ASTRONOMY: G. STROM BERG 
39 
The position found for the axes of preferential motion is in good agree- 
ment with other determinations which, according to the summary by Edding- 
ton, give a = 94°, 8 = +12°. 
The asymmetrical terms, or those of odd order, are next determined sepa- 
rately for the three groups. If those which depend only on the galactic lati- 
tude are considered, we obtain expressions for 9 from which the following 
maximum values may be derived : 
GROUP I 
GROUP II 
GROUP III 
b 
d 
b 
b 
km. 
13.9 
-19?1 
km. 
19.7 
-19?9 
km. 
28.4 
-22?8 
We find, accordingly, in all cases a negative latitude for the maximum fl- 
it is known, however, that the sun is situated north of the real galactic plane? 
the distance being about 20 parsecs, 7 or a distance corresponding to a parallax 
of 0".05. This indicates a maximum of motion, not in the galactic equator, 
but in the real galactic plane. The form of the surface for the second group 
is shown in figure 1 . 
The surfaces which represent the average radial velocity for the first and 
second groups are very nearly the same, the most important features being 
two large terms of second and third order. These are as follows, b and / 
being the galactic latitude and longitude, respectively: 
SECOND ORDER 
THIRD ORDER 
Group I 
2 
59 cos' 2 b cos 2 (7 — 
174?3) 
2 
90 cos 3 
b cos 3 (/ — 
76?0) 
Group II 
3 
18 cos' 2 b cos 2 (Z — 
162?7) 
3 
10 cos 3 
b cos 3 (/ — 
77?6) 
The second order terms define the stream motion, and the existence of the 
large third order terms shows that the axes of maximum radial velocity do not 
lie in a straight line. 
The two principal maxima of 6 in the two surfaces are 
I 
b 
a 
8 
/ 
b 
a 
8 
km. 
km. 
Group I 
19.60 
190° 
+ 4° 
109° 
-7° 
17.50 
324° 
- 2° 
264° 
-33° 
Group II 
24.23 
179 
-18 
84 
-7 
26.33 
322 
-19 
283 
-41 
We find, therefore, that the axes of largest radial mobility, which may be 
assumed to correspond approximately to the direction of preferential motion 
in space, form obtuse angles equal to 134° and 128°, respectively, for the two 
