This memoir contains, in the main, the notes distributed to tVie auditors of ray 

 lectures in the autumn-term 1911. It has in view to give a contribution to the 

 solution of the problems, which the Milky Way offers to the astronomers. In the 

 present memoir I consider the question of the number of stars in different parts 

 of the Milky Way as well as the distribution of the luminosities of these stars. In 

 the second memoir these problems are considered from other points of view. In 

 a third memoir I intend to treat the question of the motions of the stars. 



