1112 
7 
v 
in such way that the terms with «’, y’ and 2’ vanish in the equations 
(14), ie. if: 
oz (1-55) = tbe a 3 (15) 
But in this case w’, y’, 2’ is extactly a geodesically moving system 
of axes as I demonstrated in the publication referred to on the 
every kind of motion with respect to 2’, y’ and 2’ if w be choosen 
. . : Ta 
first page. After one revolution this system has turned over R’ 
This can of course also be calculated in the fourdimensional way. 
Starting with the linear element (2) we find a precession passing 
for 8=O (velocity approaching to zero) in the above calculated 
value = and for gain’ 1°/, << this: value. 
[t is worth observing the ordinary precession gets. possibly also 
another value in relativistic mechanics than in classical mechanics, 
a possibility pointed out by pe Sitter. By means of the equations 
given by Fokker it will be possible to calculate the deviation caused 
by this, at least so far as it is not influenced by forces caused by 
the mutual attractions of the parts of the planet. 
