Nipher — The Law of Contraction of Gaseous Nebulae. 149 



According to these equations the density and pressure are 

 infinite at the center of the mass. This is, however, the value 

 at a single point. At any small finite distance from the cen- 

 ter, both are finite. Of course the gaseous matter at and 

 immediately around the center is, or may be, also liquid and 

 solid. There may be no dividing surface between solid, liquid 

 and gas, by reason of the enormous pressures in the central 

 part of the nebula. 



By inspection of equations (19) (20) and (21), it will be 

 observed that, entirely irrespective of the value of n. 



(23) 



(24) 



(25) 



irhere 



By eq . (17) this equation may also be written 



/ ZTTK \J- / \ 2. 



^ = ((-4ir3S)s)"((2-»)era)- 



The product CTB is constant at the surface of any 

 constant mass forming the core of a gaskugel, as eq. (17) 

 shows, whatever maybe the gas of which it may be composed, 

 and whatever may be the radius of the contracting core. 



These equations should be compared with (3), (6) and (7). 

 These equations involve the relation between P, 8 and T, at 

 the surface of any fixed mass forming the core of a gravi- 



