ASTRONOMY: SHARES AND SHAPLEY 
483 
DISTRIBUTION OF COLORS AMONG THE STARS OF 
N. G. C. 1647 AND M 67 
By Frederick H. Seares and Harlow Shapley 
MOUNT WILSON SOLAR OBSERVATORY. CARNEGIE INSTITUTION OF WASHINGTON 
Presented to the Academy, Auguit 4, 1915 
Recent investigations have given the colors of a considerable num- 
ber of stars in two of the moderately large and open clusters, and it is 
of interest to examine the results for peculiarities of distribution and 
frequency. Although the data are slender, several points are revealed 
with some clearness. 
N. G. C. 1647 
The data for N. G. C. 1647 consist of effective wave-lengths for 184 
stars determined by Hertzsprimg.^ Directly observed color indices^ 
are also available for about 50 of these objects, but, as the two series of 
results are in close agreement, the discussion is based upon the effective 
wave-lengths alone. The following correspondences between color 
class^ and effective wave length were established: 
Effective Wave-Length 4190 4260 4330 4400 4470 4540A 
Color Class bO aO fO gQ kO mO 
Counts within six 5 '-zones gave the results in Table I, which shows 
the number of stars of each color within each zone, and also the totals, 
the relative areas of the zones, and the densities per area of 25 tt sq. 
min. of arc. 
TABLE I 
Color and Distance — Number of Stars in N. G. C. 1647 
COLOR 
ZONE 
TOTALS 
0'-5' 
5'-10' 
10'-15' 
15'-20' 
20'-25' 
2.'5'-30' 
h 
2 
4 
5 
1 
1 
1 
14 
8 
15 
16 
4 
9 
12 
64 
/ 
12 
10 
14 
14 
7 
13 
70 
g 
0 
3 
4 
3 
4 
3 
17 
k 
0 
0 
4 
1 
7 
0 
12 
m 
1 
1 
1 
1 
1 
2 
7 
Totals 
23 
33 
44 
24 
29 
31 
184 
Relative area . . . 
1 
3 
5 
7 
9 
11 
36 
Density 
23.00 
10.99 
8.80 
3.43 
3.22 
2.81 
A comparison of the totals for the three inner zones (TVi) with those 
for the three outer {N^ suggests that the condensation may vary with 
