262 
Peccavimus ! 
Hence the correction to be applied to the value of M-, in formula (39) is the 
mean value of SA'-i?. 
Now 
and 
so that 
n, 
I , 7 . ( "~ 1) J ~.> 
II ^ 
A"' = \s{dniX^' + 'Idn.dntX.^'X,") - S {dn.dxXi') + ur,jru-id.&. 
Let us write A- = L + M + X and B = U + K. 
HL 
S {Xr^'dn^'dx) + S {X/"Xt"-'dn,hlntdx} 
+ 2S ( X,'''-'Xt"dns'dntdx) + 2S {dn^ntdn^MXi'-'Xt^'X/)^ 
Denoting the mean value iAHL by HL we have (see (31), (32), (33) of paper cited) 
HL = - , 
01 3 
3N 
- 2^' 
X^"}+S 
[V 71 n- ' 
_ 2S 1^,"^^ (A, + Xt + A,,) AV 
+ [''■^■'-' {Xrx,- + 2Z/"-ix,«+^ - - 2a;/«a^«)1 
3^ 1"^^'^^^" 
,5 (Z/"Z," + 2Z,,^"->X,"+') 
6' j'-^' (2A7'^+'Xi"-' + ^AV" A't") 
_ 2;S |^^^(3A;'AV'AV'+ A';'+^AV'-^AV')} 
+ 3/^ X/") + >^ j'^ (X -X,- + 2X --'X,"+')} 
