stellar dusters 



23 



Even here we find a concentration against the Milky Way, there being only 

 18 globular clusters in the 24 polar squares against 58 in the 24 squares along the 

 galactic equator. Differently from the ordinary clusters we find, however, that the 

 globular clusters are by no means approximately in a uniform manner distributed 

 on the galactic squares, more than 50 °/o being found in the four squares (rCj^, 

 GC,2, GD^^ and GD^^. 



For graphically illustrating the distribution of the globular clusters it is con- 

 venient to place the squares GC-^^ and GD^^ in the midst of the diagram and not 

 at the border as in fig. 1 of plate I. Such an arrangement is performed in the 

 figure 1 of plate IV, where the ascending node of the Milky Way on the celestial 

 equator is placed in the midst of the diagram. 



The concentration in the apparent distribution of the globular clusters about 

 I = SSO**, remarked by Hinks, is obvious. We find from fig. 1 on plate I that 

 the squares GC^^, CrC^,,, GD^^, GD^^ correspond to the constellations Scorpius, 

 Ophiuchus, Corona Australis and Sagittarius, which thus are the home of the glo- 

 bular clusters. We come back in § 20 to an interesting feature in the remarkable 

 distribution of these objects. 



12. For getting a more or less approximate representation of the relative 

 distances of the globular clusters we may take recourse to the same three attributes 

 that were mentioned regarding ordinary clusters namely 1) the apparent diameter, 

 2) the apparent magnitude of the stars in the cluster, 3) the spectral type or color- 

 index of the stars *. Here even others attributes may be taken into consideration, 

 namely 4) the integrated magnitude of the cluster and 5) the variables in the glo- 

 bular clusters. Moreover even 6) the number of stars down to a certain magnitude 

 learns us something regarding the relative distances of the clusters. 



Of these attributes only 1) is, for the present, known for all globular clusters, 

 but we find from the table 2 below that — thanks to the indefatigable endeavours 

 of Mr Bailey — even 2) and 6) are, approximately, known for the greater part of 

 them. Even regarding 5) Bailey has given us much information though not yet 

 on a uniform scale for all globular clusters. Regarding 3) highly interesting results 

 are published by Shapley from the Wilson observatory in the moment when these 

 lines are written. There are some reflexions on these results at the end of this 

 memoir. 



I will here, as regarding the ordinary clusters, only make use of the method 

 1) for deducing the relative distances of the globular clusters, but I insert some 

 remarks on methods 2) and 4). 



* The spectral type and color-index of a star do not change with varying distance, but may, 

 nevertheless be used for distance-estimates in combination with 2). 



