - - - az --∞[pm Jxn Əz {(m+2)(m+2n + 1) − 2n} - Deduc- tions. − nzp™-2X₂{m(m+2n+1)+2m} - m- - − − ∞{m(m + 2n + 3)p*-*(p?x« – n=x«n) + 2(n+1)p?x=}, = – n²x») Əz - - so that the first condition is satisfied; secondly, is the pro- duct of p+n+1 by a function of the angles, thus Эф a$ _m+n+¹p, მ ap P From this so that the second condition also is satisfied. correct value of the values of u', v', w' follow by the original differential equations, at first in a more complicated form. But the same form has already occurred on p. 43, and has already been shown to be identical with the one given above. This theorem leads to the following propositions:- 1. In the theorem we may replace pm by a series of powers of p, each power multiplied by an arbitrary constant, that is, for pm we may substitute any arbitrary function of p. And again, we may replace Xn by a series of spherical har- monics of different degrees with arbitrary coefficients; for n is without effect on the final result. Hence we get the following generalisation of the theorem :- If x is an arbitrary function, and if U = ox მა V = x W dwy then the currents u', v', w' induced by U, u' = - wax v = K dwz ω - @ax' K dwy = го ax dw₂ V, W are = - ω όχι ལེ་ K Jwz