Nipher — On Temperatures in Gaseous Nebulae. 281 



This is Hitter's equation more recently announced by Dr. 

 See. 



In the early history of a nebula, the temperature undoubt- 

 edly approaches very closely to uniformity throughout the 

 mass. And in the case of the sun, which represents the final 

 stage of a nebula, it seems possible that the same conditions 

 may hold through the greater part of its mass. 



In general the temperature throughout a nebula is to be 

 given in terms of the co-ordinates of the point in space where 

 the temperature is to be determined, and the ratio of contrac- 

 tion from any given initial condition. 



If the temperature throughout the mass remains constant, 

 Ritter's equation (25), holds during contraction. If on ac- 

 count of unequal permeability to heat the temperature should 

 become unequal, the law of temperature change as a function 

 of ratio of contraction, becomes more complex. If at any 

 time the temperature throughout the mass varies inversely as 

 the n*^ power of the distance from the center, the ratio of 

 temperature change at any contracting surface is given by 

 (24). It is evident that n cannot be less than zero. This 

 is fixed by physical considerations. If it were less than zero, 

 the temperature would increase from the center outwards. 



It is not probable that these equations could represent the 

 general behavior of the nebula throughout its mass, if the 

 temperature departed materially from constancy, as it prob- 

 ably does in the latter stages of condensation. This discus- 

 sion at least shows that such conditions of temperature, 

 produce effects that should not be ignored. 



Another hypothesis in regard to the temperature within 

 and around the sun may be outlined, although the study of 

 the resulting consequences is as yet in an unfinished state. 



Let it be assumed that the temperature varies along any 

 solar radius in accordance with the equation 



log T=\ogB{R'-R). (26) 



In this equation, R is the radius of a spherical surface at 

 which the temperature is unity. The temperature at the 

 center is from {2Q) 



T, = B^'. (27) 



