52 



KNUT LUNDMARK, GLOBULAR CLUSTERS AND SPIRAL NEBULiE. 



in the Orion nebulse) are formations of a kind that occurs also in the spiral nebula?, 

 and that in both cases the absolute dimensions are on an average the same. By 

 measuring the breadth of the »Längshöhlen» and »Querhöhlen» (length- and cross- 

 caves, or rifts) he derives relative parallaxes for 8 of the large spiral nebulae. 

 Then, in order to obtain the true distances, he starts from the distance estimated 

 by Campbell to the Helium stars related to the Great Orion nebula (~ = 0",oo8), and 

 concludes, as the breadth of the »Längshöhlen» in the Orion regions is 72' and the 

 breadth of the »Querhöhlen» 20', that the Andromeda nebula, for which the same 

 values have been estimated to 70" and 18" respectively, is at a distance of 10000 

 parsec. By assuming Nova Persei 1901 to be situated in the galactic drift in Per- 

 seus, and estimating the average breadth of the »Längshöhlen» to 120' and of 

 the »Querhöhlen» to 30', and by supposing that the parallax for Nova Persei can 

 be fixed to 0",oi, he obtains a new determination of the parallaxes of the nearest 

 spiral nebulae that is in close accordance with the first determination. Below Wolf's 

 results (re-calculated) are summed up: 



Table XII. 



Object 



^Oricm 



= 0",0071 



'•Nov. Pers. 



= 0",010 



Mean 



From the 



From the 



From the 



From the 





length-caves 



cross-caves 



length-caves 



cross-eaves 





N. G. C. 224 



0",000105 



0",000099 



0",00009C 



0",000099 



0",000100 



598 



38 



33 



35 



33 



35 



3031 



19 



19 



18 



19 



19 



5457 



12 



11 



11 



11 



11 



5194 



11 



8 



10 



7 



9 



4565 



S 



- 



7 



- 



7 



6946 



8 



5 



7 



5 



C 



2903 



0",000006 



0",000005 



0",000005 



0",()00005 



0",000005 



Concerning the parallax-value employed by Wolf for the Orion nebula, it 

 seems to have been confirmed by more recent determinations. Thus Kapteyn finds, 

 for the Helium stars connected with the Orion nebula, a mean parallax amounting 

 to 0",oo54, and Bergstrand has lately 20 determined the mean parallax for a group 

 of 15 bright Helium stars in and near the nebula to 0'',oos. W. H. Pickering 15 "' 

 finds a considerably cliverging value, 7c = 0",ooo5. An adoption of this parallax would 

 give a much greater distance for the spiral nebula3 than that obtained by Wolf. 

 However, in view of the uncertainty of the data employed by Pickering, no reasons 

 seem to exist for giving up the value resulting from Campbell's, Kapteyn's and 

 Bergstrand's determinations, which are in good mutual concordance. The hypo- 

 thesis of the spiral form of the Milky Way, assumed among others by Wolf, is 

 of course rather uncertain, and much speaks in favour of the supposition that the står 



