1418 
system, the origin of which is consequently situated in the centre 
of gravity of the system of points, while the total moment of 
momentum continuously vanishes (§ 2). 
mal, = X, fi Conor B Lai er) 
Zina == 0 9S mya 0 ail OS Aeleniiye 10a) 
Sn (tay a a er ee 
First we pass to a second system of axes, with its origin perma- 
nently in point 1 of the system of points and which is continuously 
parallel to the principal system, for this second system holds: 
Pg tA al esd el IGN se! (6 
my m 
=m J m (ay — ye) — (Eme Emy — Emy Emo)=0. (12) 
(106), becomes (12) because according to (10a) 2’, Sm = — Ema, 
y' =m = — J my. 
If we take a third system of axes with its origin also in point 1 
and its axis of X permanently through point 2, and indicate the 
velocity of rotation of the third system of axes with respect to the 
second by one w, the equations (11) and (12) pass after transform- 
ation into the final equations (9a) and (6). Now w can be con- 
sidered as an auxiliary quantity, that can be substituted from (96) 
into (9a). . 
For the transformations of § 3 the first system of axes can also 
be chosen with its origin in the centre of gravity of the system of 
points, the calculations are quite analogous, however more complicated. 
