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POPULAR SCIENCE MONTHLY 



gone into numerous smaller stars. Accepting this view, it would fol- 

 low that the material in question was a sheet so thin that the thickness 

 of the space filled by the cluster was an appreciable fraction of that oc- 



Fii;. 1. Photograph showing Structure of the Milky Way, by' Barnard. 



cupied by the stars. In other words, one-fifth of the stars of the region 

 would be contained in a thin sheet. This result seems too improbable 

 to be accepted. 



The other and more likely conclusion is that the number of very 



