300 
For «= —a (greatest deviation to the side of P) everything is 
just the opposite, and we have: 
a’? F:e? = (-- 0,1134) — 0,0151 = — 0,1285, 
Now the repulsive force predominates, which P exerts on J. 
2. z—='/,a. This is a mean position of M between O and the 
perfect contact at z = a. 
For «=0O we have here, since 2'/, : (5'/,% — (1: 6'/,) = 
— 0,2078 — 0,16 — 0,0478, and 3'/, : (117/)% — 1: 12) = 
= 0,09276 — 0,08163 = 0,0111: 
a? F's e? — (0,0478—0,0478) — (0,0111—0,0111) = 0-0 =0. 
For «=a we find: 
a’ I’:e?=(0,0478—0,0111)—(0,0111—0,0478)—0,0366—(—0,0366)—0,0732. 
Here the attractive force of P supports the repulsive force of Q 
(which happens to have the same value). 
Finally «= —a yields with J'/, : (1*/,)% — (1 : 2'/,) = 1,0733 — 
— 0,4444 — 0,6289, and 4'/, : (19'/,)% — (4: 20'/,) = 0,0533 — 
— 0,0494 — 0,0039: 
a? F’;e?=(0,0478—0,6289)—(0,0111—0,0039)=(—0,5811)—0,0072=— 0,5883. 
It will be seen that the action is now quite asymmetric: that towards 
the right at e—-+a is much weaker than that towards the left at 
x—=—a. This is, of course, owing to the fact that in this latter 
position the electron is much nearer P than it is to Q in the case 
x=ta. 
3. z=a. This is the extreme position of M close to P (distance 
of the centres = 2a), in which we sball now find an infinitely 
great repulsive force at «——a. 
In’ the ‘case ‘« = 0 we get: 
a'F:e* = (0,1349 0,1349) — (0,0064—0,0064) = 0—0 — 0. 
For «= +a we find: 
a’ F : e?=(0,13849—0,0215)—(0,0064—0,0215)—0,1134—(—0,0151)—0,1285. 
And x—=—a yields with (1 : 0%) — (1:1) = @ —1, and 
(5 : 24%) — (1 : 25) = 0,0425 — 0,04 = 0,0025 : 
at Fs? = (0,1349 — co) — (0,0064—0,0025) = (— ow) — 0,0039 = — oo. 
The above can be combined in the following survey (values of 
a Be). 
