( 208 ) 



equation may assume the following form : 



B w g (Sa g —l) 1 



C l—2af g n—\ 



This equation may also be derived by the following consideration. 



d 2 ip dp 



If the top of =0 is also to be a point of — = 0, the following 



dx* dx 



d*ty d'ty d'ty 



equations are to be satisfied : — — = , -— — = , — 0, and 



ax- „t dx v 'f dvdx* 



d 2 ty dp 



= 0. It appears from this, that not only — = is to be satisfied 



dxdv dx 



d 2 p /dp\ 



but also — = 0. This means that the point of the curve — 1 =0 

 dx" \dxjc2 



at which this curve has its minimum volume, must pass through 



the top. So the following equations must be satisfied : 



db da 



MRT — — 



dx dx 



and 



and so also 



MRT. 



. dx 

 2 



(v—b)- *>' 

 'dbY d*a 



{v-by v* 



da 



v — b dx B 



db dra C 

 2— — 

 dx dor 



Now for the top of = (Contribution III p. 829) the equation 



dx" 



- I V% 2 (! — X «T l _ 'V | t/ xg'jl — a:,,)* 



[/ 4(1 — 2*7 en n — 1 "" 1 — 2x tl ' V 4(1 — 2x u ) 



'db\ V 4(1 



dx 



holds. Hence 



or 



B V 1 



C + Xq 1— 2x„ n—l 



B x„(3x g — 1) 1 



C 1— 2.x g n — l 



If if were possible to express % as explicit function of n, it would 



