492 
ASTRONOMY: C. D. PERRINE 
size of proper motion. The results for the different spectral classes are 
given in table 1 where the numbers of stars in the groups are in 
parentheses. 
TABLE 1 
Prolateness from Radial Velocities 
P2/P1 
SPECTRAL CLASS 
Campbell's l. o catalogs 
ADAMS' MT. WILSON 
CATALOG 
2.9 and brighter 
3.0 and fainter 
Small n 
Large /x 
Small ix 
Large ^^ 
Small fx 
Large )U 
B 
(30) 1.81 
(113) 0.96 
( 81) 0.82 
A 
(127) 1.18 
(31) 1.79 
(110) 1.23 
(9) 1.88 
F 
(38) 1.17 
(126) 1.63 
(18) 1.33 
(11) 2.00 
G 
(81) 1.31 
(41) 1.54 
(55) 1.64 
(29) 2.88 
K 
(226) 1.09 
(124) 1.42 
M 
(52) 1.19 
(13) 1.96 
K,M 
(20) 1.23 
(18) 0.87 
(84) 1.17 
(31) 1.19 
A, F, G 
(18) 4.56 
(25) 1.50 
With the exception of the K and M stars of Adams' catalog and those 
of 2.9 and brighter of the same classes in Campbell's catalogs, a con- 
sistently smaller prolateness is shown for the small than for the large 
proper motions. These exceptions may be only coincidences, but they 
require further investigation. 
The underlying idea in this investigation was that the nearer stars 
(those of large /x and also the very bright stars) might be subject to 
different preferential motions from the more distant stars. This was 
indicated by anomalies in the position of the apex of solar motion yielded 
by 110 of the stars of magnitude 2.9 and brighter, and in the positions 
yielded by the different sizes of proper motion. It is to be noted that 
the 30 bright B stars show a large prolateness and are quite consistent 
for so small a group — half of the velocities in the regions of the vertices 
of the ellipsoid are larger than any in the regions at right angles to the 
axis. The large velocities are found in the region of both vertices. The 
indications that the very distant stars are not subject to preference of 
motion for the ellipsoidal axis furnishes a satisfactory explanation of the 
peculiar behavior of the class B stars. 
A dissymmetry has been observed in the velocities of the A, F, and G 
stars of small fx north and south of the ellipsoidal axis which produces 
the effect of a considerable prolateness. It is in the nature of smaller 
average radial velocities for the northern stars than for other parts of 
the sky. If determinations of prolateness are confined to northern stars 
