KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 60. N:0 8- 



61 



a means to derive the distance to the Andromeda spiral, provided the true dimensions 

 are the same in both cases. From variable stars Shapley has found for the small 

 Magellanic cloud z = 0",oooo52, which might be the hitherto most certainly determined 

 parallax-value for this object. As N. G. C. 224 has a diameter of 120' and the dia- 

 meter of the cloud is about 300' we obtain: 



"Andr. = 0",000024. 



For N. G. C. 371, connected with the small Magellanic cloud, follows, according 

 to the principles of Shapley, z = 0",oooo33, which gives: 



"Andr. = 0" ; 00001 3. 



O ur discussion consequently has given the following result regarding the 

 parallaxes of the spiral nebuke: 



N:r 



Method 



l Andr. 



From direct parallax-measures 



According to Jeans' theory 



From står counts 



From Wolf's measurements of the -caves» 

 From spectral and photometrical researclies 



From proper motions and radial velocities . 



From the rotational motions 



From the nov;c in spiral nebuhc 

 From the small Magellanic cloud 



: 0",005 

 : 0,0007 

 ; 0,000420 



; 0,000005 



small 



J0,000284 1 



10,000163 / 



(0,000358 1 



: 1(0,000221)/ 



; 0,00000024 



; 0,0000009 



0",000080 

 0,000100 



0,000005 

 0,000018 



Diameter in light-years 

 for N. G. C. 224 



> 23 

 = 1400 



> 270 



> 1140 



> 510 



> 290 



=23000 

 = 6300 



The values in the table calculated for ~ m according to the 4 fch , 8 th and 9 th 

 methods have been obtained by assuming, in conformity to Tables XIV and XV, that 

 the mean parallax of the known spiral nebulse is 1 /n of that of the Andromeda nebula. 



The first value only indicates that direct parallax-measures cannot be employed 

 for determing the distances of spirals. The third value is an upper limit. To the 

 fourth and following two methods no great importance is here to be attached owing 

 to the uncertainty and the small number of the observations. The greatest importance 

 must be attached to the parallax-value obtained from the novce as no less than 11 novse 

 have been registered in the Andromeda nebula. I will here add that it is at the 

 calculating of z not necessary to accept the galaxy-theory concerning the Andromeda- 

 nebula. Even if ShapleyV 01 wiew is adopted that the novse in spirals may be 

 considered as the engulfing of a står by rapidly moving nebulosity, the appearance 

 of novse in spirals might nevertheless be employed for an estimation of the mean 



