80 G. PLARR ON THE SOLUTION OF THE EQUATION Vp¢p=0. 
Bor b= h6 = = nae , the spherical conic is a circle belonging 

to the third sheet, and whose plane is also in R. 
; 1 
The normal vector v, owing to W, = — 5h., becomes 
7 
Uj (w+ 5hs)e > 
and for the direction ¢ situated in the plane of the circle, namely for (66) 
Mie’ = (An/eq + vv e,) + wN, 
Moy, = [(= + 17.) h Je, + (w + bh)ove, | 
= (w + : h,) BN,, 
we get 
namely 
Mir = [X(in+ pho) er + (hs + 5h2) Ve, J+ m3 hd . 
But we have 
(14 + 1 ig) + (Eby + te) = 0, 
hi+5 28 — 5 (ahs) = = By, OF Gis 
and 
Thus 
Miv, = [AaJer— valey Jey + : hoN, . 
If we compare this to v, (64) 
M, vu. = (AJe, _ ve), 
and calculate cos vv, we get 
g / ° as, 
for. we = 90° 5» Gos ge & 2G 
F “aS “N ° 
for pe = 0', COS a0, = "05 vv, = (907; 
§ 12. We must, at least for form’s sake, not loose sight of the question 
which we put to ourselves at the end of § 7, and which is of easy solution now 
that we have sketched an outline of the principal features of the surface '=0, 
although we have not by far exhausted the subject, namely : 
