40 
ASTRONOMY: G. STROMBERG 
groups, and that there is a pronounced minimum at longitude 258°. The 
nearest approach to a symmetrical plane at right angles to the galacticplane 
has the longitude 
258?6 for Group I and 256?6 for Group II. 
270* 
20 
KM- 
AtC- 
In figures 2 and 3 are shown the intersections between the radial velocity 
surfaces and the galactic equator. The dotted curves indicate the intersec- 
tions when only terms of even order are considered, and the arrows mark the 
position of the symmetrical planes. 
The properties of these surfaces may be explained on the assumption that 
