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 B^ which will 

 make the radius H of the isothermal T a maximum. 



The condition for this maximum is 



dli\ 



rlKJl 



==(9. 



o/r 



The condition thus determined ic 



^0 = 



-ytl—l 



2(n — l) 

 i — 3n 



(2 — ny 



JcM. 



P , 



0.dd75(4: — Sn)n2CT 



(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 isothcrmals are con- 

 tracting, while the inner ones are enlaro;ino;. The maximum 

 radius M of any isothermal is found by substituting the value 

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



i2 = k 



1 + 



2{n—l) 

 4 — 3m 



■2 — n 

 '2n 



(60) 



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

 X when li for any isothermal is a maximum 



(^^o).^^. 



— x^. 



0/ Ji=max. 



4— 3/i 

 2—n 



1-n 

 In 



(61) 



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

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



x = 0.901, 



