152 
ASTRONOMY: W. S. ADAMS 
hanced lines in the early F stars are normally so prominent that it is 
not surprising that the method begins to break down at this point. 
To illustrate the use of the formulae and curves we may select as il- 
lustrations a few stars of different spectral types and magnitudes. These 
are collected in Table 11. The classification is from Mount Wilson 
determinations. 
TABLE II 
STAR 
6 
< 
TYPE 
A 
M 
PARALLAX 
(a) 
(b) 
(c) 
(a) 
(b) 
(0 
Mean 
Comp. 
Obi. 
Pi 10^96... . 
7.6 
F5 
-0.7 
+0.7 
+3.0 
+6.5 
4.7 
5.8 
5.7 
+0'f04 
+0!04 
GO 
-0.5 
+0.5 
+3.0 
+5.6 
4.3 
5.8 
5.2 
Lai. 38287.. 
7.2 
G5 
-1.8 
+ 1.5 
+3.5 
+7.4 
+6.3 
+6.2 
7.3 
+0.10 
+0.09 
a Arietis. . . 
2.2 
KG 
+2.5 
-2.4 
+0.2 
+ 1.0 
1.3 
+0.2 
0.8 
+0.05 
+0.09 
a Tauri. . . . 
1.1 
K5 
+3.0 
-2.0 
+0.5 
-0.4 
+ 1.9 
+0.5 
0.7 
+0.08 
+0.07 
612 Cygni. . 
6.3 
K8 
-1.8 
+5.8 
+7.7 
+8.2 
9.3 
8.9 
8.8 
+0.32 
+0.31 
Groom. 34.. 
8.2 
Ma 
-2.2 
+6.8 
+9.2 
+ 10.2 
10.5 
10.4 
10.4 
+0.28 
+0.28 
The parallaxes are computed from the absolute magnitudes by the 
formula, to which reference has already been made, 
5 log TT = M — m — 5. 
The results are given in the next to the last column of the table, and 
the measured parallaxes in the final column. 
INVESTIGATIONS IN STELLAR SPECTROSCOPY. III. APPLICA- 
TION OF A SPECTROSCOPIC METHOD OF DETER- 
MINING STELLAR DISTANCES TO STARS 
OF MEASURED PARALLAX 
By Walter S. Adams 
MOUNT WILSON SOLAR OBSERVATORY. CARNEGIE INSTITUTION OF WASHINGTON 
Received by the Academy, February 8, 1916 
A definite test of the value of this method of deriving stellar paral- 
laxes can be made only through a comparison with all available data on 
measured parallaxes. Since the evidence depends directly on individual 
values it is necessary for this purpose to present tables of a somewhat 
extended character. 
It is evident that in the case of the stars whose absolute magnitudes, 
as computed from the measured parallaxes have been used in the deriva- 
tion of the relationship between fine intensity and absolute magnitude, 
the mean values of the magnitude will necessarily be identical with those 
derived from the formulae. The agreement of the measured and the 
