150 Trans. Acad. Sci. of St. Louis. 



tating gaskugel, the pressure being due to the alleged at- 

 traction of this core for the superposed layers. Equations 

 (3), (6) and (7), involve no such conditions. 



If we assume that the mass M has initially a radius P^, 

 and that it contracts to a radius i?, so that P^ = pPy thea 

 the two equations for P will be 



^' ~~ Sttw P,^ 



4 — 3n M'^h 



P = 



87rn P^ 



Hence 



In Ritter's well-known paper of 1878* he established the 

 relations involved in the last three equations, by an ingenious 

 train of reasoning. He assumes a gravitating weltkugel to 



so contract, that any and every linear distance has become — 



of its original value. Then the volume of unit mass at any 

 point, in terms of the initial volume, is 



V = o ' 



By reason of this contraction, the gravitational pull on eack 



*■ Annalen der Phvsik uod der Cheni'e. Bd. V, S. 549-50. 



