A. RITCFIIE-SCOTT 103 
By straightforward differentiation we find that 
^Nf^-hHA-'-^) (38), 
9X 
dr 
dj 
N 
1 _ ,,.2 
{,• + "'- 
h — rh 
dh dr 
dh 
] - r2 
d^f 
Ic — rh 
dkdr 
dh 
1 - r^ 
32/ 
3/ 
dhdk 
dr 
X 
1 - r2 
.(40), 
■(41). 
■(42), 
.(43). 
Hence summing for all samples aiid dividing by the number of samples and 
denoting this operation by we have, since quantities of the first order dis- 
appear, an equation involving ^ {dh)~, ^ {dhdk), etc. We may determine these 
values thus: 
77 dnig. 
' ^ NW, ' 

• Snnilarly ^ (^Z-^)2 ^ _^__J1_ (45), 
* f 
* (""A) ("11^)^-^-1^ («). 
To find (dhdr) we have 
— xdr Asfdin^. + B^.fdni.t — dni^^, 
.-. - xNH, ^ (drdh,) = A,t ^ (din,.)^ + B,^ ^ {d,n,.d>n.t) - ^ (din^fdm.,) 
^^...«,.(i-^)H-i;.,(»„-'^)-»,.,(.-^) (-17). 
After simphfication this becomes 
