418 
ASTRONOMY: W. S. ADAMS 
It is clear from these results that the radial velocity increases rapidly 
with proper motion. Only a few A type stars of very large proper mo- 
tion are known. Of those observed at Mount Wilson for which /x exceeds 
0'\20, two have velocities of over 150 km.; one has a velocity of 87 km.; 
and the average for the other six is 20 km. 
In view of this relationship between proper motion and radial velocity 
it becomes of especial interest to compare the Mount Wilson observa- 
tions of stars of small proper motion with the results of W. W. Campbell 
for stars selected on the basis of apparent magnitude alone. Table II 
contains the average values of the radial velocities corrected for solar 
motion, of 1034 stars published in Campbells' first table.^ No con- 
stant K has been applied to these results. The proper motions have 
been taken from Boss's catalogue for the individual stars appearing 
in Campbell's later lists, and hence the mean values are not strictly 
correct for the stars whose velocities are given. Since the number of 
stars is large, however, it does not seem probable that these values can 
be seriously in error. 
TABLE II 
SPECTRAL 
TYPE 
CAMPBELL 
MOTJNT WILSON 
No. Stars 
for v' 
No. Stars 
for M 
M 
v' 
No. Stars 
v' 
0 and B ... . 
A 
141 
133 
159 
529 
72 
224 
206 
192 
549 
78 
0 .094 
0 .234 
0 .202 
0 .074 
8.99 
9.94 
13.90 
15.15 
16.55 
61 
55 
20 
/63 
\56 
27 
0".016 
0 .019 
0 .011 
0 .013 
0 .014 
0 .015 
8.23 
10.04 
10.14 
10.60 
11.53 
12.56 
F 
K/ 
M 
The omission of 5 stars of the A type would reduce the proper motion 
for Campbell's stars from 0''.094 to 0''.079. The principal feature of 
this comparison is the relatively close agreement of the Lick and Mount 
Wilson results for the B and A stars, and the large difference for those 
of other types. This difference appears to be associated directly with 
the great increase in proper motion between the A and F type 
stars in Campbell's Hst. With the aid of the relationship already 
referred to between proper motion and radial velocity deduced by 
Kapteyn for the K stars it is possible to apply corrections to Campbell's 
results to reduce to the proper motion 0''.031 of the B stars. The 
resulting values are shown under in Table III. In addition both the 
Lick and the Mount Wilson velocities have been corrected for the effect 
of stream motion by the approximate method devised by Eddington.- 
