14 



The results obtained are able to clear up tlie cliscrepaiicies cited 

 above from Leiden Ann. XIV. At the same time they form an in- 

 structive example of the un«afetj of extrapolation, as just at about 

 5'", which was the limit of brightness of the stars concerned in 

 roeiden Ann. XIV, tiie magnitude equation of the estimated colour 

 changes its character. 



The above considerations rest on the assumption, that stars of 

 the same spectrum do not show any systematic change of effective 

 temperature wilii apparent magnitude. As long as we have no other 

 reliable colourequivalents of these stars, this seems to be the most 

 plausible supposition, which can be used. 



