(490) 
d? 
el >0. But for y=0, which would belong to n=41, the first 
(dj 
ER. dp 
member =O and the second =1. So for this limiting case —, <0 
v 
So there is a transition value of n, namely for that which belongs 
1 
o-r 1 or = AD According to Contribution III the value of z 
is about 0.41 and of n about 3.4 for this value of y. 
For the points of the tangent for which a= 0, the condition is: 
1 = 4y? 
1 (l—y)? < 1+ 
ae 
y 
or 
02 4y? — By 4 1 
or 
OZ =: Bayt a): 
So this inequality can never be satisfied by the sign >; only for 
1 
Us there is equality, as we saw already above. We conclude from 
= 0 disappears in 
d 
this that however great the value of 7 be, 5 
d 
er is negative for all the points of the tangents. 
v 
the region where 
So this is a fortiori the case for all the points above the tangent. 
1 
When y lies between = and and so n > 3.4, a line is to be 
9’ 
ol 
indicated parallel to the tangent on which the points (¢, , ¢,) must 
p) d? 
hie) tor ED to disappear, just on the verge of me But 
da? dv? 
1 
for values of 4 = and n < 3.4 the disappearance will take place 
dp 
where 
dv? 
is negative for all the points below the parabola, and so 
3 2 
VS 0 will he inde ten 
Dig dv? 
perature below 7, so before the first contact, and at a temperature 
above 7,, so after the second contact. The place of the straight 
line which contains the points at which the transition of the sign of 
d 
the curve == 0 both at-a tem- 
