ASTRONOMY: H. SHAPLEY 
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east side of the Milky Way (in the part of the sky under consideration) 
there are scarcely any bright B-type stars; on the west there are hun- 
dreds of them. The remarkable inequality gives rise to what was called, 
in an earlier paper, the 'Secondary Galaxy.' This sub-ordinate Milky 
! I I ! I 
Fig. 2. Distribution of bright B stars, from the Henry Draper Catalogue. Crosses refer 
to sub- types BO, Bl, and B2 (and undefined B's); the dots refer to sub- types B3 and B5. 
The curves are described in the text. The large circle shows the position of Sirius; the 
trapezoid indicates the constellation Orion. The direction of the center of the local cluster 
falls near the lower right-hand corner of the diagram. 
Way, though well defined by star analyses throughout its complete cir- 
cuit of the sky, to the naked eye is most clearly seen in the region 
mapped in figure 1, where it stands out some 10 to 20 degrees along 
the west side of the Milky Way from Perseus southward through Taurus, 
Orion, and Cards Major to Puppis and Carina. Not only the very 
