I. The Parallaxes of Globular Cliisters. 



Most celestial objects, which, as regards their distribution in the sky, prove 

 to be dependent on the galactic plane, seem to be uniformly distributed in galactic 

 longitudes. This is the case with the eclipsing variables, c and ac stars, stars of 

 Type IV and S-Cephei variables 84 . The Helium-stars and the stars belonging to class 

 Oa — Oe , on the other hand, are concentrated tovvards one side of the ring of the 

 Milky Way 37,84 (X 248° and 305° resp.) and, again, for the planetary nebulse we also 

 find a concentration corresponding to the Oa — Oc stars. A still more strongly pro- 

 nounced dependence on the galactic longitude is shown by the globular dusters and 

 the spiral nebulse. The distribution in the sky of these objects has recently been 

 studied by, among others, Bailey 5,9 , Bohlin 24 , Charlier 37,39 , Fath 66 , Hardcastle 74 , 

 Hinks 89,90 , Hertzsprung 84 , Melotte 128 and Perrine 146 . Concerning globular dusters 

 ifc has come forth as the main result of those researches, that they occur exclusively 

 in a hemisphere, whose pole has the galactic coordinates X + 296°, p — 9°, and that 

 they are particularly strongly concentrated in the great står cloud in Sagittarius 39 . 



The spiral nebulse, on the other hand, were formerly assumed to be symmetri- 

 cally distributed round the galactic plane and concentrated at its poles, but other- 

 wise uniformly distributed in galactic longitude. While the globular dusters seem 

 to form a system, the members of which may be almost all known 11 , and whose 

 number, it seems, is not above 80, the spiral nebulse are certainly to be estimated 

 to millions 53 , and to formulate a general law, rendering their distribution in the sky, 

 will probably not be possible out of the scanty material, that, as yet, is at our 

 disposal for researches into their distribution. Nevertheless, it is evident from 

 HardcastleVHinkV 4 and from Fath's 66 researches, that in the law expressing their 

 distribution galactic longitude must also form part as an important parameter. 

 Max Wolf's studies with the aid of stellar photography of small nebulse also show, 

 that the spiral nebulse in several regions gather in cluster-formations (at the pole of 

 the Milky Way 233 , in Perseus 245 , in Cetus). We can certainly expect to find a very 

 complicated structure in the doubtlessly gigantic universal system, which is formed 

 by the spiral nebulse. 



The enigmatic distribution of globular dusters and spiral nebulse has since the 

 days of Herschel tempted many scientists to occupy themselves with more or less 

 hypothetic deliberations as to the distribution in space of these objects. Already 



