CHAPTERS ON THE STARS. 425 



to our readers. I have, therefore, derived their general mean results for 

 different parts of the sky with reference to the Milky Way and for stars 

 of the various orders of magnitude. The following table shows the con- 

 clusions: 



In the first column we have the designation of the zone or region 

 of the sky, as already given. 



In the second and third columns we have the mean ratio of increase 

 for whole magnitudes as derived from the Durchmusterung and the 

 southern Durchmusterung, respectively. It will be recalled that region 

 I., around the north galactic pole, is entirely wanting in the S. D., while 

 the adjoining regions, II. and III., are only partially found, and that, in 

 like manner, the D. M. includes none of region IX. around the south 

 galactic pole, and but little of the adjoining region. 



It will be seen that there is a very remarkable systematic difference 

 between the two lists, the ratio of the number of faint to that of bright 

 stars being much greater in the S. D. This difference is shown in the 

 fourth column. I have assumed that the two systems are equally good, 

 and there diminished all the ratios of the S. D. by 0.25, and increased 

 those of the D. M. by the same amount. The mean of the two corrected 

 results was then taken, giving the principal weight to the one or the 

 other, according to the number of stars on which they depend. 



It will be seen that the increase of the ratio from either galactic pole 

 to the Milky Way itself is as well marked as in the case of the richness 

 of the respective regions in stars. We may condense the results in this 

 way: 



In the galactic zone, ratio = 3.85 



In zones IV. and VI., " = 3.53 



In polar zones I., II., VIII. and IX., " = 3.28 



It will be recalled that zone V. is a central belt 20° broad, including 

 the Milky Way in its limits. But the latter, as seen by the eye, espe- 

 cially its brightest portions, does not fill this zone. These portions, as 

 we know, comprise the irregular collection of cloud-like masses de- 

 scribed in the last chapter. Seeliger has investigated the ratio within 



