297 
(5) PE (Le) x) 1—e 2 
dv EME eee qe lr’ ree oe 
(ay: (tl + ®) 4 NEE 
in which g=w( +2 =, i+ Sr ken (see 
above). In mercury, where den 1—e will, therefore, always be 
negative at 7’, hence also de/,. 
_$ 18. Calculation of some Numerical Values. 
The value of x being always very small at 7, we way write 
approximately for (4), when 1—r—1 and 1 rn is put: 
3(1+-1e(9—2)) + B(L—T0)'= leen (1—ry)? —w (v1)? | 
and from this follows for r ee ‚when wis small (see abov °)); 
2 (1—b’)’ 
20 
ee — (848 (1—ro)*) 
ied EN 
ST 
gate Delen ig En ee 
gezo Site] 
Spe) (lt) + =e“) 
With very small values of « also 1 — rg can be put =1, and 
we have approximately: 
ko nh 
he em On ed 
> (Se 
ple) — (el) + wel)" 
With small « we way write 1: 2(1—d’) for w. Now o is large 
(6 or 7), and it can easily be calculated that in the denominator 
the two first terms may be neglected by the side of w (e—1)’, provided 
the latter is provided with a factor about 1,35. When we also write 
ontor 1, — ee 
—1 
7) zat Ee =| becomes O at « = O (tx = 0) and or is 
then = we get: 
