43 



scale is continued only up to 12"'.() and for this magnitude agrees 

 with the Mt. Wilson scale. 



Now we determine the numbers .1,,,. For the bi-ightest magnitudes 

 we find then a declivity, which surpasses by far the greatest decli- 

 vity, found in Kapteyn's curve. This value, great as it is, may 

 perhaps be explained from the manner, in which the diameters have 

 been reduced to magnitudes. Excluding of these values being unde- 

 siral)le a priori and not possible on account of the small interval 

 of magnitudes, we have smoothed the numbers observed hy a con- 

 tinuons curve. Then we find from 4 determinations: 

 jr == 0".00075 ± 0".00006. 



From Shapley's research (1. c. p. 79) we derive for the mean 

 photographic magnitude of the variable cluster stars which are 

 probably ö Cepheids, ??i=15.2 and we found 5 log. :t = — 15.4, 

 so that according to our determination of the parallax their mean 

 absolute magnitude = 4.8 ^). 



From 2 variable stars with known period Shapley (1. c. p. 82) 

 found for the parallax the value: 



jr = 0".00008. 

 Messier 67. 



N.G.C. 2682;«,,o„ = 8''45'".8, ff„„„z= + 12°TL', /y=+34°, /=183o; 

 class: D 2. 



E. Fagerholm. Ueber den Sternhaufen Messier 67. Inaug. Diss. 

 Upsala, 1906. 



The catalogue contains 295 stars. The magnitudes were derived 

 from the diameters by means of Charlier's interpolation-formula, 

 after the visual magnitudes of 15 stars had been determined photo- 

 metrically. 



H. Shapley. Studies etc. III. A catalogue of 311 Stars in Messier 

 67, Contrib. Mt. Wilson Observ. W. Ill, 1916. 



For all stars the photogr, magnitudes have been determined and 

 also the photovisual ones for all stars within 12' of the centre. In 

 this way 232 colour indices were found. Shapley finds a much 

 greater number of back-ground stars than would be expected. 



Olsson's catalogue cannot be used on account of the inaccuracy 

 of the magnitudes. 



We first make use of Fagerholm's catalogue. The magnitudes that 

 are expressed in the P. D. scale, are reduced to the Harvard scale 

 by adding a correction — 0"'.2. 



1) The values of the parallax and the mean absohite mapnitii(ie yiven liere, are 

 to be preferred to the preliminary results published in the first communication. 



