100 C. V. L. CHARLIER, 
bution of the stars about the Z-axis, that the velocities of the stars 
are symmetrically distributed about the radius vector. The fact that 
the direction of the vertex is nearly perpendicular to the radius vector 
of the sun from the centre seems to indicate that the stars have a 
preferential motion perpendicular to the radius vector (of each star). For 
investigating whether this holds true for the B-stars I have computed 
the components of the velocity of each star along the radius vector 
and perpendicular to this direction. 
Let as before U?, V? and W° denote the components of the 
velocities of a star referred to the sun. Subtracting the mean values 
of these components they are freed from the velocity of the sun and 
we obtain what could be called the components of the velocity relatively 
to the centre, We denote them by U‘, V* and W‘, so that, using the 
results of the preceding 8, 
U ZU OK 
PAP AL 
We = Wea La. 
Let r, denote the projection of the radius vector upon the XY- 
plane and let y be the angle between this projection and the Y-axis: 
then we have 
| 
y € gy + daa s 
i = LME AUS 
Dividing by r, we obtain the components of the velocity of a 
star along the radius vector (more strictly along the projection of the 
radius vector in the XY-plane) and perpendicular to it, These com- 
ponents 
gn. and ur: ag 
dt 
are given in the columns 7 and 8 of table 17 above. 
nié: 
— ———— 
puc --— 
br Gad 
