( 701 ) 
: ea 7 De 5 ad “ e se =i . v 
can be = 7. With constantly rising value of n, the quantity 5 
can, indeed, increase indefinitely, in which, however, 7’ becomes an 
ever smaller fraction of 7). The value, however, which &, and 
# 7 VV Java r U 
€, will have, and consequently the value of 2, and 7, cannot be 
chosen arbitrarily. Besides that «, and e,‚ must have such a value 
that the point denoted by them, lies on the parabola OPQ, the 
condition must also be fulfilled that a, = /a,a,. For the case that 
? =1, the values of ¢, and e, are easy to calculate. Then the point 
(€,,&,) must also lie on a second parabola, congruent with PO, 
and shifted by an amount 1 along the ¢, and ¢,-axis in negative 
direction. These parabolae having their axes parallel, there will only 
be a single point of intersection. The equations which are to be 
satisfied, are then: 
(e, — ne) = 4n'(n — 1) (e, — ne) 
and 
Erne, tn — 1)? = 4ufn — 1) (Ee, — ne, FR — 1). 
Then we find: 
n+3 
ee Feeye 
and 
on+1 
n he ay Tren ales 1), 
n+3 A da+1 
. ea ——— £ tE 7 i 
or w m+) and x Tmt) The value of 7 obtained in 
this case is smaller than the one calculated above if we take e‚ =e,. 
If <1, e, increases, of course, and «, decreases and reversely. A 
value of / might be chosen so that 7’ assumes a maximum value, 
but to this we come back later on. But in any case the values of 
| dy dw 
&, and ¢, may be such that the two surfaces —- ==0 and — 
da” dv? 
touch only at one single temperature, without intersecting further. 
And if ” is not very large, this temperature lies very low. Thus from 
v—b\? 
(=) 
ans Moe 
, and the supposition /=1 we cal- 
the formula MRT = 2 - 
b 
‘i 1 
culate for n = 2 the value of De Td about, and for other values 
k 
