Vol. 8, 1922 
ASTRONOMY: G. STROMBERG 
141 
loci of the roots of j{z) , and also where we consider not merely the first but 
the derivative of J{z). The writer hopes to continue the study of 
these problems. 
1 See paper by the writer, Trans. Amer. Math. Soc, 22, 1921 (101-116). 
2 See a forthcoming paper by the writer in the Trans. Amer. Math. Soc; a similar 
result holds for any number of equal circles d which have collinear centers. 
3 This problem is set forth explicitly in the paper referred to in the preceding footnote. 
ON THE DISTRIBUTION OF THE VELOCITIES OF STARS OF 
LATE TYPES OF SPECTRUM 
By GusTAif Stromberg 
Mount Wii^son Observatory, Carnejgie Institution of Washington 
Read before the Academy April 25, 1922 
The recent determination of spectroscopic paralaxes or stars of the 
later types of spectrum made by Adams and his collaborators^ at the 
Mt. Wilson Observatory has made it possible to compute the absolute 
motions in space of about 1300 stars of spectral types A7 to M for which the 
proper motions and radial velocities are known. The spectroscopic paral- 
laxes for which the errors are proportional to the parallaxes themselves are 
in general better adapted for this purpose than the trigonometric paral- 
laxes since the accuracy of the smaller parallaxes is considerably greater. 
The three velocity-components of these stars have been computed with 
reference to the galactic system of coordinates, the pole of galaxy being 
assumed to have the position A = 190.6°; D = -f- 27.2°. This system 
of coordinates is very convenient in the study of the systematic motions of 
the stars since these motions are mainly in the galactic plane. 
Solar Motion. — The solar motion can be obtained directly by forming the 
algebraic mean of the velocity-components which are measured with ref- 
erence to the sun. By taking the opposite vector we find the sun's velocity 
relative to the group of stars employed. The following values for the 
sun's velocity have been derived in this way. 
SPECIAIv 
V 
TYPE 
M 
NO. 
Ao 
Do 
KM. 
A6toF9 
<3 
153 
269° 
H-27° 
21.2 
>3 
133 
274 
35 
23.4 
GO to G9 
<3 
224 
266 
32 
19.9 
>3 
154 
279 
23 
40.2 
K0toK9 
<4 
325 
282 
43 
18.3 
>4 
112 
286 
31 
33.1 
M 
<4 
98 
271 
44 
16.2 
A6 to M 
. . . Giants 
800 
273 
37 
18.8 
A6 to M 
415 
281 
29 
31.7 
