12 BOHLIN, ON THE GALACTIC SYSTEM WITH REGARD TO ITS STRUCTURE. 
1802) HERsSCHEL delivers himself from this somewhat starry idea, and expresses the 
opinion that the Milky Way is made up of stars, which are otherwise scattered than 
the stars in our vicinity. And in the memoir of 1811, it is expressely pointed out 
that the assumption of uniform distribution of the stars is to be given up for the 
Milky Way and for the star groups. 
After HERSCHEL, the most complete inquiry of the distribution of stars is due 
to SEELIGER, by his recent researches, based on the » Durchmusterung» of stars by ÅRGE- 
LANDER and SCHÖNFELD (magnitudes 1—9), the CELORIA stars, comprising inclusive 
the 11.5 magnitude, and finally the Herschelian gauges as completed by HoLDEN 
u. The researches of SEELIGER can be summed up as follows. The ÅRGELANDER 
SCHÖNFELD stars are divided into seven classes, namely: 
Class Magnitudes 
1 1.0 to 6.5 
Z 6.6 >» 7.0 
SR US 
ANT ESS 
D STL SAST 
60-865 > 9.0 
ZH 001 3 195 
For every class, the number of stars in every quadrangle of a reticule, disposed after 
equal differences of right ascension and declination, is summed up. Hence it is easy 
to evaluate the density of stars per square degree in the different quadrangles of the 
sphere. These numbers, arranged in a table with double entrance, constitute the ma- 
terial, suitable for the inquiry. S. divides, furthermore, the celestial sphere into zones, 
parallel to the Milky Way, each 20” in breadth. Thus one gets nine zones, of which 
the ninth, comprising the south pole, is still left out of account. The fifth zone com- 
prises the Milky Way. There is no difficulty to confine, within lines drawn in the 
tables, the numbers corresponding to every Galactic zone. The concentration of 
stars of all seven classes to the plane of the Milky Way is thus plainly shown. Tf 
the density of the fifth zone is taken for unity, the average density for the star 
classes 1—7 is got up as follows: 
Zone = Stars density 
I 0.35 
2 0.36 
3 0.45 
4 0.68 
kar 
6 Or 
7 0.47 
8 0.41 
9 
