Nipher — Primitive Conditions in the Solar Nebula. 119 



An inspection of this equation shows that for any fixed 

 value of T, there will be a definite value of R which will 

 make the radius R of the isothermal T a maximum. 



The condition for this maximum is 



The condition thus determined i? 



dR ' / T 



^o = 



-,n— i 



2(7i — l) (2 — ft) 2 _W 



4 — 3ft 0.9975(4 — 3n)>i2C7 T ' 



(59) 



According to this equation, the higher the temperature of 

 the isothermal the smaller must be the radius of a contracting 

 nebula when the radius of the isothermal has reached its 

 maximum. This shows that the outer isothermals are con- 

 tracting, while the inner ones are enlarging. The maximum 

 radius R of any isothermal is found by substituting the value 

 i? of (59) in (58). The maximum R is 



R = 



1 + 



2(ft— 1) 

 4 — 3?i 



2— « 



■in 



(60) 



In like manner this value i? in (57) gives for the value of 

 x when R for any isothermal is a maximum 



(-)= X 



\Ro/ R=ma 



m- 

 max. 



4— 3ft 



ft 



In 



(61) 



In the former paper it was shown that for oxygen, hydro- 

 gen, nitrogen, and air, n= 1.101. Hence 



x = 0.901. 



