310 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1908. 



Already we may see now how incorrect it is to imagine all the stars 

 of the fifth magnitude to be placed at one and the same distance as 

 Struve placed them. 



According to the numbers in our figure, the distance varies from 

 1670 light years for the stars of the first box, to 11 light years for 

 those of the last. It is true that just the data for these extreme 

 boxes are the most uncertain; still, it is evident that even in these 

 mean distances there must be an enormous range. 



But to proceed, the 8G stars in our sixth box (fig. 2) are at an 

 average distance of 248 light years. Are we compelled to stop here 

 and to assume that the real distance of all the individual 86 stars is 



45 



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 MIIGU 



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152 



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 79 



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Fig. 2. 



-Magnitude-motion Boxes. 



248 light years? If it were so we would surely still have gained a 

 considerable advantage over Struve. For, owing to want of other 

 data, he saw himself compelled to treat all the stars of the fifth 

 magnitude, that is, the whole of the 28 groups in our boxes, as if they 

 were all at the mean distance of the whole. 



But yet there would remain in our solution a defect of the same 

 kind, and it would be impossible to say in how far the results 

 definitively to be obtained w^ould be influenced. 



Happily there is an escape. For our last classification, the classifi- 

 cation in the distance boxes, it is of no particular advantage that 

 every individual star gets in its proper distance box. It will be suf- 

 ficient to know how many stars will finally be found in each distance 



