1010 
If we compare this with (14), and moreover put r3;=1, then 
BE NEE = 
B HS) = Tr gags Ot Ea ot opaae 
The function 
S= a + Beos y(y+C) 
solves this differential equation by suitable choice of the values 
a, B, and 7; we can take the integration constant C'to be zero, as this 
choice only determines from where we measure g. The function 
S= a + Beos y¢ 
satisfies the differential equation, if 
- (14-2) = 2 _ 2) 4,2 aoe Ba Dh A 
en ee y (raat 
Instead of the integration constants 7 and A, which we introduced 
before, we can now consider « and 3 as such. y differs from 1 
only in terms of the second order, and therefore the equation 
k 
Die wre 
is accurate up to terms of the second order. 
We may, therefore, use the value of A’c*, which follows from 
this, for the caleulation of y, and so we find 
2 
bk 
y=l— 2 a, 
and from this 
] dk 
—_—1=>—a. 
Y 4e? 
If we now put yp ==, then 
ok 
aia 
and 
1 
SBER oe 8. aa 
E 
This is the equation of a conic section in polar coordinates. 
The angle 5 hkay/4c?, between the major axis and the fixed 
line gy =O, is proportional to the angle wy, between the radius 
vector and the major axis. For one revolution the ‘motion of the 
perihelium’ is 450 ke/c* degrees; it depends only on the parameter 
l/a of the orbit. As Prof. pr Srrrer has calculated from equations 
of motion determined by Prof. Lorentz, it amounts for Mercurius 
to 18" per century, the observed motion being 44”. It is 
worthy of note that the motion of the perihelium does not depend 
