Nip]ier — The Law of Contraction of Gaseous Nebulae. 159 



4 

 If n were o the average density would be at the center, 

 o 



The average pressure within radius B may be found by 



substituting P from eq. (10) in the equation 



I- 



Pa = ^^ =3|^P. (37) 



47r I RMR 



It is to be observed that if n were as hirge as 1.2 the aver- 

 age pressure within the mass ilf would be infinite. Making 

 n = 1.1 the average pressure is found to be 5.4 P. 



By (10) the average pressure is distant from the center of 

 mass 



^» = (s '^'P ^ = '•'''' ^- («')• 



If n = 1.2 the average pressure would be at the center. 

 It is therefore clear that n must be less than 1.2 in order that 

 the distribution may be physically possible. The value with 

 ?i = 1.1 is given above. It locates the gas of average pres- 

 sure almost exactly midway between the center and the spher- 

 ical surface of radius R. 



The average temperature, deduced in the same way from 

 (12), is 



T^^l^ T=l.OST. (39) 



The distance from the center to the surface having this tem- 

 perature is 



2—71 



BJ^ ^-^'' f^'li = 0.707R. (40) 



