( 128 ) 



Pole will increase and tiiat towards the South galactic Pole will 

 diminish or disappear. From the circumstance that the nearest 

 galactic region in the direction of XIX h. (towards C) has a noi'thern 

 galactic latitude it moreover follows that the maximum of nebulae of 

 the northern gal. hemisphere lies within more than 90 degs. of the 

 galactic equator in a great circle passing through C and M, whereas 

 in the southern galactic hemisphere the maximuni of nebulae is 

 situated on the Cygnus side of the Pole (towards in^). 



This theoretical consideration has been tested by observation in 

 the followhig way. On the nuxps for the distribution of the nebulae 

 by Stratonoff {Puhl. Tachkent 2, [)1. 18 and 19) we have estimated 

 in a zone ir)" wide in the direction of the galactic meridian of 

 45°, which ciosses the C!ygnus region the densities in areas from 

 10 to 10 degrees galactic latitude. Tiie result is given in table VI. 

 (For tables I — V see the paper "-On the apparent distrlhaüon of 

 nebulae"). 



The much smaller densities of the southern galactic hemisj>here 

 could be expected owing to the greater incompleteness of tiie ol)ser- 

 vations; for the rest the displacements of the maxima from the Poles 

 are in the same sense as they should be according to tiieory. In 

 how far the hypotheses made are thus supported caimot be decided 

 because of the incompleteness of tlie data, at any rate they are not 

 at variance with the results of the observations. 



If, with the now available data, particulars are to be detected 

 concei'uing the true distribution of the nebulae, we shall have to 

 look for traces of them in those regions where the galactic and 

 the extra-galactic regions meet. In a mean galactic latitude we shall 

 have to search for the great irregularities in the ajjparent distribution 

 of the nebulae and compare the places where they oc«'ur with the 

 places where the irregularities in the distribution of the stars are 

 found, especially the irregularities in brightness and in width of the 

 diffused light of the Milky Way. 



To this end the following tables have been constructed (VII, VIII, IX). 



Over Stratonoff's maps of the distribution of the bright (n. bril- 

 lantes) and faint (u. faibles) nebulae, a galactic system of coordinates 

 was laid. For each area of 15° in gal. longitude and 10° in gal. 

 latitude we have then estimated as carefully as possible the density 

 of bright and faint nebulae. These values were combined with due 

 regard to the unequal surfaces of the areas in order to obtain the 

 mean densities for zones of 15"" gal. longitude between O"" and 50° 

 gal. latitude on either side of the galactic equator (table \ll). For 

 the galactic zone proper, between +10'' and — 10" gal. latitude, 



